Topic catalogues

Topic catalogues list all of our reports published within each topic area / category with abstract and price. Please select a category to download the catalogue.

Wastewater Treatment & Sewerage

UKWIR maintains and is constantly adding to, an extensive library of reports which are deliverables from our research programme. Reports Catalogues are created to illustrate the reports that have been produced in each of UKWIR's research topic areas. These reports are freely available to UKWIR subscribers and they may be purchased from the UKWIR website by non-subscribers


Wastewater Treatment & Sewerage

Extending the Capability of SAGIS by Developing a Climate Change Sensitivity Analysis Tool 

Ref: 22/WW/02/16            Price: £600
ISBN: 978-1-84057-951-2

This project has delivered a spreadsheet tool that extends the capability of the SAGIS-SIMCAT system by enabling modellers to directly apply climate change related modifications to SIMCAT dat files, to process outputs and to present useful and intuitive visualisations of complex data. The tool enables water companies and regulators to explicitly include climate change considerations in SAGIS-SIMCAT catchment and asset management planning applications for PR24, thereby supporting the requirements of the Climate Change Act 2008 and the Water Industry Strategic Environmental Requirements (WISER) document. Through the automation and streamlining of data management processes, the tool reduces the time and effort associated with scenario modelling and provides more effective modelling and planning procedures that take climate change into account in water quality planning. The project has served as a multi-stakeholder forum that has facilitated the dissemination, discussion and exchange of SAGIS-SIMCAT knowledge and ideas.

There may be a significant reduction in the price of this report if you have already bought a copy of the previous SAGIS report.  If you buy this latest report, you also receive all previous SAGIS reports as attachments. Please contact the UKWIR office for assistance.

How can conventional wastewater treatment processes cope with greater volumes of weaker sewage 

Ref: 22/WW/06/11            Price: £10
ISBN: 978-1-84057-943-7

The water industry is under pressure to reduce spills from Combined Sewer Overflows (CSO), but without actions to limit infiltration and separate surface water, the consequence of this allied to climate change will be larger volumes of more dilute sewage arriving at Wastewater Treatment Works (WwTW), possibly for protracted periods. 

Hence this project takes a wider view on dealing with the dynamic nature of volumes and strengths of the sewage that the water industry is likely to need to treat. The output of this project includes realistic operational design options for existing WwTW’s processes and considers a selection of potential alternatives for WwTW dealing with intermittent higher flows of weaker sewage.

PFAS and wastewater - prevalence, reduction options and costs. 

Ref: 22/WW/14/2            Price: £10
ISBN: 978-1-84057-929-1

Per- and Polyfluoroalkyl substances (PFAS) are of emerging concern both due to their potential toxicity to humans and their persistence in the environment. This literature review was required to give the water industry a better understanding of which PFAS will be of most concern (there are 4,700 potential PFAS to consider) on the basis of production, use, and toxicity. The work also looked to anticipate possible regulatory scenarios; and finally by understanding the potential impacts and obligations on the water industry, to make recommendations to inform our responses to these pressures (both financial and regulatory).

Pharmaceutical reduction at WWTW – cost and effectiveness 

Ref: 20/WW/17/18            Price: £10
ISBN: 978-1-84057-901-7

The Urban Wastewater Treatment Directive is currently under review in 2020, with discussions being held as to whether advanced treatment for substances such as pharmaceuticals should be mandated to achieve a minimum reduction across wastewater treatment works, as is undertaken within Switzerland. This project looked at the implementation of pharmaceutical removal in Switzerland and its implications for the UK in terms of cost and effectiveness. Conclusions were drawn and recommendations made for the Water Industry and policy makers regarding pharmaceutical removal from effluent at wastewater treatment works. This knowledge will enable UKWIR and its members to inform, engage with and influence policy decision makers to ensure that any changes to the UWWTD are proportionate to the environmental benefit they will deliver.

Ecological impact of other (non soluble reactive) phosphorus fractions 

Ref: 20/WW/20/9            Price: £10
ISBN: 978-1-84057-900-0

Phosphorus is an essential element for all life and is widely recognised as a key factor influencing the status of river and lake ecosystems. Much past research and monitoring work in these ecosystems has focused on an individual fraction of the total phosphorus pool, operationally termed soluble reactive phosphorus. However, an extremely wide range of non-soluble reactive forms of phosphorus may exist in fresh waters.

The objectives of this project were to -

  • provide an independent assessment of the state of research knowledge regarding non-soluble reactive forms of phosphorus in rivers and lakes;
  • identify key priorities for future research and monitoring work in this area;
  • and consider the potential for development of a typology system to describe the ecological impacts of non-soluble reactive forms of phosphorus in rivers and lakes across the United Kingdom.

Wastewater Treatment Works Flow to Full Treatment - Monitoring and Compliance Assessment Method Development 

Ref: 18/WW/21/17            Price: £10
ISBN: 1 84057 865 3

Many Wastewater Treatment Works (WwTW) have MCERTS flow monitoring equipment at the works outlet only, which poses difficulties for assessing compliance with discharge permit conditions for Flow to Full Treatment (FFT).

We investigated the range of measurement arrangements currently in use, and their implications for FFT compliance assessment. Water companies and Regulators were consulted on their views regarding the potential (and need) for alternative FFT compliance assessment methods.

Two alternative methods (driven by flow and EDM data) were developed and applied. Approach 1 involved comparing durations of storm weir spill events and durations for which associated effluent flows exceed a FFT consent threshold. Approach 2 involved determining the level at which effluent flow reaches a plateau during storm weir spill events.

The feasibility of using static flow surveys to determine FFT compliance is also discussed.


National Screen Evaluation Facility - Inlet Screen Evaluation Comparative Report (1999–2015) 

Ref: 15/WW/06/10            Price: £10
ISBN: 1 84057 802 5

This report details the results of process performance tests performed at the National Screens Evaluation Facility, Chester-Le-Street STW, between March 1999 and December 2015 on a total of 59 Inlet Screens of different generic type, comprising 11 Bandscreens, 10 Finescreens, 27 Combined Screens, 8 Bar / Slotscreens and 3 Stepscreens, with nominal aperture size varying from 6 mm to 1 mm.

The testing establishes the effectiveness of each screen tested in terms of screenings removal (expressed as Screenings Capture Ratio - SCR) and also identifies screen hydraulic performance by establishing a head loss versus flow trend for each unit tested.

The report also offers a comparison of the various generic types of screens available to the industry.

Bathing Waters

Microbial standards and wastewater - what next?

Ref: 23/WW/11/15            Price: £10
ISBN: 978-1-84057-974-1

With current focus on water quality standards for rivers and bathing waters and incoming legislation to support further action, this project provides a review of latest research into microbial and viral pathogen standards in the context of the UK and Irish water sector. It provides an overview of existing bathing water standards and microbial standards for faecal indicator organisms and the recent Bathing Water Directive consultation and review.

Whilst the project recommends that the water sector retain existing microbial standards, which are aligned with best-science and latest World Health Organisation (WHO) and European Commission (EC) review, it considers opportunities and knowledge gaps - reviewing emerging focus on microbial standards, analysis techniques, current status and potential paths forward for the UK and Irish water sector.

This UKWIR project was led by Jacobs and supported by the Centre for Research into Environment and Health (CREH) at the University of Aberystwyth and WaterFutures, Australia.

Coastal and Estuarine Bacteria Loads for Source Apportionment

Ref: 16/WW/11/14            Price: £10
ISBN: 1 84057 817 3

The causes of poor bathing water and shellfish water quality represent a significant challenge for the UK water industry. This project has assessed the abundance of faecal indicator organisms (FIOs) in estuarine waters and sediments, with a particular focus on ‘viable but non-culturable’ (VBNC) bacteria, and on viruses. Two study areas were selected for sampling - the Ribble and Conwy estuaries. The results suggest that the VBNC fraction of FIOs in sediments may be significant, especially in the winter. Small quantities of Norovirus were only found at two sampling points in the Ribble, and in the winter only.  Results also indicated that cohesive sediments harbour more bacteria than non-cohesive sediments and the water column. This work has proposed practical recommendations for improving the existing monitoring and modelling framework, which will assist the UK water industry in making more efficient investment planning decisions to improve coastal/estuarine water quality.

Verification of Bacteroidetes Microbial Source Tracking with Emperical Ground Truth Data

Ref: 08/WW/11/12            Price: £10
ISBN: 1 84057 527 1

This study reports a 'field-scale' test of the emerging technique of microbial source tracking (MST). The project acquired 'ground-truth' data to test the operational utility of Bacteroidetes MST data. The work has resulted in a very significant data set which is believed to be the largest collected to-date world-wide. This allows a comparison of Bacteroidetes MST data with standard faecal indicator organism (FIO) concentrations in streams, effluents and bathing waters.
The study illustrated the need for any sampling programme to be designed to measure and characterise extreme temporal and spatial variability. Furthermore, it is imperative that the Bacteroidetes MST signal of any industrial discharge is fully understood prior to the interpretation of results from bathing beaches.
At this stage in the development of this tool, it would be imprudent to use the percentage human and/or ruminant contributions, as indicated by MST data acquired for a bathing water, as the sole or principal element in the evidence-base used to guide major expenditure decisions and/or regulatory action.

Evaluation of T90 Decay Rates for a Range of Micro-organisms Indicative of Sewage Contamination: Phase 2 - Building and Validation of Predictive Models

Ref: 07/WW/11/11            Price: £10
ISBN: 1 84057 440 2

The sunlight-induced inactivation of bacterial indicator organisms, F-specific bacteriophage and poliovirus 2 was investigated in a series of experiments.
An artificial light source was used to irradiate a range of sewage-spiked waters formulated to provide a pertinent range of temperature, turbidity and salinity combinations.  Inactivation curves were generated for each of the microorganisms (primary linear model).  Enterococci were the most resistant.
Although all primary model fits were excellent, secondary models (predictive equations) were fitted with varying degrees of success.  The faecal coliform data produced the best fit, but enterococci inactivation rates could not be modelled.  The heterogeneity of the enterococci group, their cell physiology and their propensity to occur in chains were identified as potential sources of variability in their response to light-mediated inactivation.
The validity of the predictive equations was assessed by producing inactivation data using natural waters and light and comparing them with predictions from the models.  For faecal coliforms, there was a consistent correlation between observed and predicted values.  No equivalent correlation was observed for the other microorganisms.  When the artificial light was replaced with natural sunlight, the fit was poor for all the microorganisms.

Preparation for a New Bathing Water Directive: Costing the Second Reading Amendments of the Proposed Revisions to the Bathing Water Directive

Ref: 06/WW/11/10            Price: £10
ISBN: 1 84057 398 8

A study into the potential costs of the new Bathing Waters Directive was undertaken in 2003. Following progress with the new Directive, standards have been clarified, and as such a further study was required to understand the cost implications of the final version of the Directive. 
The 2003 methdology was used, employing the Integrated Cost Estimate (ICE) costing model to predict potential costs associated with managing intermittent (wet weather) discharges.  Assumptions were made regarding continuous discharges, telemetry requirements and operational expenditure. 
Additional Bathing Water sampling data was integated into the study. 
The study delivered a range of potential costs, dependent on the standard to be achieved (Excellent, Good or Sufficient) and the delivery strategy (Spill Frequency or Risk Based Environmental Quality approach). 
This report discusses the approach, methdology and results, and presents conclusions and recommendations based on the findings.

Evaluation of T90 Decay Rates for a Range of Micro-organisms Indicative of Sewage Contamination: Phase I - A Review of Documented Historical Laboratory-Based Studies and Field Applications

Ref: 04/WW/11/9            Price: £10
ISBN: 1 84057 353 8

The study aims to describe the decline of microbial indicator organisms and enteroviruses in water under natural conditions in which all relevant variables, in particular solar radiation, are either measured or controlled. The first phase of the study was to carry out a comprehensive literature review to determine and finalise protocols for the experimental work.
From the review an experimental system has been devised involving the exposure of water samples containing a range of indigenous and laboratory cultured micro-organisms to sunlight generated by a full spectrum, solar simulator. The review identified key variables that affect microbial mortality - salinity, temperature and turbidity - and these variables will be manipulated in the laboratory to generate test mixtures that represent a range of conditions typical of UK coastal waters. The microbial mortality rates measured for the range of conditions tested will be used to formulate predictive equations for incorporation into a single inactivation model.

Preparation for a New Bathing Water Directive

Ref: 03/WW/11/8            Price: £10
ISBN: 1-84057-314-7

The European Commission has proposed a new Bathing Waters Directive which, when adopted, will have significant impacts on the UK water industry. These impacts have been assessed and a methodology for assessing individual costs developed. The major implications for the UK water industry will be to deal with intermittent discharges, with total costs ranging from £30 to £750 million depending on the approach taken to achieve compliance. Other issues need careful management too, for example the impression that the new Directive will give the public that bathing water quality is declining whereas in reality it is improving.

Review of the Fate of Enteroviruses and Indicator Organisms in the Environment

Ref: 03/WW/11/7            Price: £10
ISBN: 1-84057-293-0

The study reviewed methods for evaluating decay rates (T90s) for enteroviruses and the faecal indicator organisms and developed an experimental design to quantify T90s in the marine and freshwater environment. Numerous studies have been carried out on decay rates of bacterial indicator organisms, but not on enteroviruses. A protocol to evaluate inactivation of enteroviruses and indicator organisms under natural conditions has been proposed. Solar simulator experiments would provide validation data under natural sunlight conditions. If successful, an in situ study would be used to validate the in vitro data.

Review of the Fate of Enteroviruses and Indicator Organisms across Wastewater Treatment Processes

Ref: 03/WW/11/6            Price: £10
ISBN: 1-84057-292-2

Several wastewater treatment works were monitored to assess their performance in removing enteroviruses, coliforms, faecal streptococci and F coliphage across primary and secondary treatment processes. The processes selected were: activated sludge, biologically aerated flooded filters (BAFF), chemically assisted primary settlement (CAS) and oxidation ditch. The main findings were: · The operation and performance of a given process was probably site specific. · BAFF was potentially less effective than others in removing enteroviruses. · More enterovirus data were needed before firm conclusions on process performance can be made.

Relationships between Enterovirus, Salmonella and Bacterial Indicator Organisms in Bathing Waters

Ref: 02/WW/11/5            Price: £10
ISBN: 1-84057 275 2

Monitoring data collected for various purposes from 1986 to 1999, from 6 different sources and 22 bathing waters, were analysed to assess the relationships between enteroviruses and salmonella, and indicator bacteria (total coliforms, faecal coliforms and faecal streptococci). The data showed that within a single site there was no useful relationship between enterovirus and indicator bacteria and between sites it was week. There was a relationship between Salmonella and indicator bacteria within a site, although variable from one year to the next, and this was fairly strong between sites, season by season. The findings are consistent with the interpretation that indicators show the presence of faecal matter and hence indicate the risk of enterovirus or Salmonella being present in bathing waters. The actual number of pathogens or faecal indicators will vary according to the tidal state, the water turbidity and weather conditions. A large number of samples, backed by standardised analysis using validated methods, would be needed to obtain reliable information on which policy decisions or alternative disposal strategies could be based. The low frequency monitoring programme to show compliance with the Bathing Waters Directive 1976 would be insufficient for this purpose.

EC Bathing Waters Directive Enterovirus Research

Ref: 99/WW/11/1            Price: £10
ISBN: 1 84057 163 2

This composite report sets out the findings of the four separate literature reviews carried out to identify current knowledge and gaps which may exist on enterovirus. The individual abstracts for each review are set out below. Review of Sources of Enteroviruses in the Environment. The sources and inputs of enteroviruses in the environment are reviewed in the context of the EU Bathing Water Directive. The virology, epidemiology and prevalence of enteroviruses in water is discussed and the types of materials investigated for enteroviruses in the environment are also considered. Research requirements to determine better the significance of enteroviruses in waterborne disease are highlighted. Review of Methods for the Isolation, Concentration, Identification and Enumeration of Enteroviruses. Methods for concentration and detection of enteroviruses from water, with special reference to methods used in the routine monitoring of recreational waters in respect of the EU bathing Water Directive, are reviewed. Deta

Investigation of Bathing Waters Classification Approaches

Ref: 01/WW/11/2            Price: £10
ISBN: 1 84057 217 5

Two complementary approaches for classifying bathing water as part of a revised Bathing Water Directive were trialled in 1999 in the UK, France and the Netherlands. The report analysed the findings of the USEPA/ WHO and French Vulnerability Profile approaches leading to a revised bathing water monitoring and assessment protocol. The revised protocol incorporated microbiological water quality monitoring and analysis, a beach characterisation (sanitary survey) and beach management options. The protocol will be further tested during the summer of 2000 throughout the European Union.

Collection Systems

Treatment Options for Storm Overflows

Ref: 23/WW/22/7            Price: £10
ISBN: 978-1-84057-978-9

Storm overflows discharge diluted untreated sewage into the environment. The 2021 Environmental Act required companies, regulators and the government to reduce their environmental impacts.

Ofwat support this and require companies to reduce pollution incidents by 30% by 2025. Eradication by sewerage system separation could cost between £350 and £600 billion.

This project, contributing to Big Question 6 “How do we Achieve Zero uncontrolled discharges from sewers by 2050” provides an understanding of options and costs to address storm overflows.

A literature review identified commercially available treatment options for a number of different categories of storm overflows. The removal of debris using screens or separators could be viable at most sites but some systems require power.

Space and road access are factors when determining solutions and lack of power limits options available for organic pollution removal, disinfection and removal of emerging contaminants. Biological treatment (including nature-based solutions) is challenging due to the intermittent nature of storm overflows.

Performance of Storm Tanks and Potential for Improvements in Overall Storm Management - Phase 2

Ref: 07/WW/22/5            Price: £10
ISBN: 1 84057 469 0

Storm tanks have been an integral part of the sewage treatment process since the early 20th century, but to date however, their performance is poorly understood.  The introduction of the Water Framework Directive may see the need for water companies to quantify, both in terms of flow magnitude and quality, all intermittent spills to receiving water courses.  To do this it is required to better understand the pollutant retention efficiency of storm tanks.  This report looks at the designs of storm tanks that are currently in use and reports on a series of field evaluations and laboratory tests which have been carried out to improve understanding of the flow regimes and the pollutant retention in the most common designs of circular and rectangular storm tanks.  This data has been developed into a methodology which allows the prediction of the pollutant retention efficiency for a given design of storm tank under a range of conditions.  The outputs from the research comprise a final report, a technical reference manual (07/WW/22/6) and an MS-Excel based tool - sold together as a set for £300.

Sewer Network & WwTW Integration

Ref: 07/WW/22/4            Price: £10
ISBN: 1 84057 441 0

Historically poor planning in how sewer networks and WWTWs work together to protect water quality can lead to an increased risk of non-compliance with effluent standards. Designing and operating the system as a whole, in an intelligent manner, can bring benefits to water companies and environmental regulators alike. This UKWIR project applies novel modelling techniques to represent each part of the urban drainage system and better understand the risks and benefits of an integrated approach. It also reports on state-of-the-art enabling technologies for urban drainage system integration.

Performance of Storm Tanks

Ref: 05/WW/22/2            Price: £10
ISBN: 1 84057 467 4

The primary aims of the project were to seek to influence the AMP4 priorities of the Environment Agency and to ensure that future investment would achieve the  best value environmental benefit. Models of storm tank performance were developed to facilitate design and establish operational best practice, The outputs of the study were synthesized into a technical reference manual (Report Ref No 05/WW/22/3) supplied with this report. The project also examined technology based solutions that might serve as alternatives to storm tanks or, at least, enhance their performance. Further work is recommended to test and extend the methodology.

Estimation of Population Equivalent

Ref: 03/WW/22/1            Price: £10
ISBN: 1-84057-300-7

The UWWTD defines population equivalent (PE) as a measurement of organic biodegradable load which shall be calculated on the basis of “the maximum average weekly load entering the treatment plant”. This project was designed to test the statistical properties of such PE calculations and compare them with PE estimates used for other reporting purposes. In making these comparisons, an understanding of the factors influencing PE estimation was developed together with an insight into the varying interpretations adopted by different Water Companies. Relative to the other methods analysed, the UWWTD method for estimating PE showed major practical difficulties and inconsistent results.

Combined sewer overflows

CSO Research

National CSO Test Facility Wigan WWTW: CSO Screen Efficiency 1997 - 2005

Ref: 06/WW/08/14            Price: £10
ISBN: 1 84057 404 6

The report describes a comparative performance analysis of over 30 proprietary CSO / Overflow Screens tested in either a side weir CSO chamber, an extended stilling pond chamber or as stand-alone devices at the National CSO Test Facility, Wigan Wastewater Treatment Works.

Performance evaluations were made to assess the process efficiency of each screen, expressed as 'screenings retention value', at a series of inflow magnitudes and ratios of continuation flow to inflow.

The report gives a  technical description of each screen together with full test results and offers a comparison of equipment performance covering the various generic types of CSO screen currently available.

Intermittent Discharges - Environmental Review and Treatment Solutions

Ref: 02/WW/08/12            Price: £10
ISBN: 1 84057 256 6

Research was carried out into unconventional treatment options for Combined Sewer Overflows (CSOs) to find potential compact, reliable and cost-effective solutions to improve the quality of intermittent discharges. Future standards for discharges may dictate that storage or increased sewer capacity will not be satisfactory. No single wastewater treatment process is sufficient for all eventualities, but twelve processes were deemed technically and economically suitable for further consideration. The disadvantages and advantages of each of these processes in relation to treatment at CSOs were investigated. Most favoured processes are: ballasted lamella plate sedimentation for a large urban CSO; reed bed treatment for a small rural CSO; and chemical pre-treatment followed by UV disinfection for a CSO discharging into bathing waters. Pilot plant testing should be carried out in each case.

Characteristics of Sewage Particles

Ref: 01/WW/08/10            Price: £10
ISBN: 1 84057 230 2

The report combines the findings of two projects sponsored by UKWIR's CSO Research Group. One, by Sheffield Hallam University, carried out an evaluation process to categorise the different particulates in raw sewage and produce distributions of terminal velocities for each category. The second, by the University of Sheffield, evaluated the terminal velocity characteristics of the sewage particulates which enter the National CSO Test Facility at Wigan Wastewater Treatment Works, and monitored changes which occur due to the time of day and at different flowrates. The utilisation of the results of this project will increase confidence in the assessment of the separation efficiency of CSO chambers and unscreened novel devices. When implemented within design software, this will enable wastewater operators to adopt unscreened solutions, where appropriate, to minimise costs whilst satisfying aesthetic quality aspects of UCSO improvements.

Simplified Post Project Appraisal of CSO Performance

Ref: 01/WW/08/11            Price: £10
ISBN: 1 84057 235 3

In the past, the evaluation of combined sewer overflow (CSO) performance has been perceived as being expensive and difficult to achieve. Those costs and difficulties have militated against the widespread use of Post Project Appraisals. This study identifies simplified, low cost, methods of appraisal that are available for the performance of combined sewer overflows. These procedures should assist water service providers in: · demonstrating compliance with consent conditions, · demonstrating improvements in performance and · providing lessons to feed back into best design practices so as to improve the effectiveness of future investment and provide better value for money.

Flow Control Devices for CSOs

Ref: 99/WW/08/9            Price: £10
ISBN: 1 84057 186 1

The setting of a CSO structure is a primary design parameter. Ideally the flow control device which is used to restrict the flow to the treatment works should maintain a constant flow to the works irrespective of the depth of flow in the CSO chamber. This report describes a performance evaluation to evaluate the head discharge relationship for a conventional circular penstock, a Type CX Hydro International Hydrobrake flow control, a Steinhardt Vertical Hydroslide and a Biogest Alpheus Flow Limiter. The test programme was carried out at the National CSO Test Facility, Wigan Wastewater Treatment Works.

Scumboard Performance Analysis

Ref: 99/WW/08/8            Price: £10
ISBN: 1 84057 184 5

A performance evaluation was carried out to assess the influence on the total solids retention efficiency and the water depth in a side weir CSO chamber when changes were made to the position of a scumboard within the chamber. All tests were completed at the National CSO Test Facility at Wigan Wastewater Treatment Works. Similar measurements were made when a Rotomat ROK1 6mm mesh screen was installed horizontally to the downstream face of a side weir. Tests were completed with and without the scumboard in position for a series of inflow magnitudes and ratios of the continuation flow to inflow.

Event Logger Evaluation

Ref: 99/WW/08/7            Price: £10
ISBN: 1 84057 184 5

The report provides guidance in the selection, installation and use of event loggers for the assessment of combined sewer overflow performance. The effectiveness of different types of sensor has been tested in the field and the capability and ease of use of associated software has been assessed. Practical issues relating to installation, data retrieval and maintenance have been identified, together with logger capacity and cost of units.

Screen Efficiency (Novel Devices)

Ref: 99/WW/08/6            Price: £10
ISBN: 1 84057 183 7

This report describes the total solids retention efficiency of four innovative novel screen arrangements. These were, the Yorkshire Water Flexible Screen, the Thames Water Drum Screen, the Pipe screen with two different mesh types, and the North West Water Drum Screen. All tests were completed at the National CSO Test Facility, Wigan Wastewater Treatment Works. The report highlights the performance of each screen arrangement and identifies, where appropriate, the potential for the application of each screen in practice.

Using computational fluid dynamics to assess the impact of an anti- blockage device on the flow regime and solids retention efficiency of a stilling pond combined sewer overflow

Ref: 97/WW/08/3            Price: £10
ISBN: 1 84057 026 1

Uses a computational fluid dynamics model to investigate the flow pattern retention efficiency of a stilling pond combined sewer overflow chamber with and without an anti-blocking device. Examines the importance of the device's longitudinal position and of the related chamber's length.

Effluent Quality

Pollution Inventory estimator tool - update

Ref: 23/WW/25/8            Price: £100
ISBN: 978-1-84057-982-6

The European and UK Pollutant Release and Transfer Register mandates sewerage service providers to report on substances released to the environment. The Pollution Inventory estimator tool was created to aid regulatory reporting. However, it failed to operate in organizations that switched to Office 365. This project aimed to upgrade the tool, review its data using the Chemical Investigations Programmes (CIP) from England and Scotland, explore alternative development platforms and study how to include uncertainty in the returns.

A Procedure for Estimating Emissions of Pollution Inventory Substances from Wastewater Treatment Works

Ref: 14/WW/25/7            Price: £100
ISBN: 1 84057 716 9

The Pollution Inventory (PI) in England, Wales and Northern Ireland, and the Scottish Pollution Release Inventory (SPRI) is the mechanism by which the regulatory agencies (the Environment Agency, Natural Resources Wales, Scottish Environment Protection Agency and the Northern Ireland Environment Agency) compile information and provide public access to the quantities of specific substances discharged to water, air and land. The Pollution Inventory estimator tool enables Water Companies to report their annual returns via an auditable method in the absence of routine monitoring data for a substance of interest. A number of changes have been made to the list of substances to be reported in 2014 onwards and the estimator tool has been updated to reflect these changes. The procedure described is expected to be used in conjunction with the updated estimator tool (version 7.0), with reference to the User Guide, both of which are included.

A Procedure for Estimating Emissions of Pollution Inventory Substances from Sewage Treatment Works

Ref: 10/WW/25/6            Price: £300
ISBN: 1 84057 555 7

This project has provided an update of the original Pollution Inventory estimator tool and offers a cost effective method for the estimation of emissions of Pollution Inventory substance loads from sewage treatment works. The update allows water companies to estimate the returns for emissions to water and to air. The protocol described is expected to be used in conjunction with the updated Estimator Package (Version 6).

Identifying the Sources of Listed Substances in Diffuse Inputs to Sewage Treatment Works

Ref: 02/WW/25/2            Price: £10
ISBN: 1-84057-276-0

This study aimed to establish which listed substances are present in diffuse inputs to sewage treatment works and to evaluate relative contributions. Results indicated that several heavy metals arise predominantly from domestic sewage and for these there appears to be little scope to reduce inputs. Specific organic substances or groups are identified as likely to be present in domestic, service trade and runoff inputs. Results from pilot studies provide confidence in the UKWIR/EA pollution inventory protocol predictions for metals but confirm that there is considerable uncertainty regarding estimates for inputs of organic substances. Some changes to the protocol are recommended.

Identification of the Source of Priority Substances in Sewage Catchments

Ref: 02/WW/14/1            Price: £10
ISBN: 1-84057 251 5

The respective contributions from trade effluents, domestic inputs and other diffuse sources of sixty-nine specified priority substances, eg List I and List II chemicals under the Dangerous Substances Directive, received at and discharged from wastewater treatment works were evaluated. The main sources of those compounds arising primarily from domestic and diffuse inputs were identified. A desk-top protocol to identify sources and predict potential discharges of priority substances was developed and trialled for the catchments of Camberley and Countess Wear (Exeter) wastewater treatment works.


Environmental Impacts

Phosphorus speciation (ortho/total/SRP) - does it matter?

Ref: 17/WW/20/8            Price: £10
ISBN: 1 84057 843 2

Wastewater treatment works represent an important contributor to the phosphorus load in waterbodies. Analysis of data collected for the Chemical Investigations Programme indicated that metal dosing for phosphorus reduction has a significant impact on the relative proportions of Soluble Reactive Phosphorus (SRP) and Total Phosphorus (TP) in effluent. Where dosing is applied the SRP/TP ratio can be as low as 30%, but can also be highly variable. 

Analysis of field data from 10 catchments collected for this study indicated that phosphorus speciation in rivers is not the same throughout the catchment or throughout the year. The assumption that all reactive phosphorus is soluble is incorrect for areas with elevated iron, while higher in-river suspended solids levels lead to lower SRP/TP.    

It is recommended that a clearly defined methodology for the determination of phosphorus in effluent and surface waters is established, and the link between SRP and biota is explored further.   

Environmental Impact Assessment to Compare the Benefits of Achieving Tight BOD Standards Versus Increase in Whole Lifecycle Carbon

Ref: 14/WW/20/7            Price: £10
ISBN: 1 84057 726 6

There has been a drive by regulators to improve the quality of the aquatic environment, most recently in response to the Water Framework Directive. This has often been achieved through setting tighter permit limits on final effluent discharges from WwTW. Achievement of these tighter limits has been through increasing the degree of wastewater treatment, normally resulting in the use of higher carbon-impact treatment processes.
This project investigated the balance between the benefits to the aquatic environment from achieving tighter BOD standards and the costs, in terms of increasing carbon emissions as well as the impact on customers through increased bills. It also examined whether tighter BOD standards are an effective means of achieving water quality improvements, in terms of outcome and value for money. This report is intended to inform the debate with regulators (economic and environmental) with regard to setting future WwTW permits and price limits.
The report includes a spreadsheet Decision Support Tool that can be used to assess the impact of tighter BOD standards on river quality, carbon emissions and treatment costs.

Sustainable Integrated Catchment Management for Phosphorus

Ref: 14/WW/20/6            Price: £10
ISBN: 1 84057 711 8

Phosphorus is a major cause for failure of rivers and lakes to meet standards set out in the Water Framework Directive (WFD). This is a significant challenge in the UK that needs to be addressed across multiple sectors.
Through interviews, literature reviews and case studies, this project consolidated the current knowledge base into an accessible format. The report and appendices include reviews of current and emerging modelling tools for phosphorus and an evidence catalogue of measures available to different sectors to tackle phosphorus issues. Building on UKWIR's national scale eutrophication demonstration case of disproportionate costs for the WFD, this report sets out the relative apportionment of phosphorus sources for each waterbody and the expected cost-effeciveness of different measures scenarios including WwTW end-of-pipe solutions and agri-environmental measures.
A flexible, three-step approach is set out for water company staff to identify catchments most suitable for integrated catchment management. This is supported by a catalogue of map-based evidence, tools and worked examples.

Phosphorus Contributions from WwTW Discharges to Watercourses and their Long Term Impacts Relative to Other Sources

Ref: 12/WW/20/5            Price: £10
ISBN: 1 84057 652 9

The Water Industry is a major contributor to phosphorus discharges to the environment. By 2015 there will be over 650 wastewater treatment works (WwTW) in the UK with phosphorus consent levels driven by a number of EU Directives, including the Water Framework Directive. There has been considerable uncertainty with regards to derivation of the phosphorus environmental quality standard, which was initially derived as a supporting parameter to describe diatom ecological quality.
This project provides an increased understanding of the linkages between phosphorus speciation and ecology within the aquatic environment; the work undertaken included a combination of literature reviews, data collection and modelling using the Hampshire River Avon as a case study catchment.
The links between phosphorus and ecological status, as well as possible future permitting options, were assessed. Recommendations on how best the water industry can enter into discussions with the Environment Agency, to prevent incurring disproportionate costs with regards to phosphorus discharge reductions, have been made.

A Review of the Setting of Iron Limits for Wastewater Treatment Works Effluents

Ref: 11/WW/20/4            Price: £10
ISBN: 1 84057 582 4

Iron dosing at wastewater treatment works is used mostly to reduce effluent phosphorus concentrations in order to meet the requirements of European legislation. The existing iron Environmental Quality Standard (EQS) is currently under review. If the EQS value is reduced, a subsequent tightening of surface water discharge permits may result, which would have significant implications for the Water Industry.
This project assessed the effectiveness of current iron permits to ensure compliance with the receiving water EQS including an assessment of downstream impacys on water chemistry, ecology and sediment. Am examination of how a reduction in the EQS value might affect the Water Industry, in terms of the ability of existing technology to meet tighter permits as well as the potentially increased costs and carbon emissions was also undertaken. The assessment of available data collected from across England in addition to SIMCAT modelling showed that there is no evidence of significant increases in total or dissolved iron concentrations due to dosing for phosphorus reduction. Water quality data was also supported by ecological data and sediment data.
The report recommends that the Environment Agency reconsider the use of widespread iron permitting and that where permits are to be used, a change from a maximum discharge value to the use of a percentile and look up table is considered (based on river needs and taking account of dilution). The impact assessment provides the Water Industry with a robust case for engaging with the Regulators on future iron permitting policies, in particular demonstrating the lack of impact of iron dosing on downstream water chemistry or ecology.

SUDS - Increased Liability for the Water Industry - Phase 2

Ref: 06/WW/03/8            Price: £10
ISBN: 1 84057 417 8

This report is the second of 2 reports which investigate the liability risks associated with ownership of Sustainable Drainage Systems (SUDS). The first report carried out a broad evaluation of the issues, and the second study then investigated those which were perceived as being the most important. Key topics were assessed as being:

  • the risk of sediment in ponds and basins being classified as Hazardous and the disposal costs associated with their maintenance upkeep;
  • the risk of groundwater pollution from infiltration systems;
  • the risks associated with Health & Safety and also public nuisance;
  • the development of a SUDS protocol; and

the current state of existing software in being able to adequately represent SUDS.

Performance and Whole Life Costs of Best Management Practices and Sustainable Urban Drainage Systems

Ref: 05/WW/03/6            Price: £10
ISBN: 1 94339 743 9

This report documents the performance and whole life costs of stormwater practices in the U.S. (Best Management Practices) and UK (Sustainable Urban Drainage Systems) aimed at reducing the impact of urbanisation.

The BMPs/SUDS selected for evaluation in this study include retention ponds, extended detention basins, vegetated swales, bioretention, porous pavements, and various infiltration practices.

The study included literature and database reviews, hydraulic modelling, site investigations and development of a whole-life cost model.

This report provides guidance on the selection, whole-life costing, design, and maintenance of BMPs/SUDS, which will improve confidence in their use and performance and lead to a more widespread and appropriate adoption of these systems.

Implications of Potential New Measures and Standards Required under the Water Framework Directive for Natura 2000 Sites

Ref: 04/WW/20/1            Price: £10
ISBN: 1 84057 367 8

The study identified and assessed designated habitat sites that were dependent on water and might require more investment and action by the UK water industry. The additional measures identified were extra nutrient removal from discharges, extra BOD/SS/ammonia removal from discharges, and abstractions. The implications for individual water companies depend on local circumstances and measures already adopted or planned.

WW03 Forecasting The Deposition and Biological Effects of Excess Organic Carbon from Sewage Discharges for the Purposes of the Urban Waste Water Treatment Directive (DIR91/ 271/ EEC) BenOss Version 3

Ref: 99/WW/03/3            Price: £10
ISBN: 1 84057 169 1

BEN OSS Version 3 is a model, which will predict changes in the soft sediment benthic community in response to organic inputs. It produces an assessment of the amount of suspended solids (carbon) from a sewage outfall accumulating in the near vicinity of a domestic sewage outfall in terms of mass carbon unit area -1 time -1 . After calculating the amounts of deposition, the model then predicts what effect this will have on the benthic community.

Microbiological Inputs to the Environment from Sewerage and Sewage Treatment Works

Ref: 98/WW/07/1            Price: £10
ISBN: 1 84057 134 9

The pathogenic organisms found in sewage were reviewed, and those that should be tested include Salmonella, Campylobacter, Escherichia coli O157, Cryptosporidium, Giardia and enteroviruses. A field survey methodology will quantify the microbiological inputs into controlled waters from sewage relative to other inputs. The study area should be surveyed, and sampling sites should be chosen using evidence of sources of contamination and tracer studies. Following the presence of pathogens over two years will allow for variations in epidimiology and weather.

Forecasting the Deposition and Biological Effects of Excess Carbon from Sewage Discharges

Ref: 96/WW/03/1            Price: £10
ISBN: 1 84057

A model (BenOss) has been developed which predicts organic carbon deposition on the seabed and associated changes in soft sediment benthic communities. Modules take into account the hydrodynamic regime of an area, primary production and dispersion, settlement, resuspension and degradation of organic carbon. Although the model was developed to allow comparative prediction of the impact of primary and secondary treated sewage effluent on marine benthic ecosystems, it has a wider application and can be used to assess the impact of any organic matter discharge made to sea.

Intelligence Gathering

A Rainfall-Independent Approach to Calculating Treatment Flows at WwTW

Ref: 12/WW/23/9            Price: £10
ISBN: 1 84057 638 3

Most wastewater treatment works discharge consents contain a Flow To Full Treatment (FTFT) condition that states that all flows up to a given flow rate must receive full treatment. The FTFT has been set historically on the basis of a calcuation from flow components, but recent advances in data collection provide an opportunity for an appropriate setting to be estimated from flow data.
This project has developed such an approach that can be applied in the absence of rainfall data. The development of the new approach is described and its performance and limitations are assessed.
An approach for making allowance for future growth is described, based on maximum likelihood estimation as used in the regulatory water balance.
An approach for estimating infiltration flows is described, based on the hydrological technique of baseflow separation.

A Review of the Effectiveness of Mogden Formula Charging when Meeting Modern Sewage Treatment Works Consents

Ref: 12/WW/23/8            Price: £10
ISBN: 1 84057 628 6

The project investigated potential disparities between the current trade effluent charging mechanism (the Mogden formula) and the costs associated with trade effluent management and treatment. The study demonstrated that the Mogden formula continues to serve the purpose of equitably charging for the reception and treatment of trade effluents. Strong evidence supports the view that the approach to charging for ammonia should be reviewed by the Water and Sewerage Companies to ensure investment cost recovery in the future. There is also a potential future need to charge for the acceptance of trade effluent containing zinc.
Other issues addressed in this study include the accurate apportionment of charges where multiple substances are removed, sludge treatment cost recovery, the management of carbon footprint related costs and options for the risk management of accepting non-biodegradable Chemical Oxygen Demand from traders.

Wet Weather Definition and Impact on Planning and Regulatory Reporting

Ref: 11/WW/23/7            Price: £10
ISBN: 1 84057 614 6

This report identifies and reviews the wet weather spill monitoring and recording methods employed by the UK water and sewerage companies. Analysis was undertaken of spill, rainfall, and treatment works flow data along with completed questionnaires on the water companies' practices.
There are various protocols used for counting spills, which can result in significantly different totals. The report identifies issues that affect the usefulness of data for regulatory reporting and the need for improved access to rainfall data. It explores methods to determine the significance of spills recommending that a standard method should be agreed, and indicates that a common standard is required for spill event recording and for counting spills.

Better Regulation:Integrated Catchment Regulation

Ref: 10/WW/23/6            Price: £10
ISBN: 1 84057 566 2

This project was established to identify options for the application of better regulation which should seek to improve the balance between the environmental gains in water quality through permitting and the potential economic and environmental costs. A number of themes of research were advanced including seasonal consenting, real time control and the scoping of the future requirements for modelling.

Methodologies for Catchment Based Consents

Ref: 08/WW/23/5            Price: £10
ISBN: 1 84057 516 6

The project investigated how best to identify where, when and how wastewate treatment should be improved; and, how future performance should be monitored. A SIMCAT model was used to examine the potential benefits of catchment based consenting to the Water Industry. The results from twenty two scenarios, focused on changes to Water Industry assets, were compared in terms of WwTWs consents, overall catchment loads, and the length of river passing WFD standards. A key conclusion was that achieving full compliance with these standards would not be possible by consent tightening alone, nor would it be cost-effective. A catchment modelling approach to consenting is likely to produce less onerous consents that a single site approach. The full benefits of a catchment modelling approach will only be achieved by linking water industry asset management strategies, natural catchment characteristics and the potentil benefits of controls on other sources of pollution. It was recommended that a further range of model scenarios should be tested to show the wider benefits of an integrated catchment consenting approach and to illustrate 'best practice' for catchment modelling.

Characterisation and Treatment of Water Industry Waste Streams for Landfill Disposal

Ref: 06/WW/23/4            Price: £10
ISBN: 1 84057 414 3

Emerging legislation controlling the handling and disposal of wastes will have a major impact on the UK Water Industry. Landfill waste acceptance procedures have been introduced and non-hazardous wastes will require pre-treatment prior to landfilling from October 2007. Following a review of waste streams generated by the Water Industry, the main focus of this work was to provide a characterisation dataset on the priority waste streams of sewer grit and sewage screenings. A UK-wide sampling and testing programme was carried out to encompass the major sources of variability in these waste streams and provide basic characterisation information as required for landfill acceptance.  An assessment of existing treatment processes was undertaken to identify those that could meet pre-treatment requirements for landfill.

The Impact of Recent Changes in Waste Legislation on Sewerage Networks and Wastewater Treatment Works

Ref: 05/WW/23/3            Price: £10
ISBN: 1-84057-371-6

The landfill disposal route for many wastes will be increasingly restricted in future, affecting both wastes received by, as well as the disposal of wastes produced by, the Water Industry. Changes in legislation controlling the handling and disposal of wastes, both liquid and solid, will have an impact on the operation of sewerage systems and wastewater treatment works in the UK. This study identifies and assesses the impacts of these changes and recommends a number of mitigation measures that the Water Industry could adopt to reduce the impact of wastes discharged to the sewerage networks.

Comparison of Member State Implementation and Reporting of Five Waste Water Related European Council Directives

Ref: 01/WW/23/1            Price: £10
ISBN: 1 84057 245 0

Adoption and implementation of the Urban Waste Water Treatment, Dangerous Substances, Shellfish Waters, Freshwater Fish and Bathing Water Directives are compared between the EU Member States.

Intermittent Discharges

Pharmaceutical reduction at WWTW – cost and effectiveness

Ref: 20/WW/17/18            Price: £10
ISBN: 978-1-84057-901-7

The Urban Wastewater Treatment Directive is currently under review in 2020, with discussions being held as to whether advanced treatment for substances such as pharmaceuticals should be mandated to achieve a minimum reduction across wastewater treatment works, as is undertaken within Switzerland. This project looked at the implementation of pharmaceutical removal in Switzerland and its implications for the UK in terms of cost and effectiveness. Conclusions were drawn and recommendations made for the Water Industry and policy makers regarding pharmaceutical removal from effluent at wastewater treatment works. This knowledge will enable UKWIR and its members to inform, engage with and influence policy decision makers to ensure that any changes to the UWWTD are proportionate to the environmental benefit they will deliver.

A Guide to Modelling Intermittent Discharges

Ref: 14/WW/17/17            Price: £10
ISBN: 1 84057 749 5

This report provides an up-to-date and accessible guide to modelling intermittent discharges (i.e. combined sewer overflows, storm tanks and pumping station overflows). It is aimed primarily at water managers and asset planners in water companies who commission work from specialist modellers and authorise investment plans based on the results. It will also be useful for anyone who wants to gain an overview of current practice in the UK.

The guide describes a four stage process to modelling intermittent discharges: defining the problem, selecting an approach, applying the model, and analysing uncertainty. Each stage is broken down into a series of steps, which discuss critical decision points and summarise current good practice within the UK water industry.

A checklist at the end of each stage highlights key issues to be agreed between those responsible for building water quality models and those that use and interpret the model outputs.

Risk Based Prioritisation of Pharmaceuticals

Ref: 14/WW/17/16            Price: £10
ISBN: 1 84057 735 5

A range of pharmceuticals has been detected in the natural environment across the world. Concerns have therefore been raised over the potential effects of active pharmaceutical ingredients in the environment on human and environmental health and , over the past 15 years, a substantial amount of work has been undertaken to determine the occurrence, fate, effects and risks of pharmaceuticals in the environment. The aim of this project was to provide the UK water industry with a priority list of pharmaceuticals to indicate the contribution from wastewater treatment and help inform UK policy. Environmental exposure of the most used pharmaceuticals in primary and secondary care, plus some compounds considered an environmental hazard was compared to relevant environmental effects data and the compounds prioritised to identify those where attention should focus. The data was used to select pharmaceutical compounds for the second Chemical Investigations Programme and two priority lists of pharmaceuticals were generated for further consideration by the wastewater industry.

The primary priority list contained fifteen compounds that demonstrated an environmental risk during the prioritisation. The secondary list contained twenty-five compunds that demonstrated the possibility of environmental risk when associated prioritisation uncertainty was considered.

Alternative Approaches to Bacterial Reduction for WwTW Discharges: Phase 2 Field Trials and UV Desk Study

Ref: 13/WW/17/15            Price: £10
ISBN: 1 84057 698 7

EU Legislation has driven continuous wastewater discharge disinfection focussing on UV treatment. Reducing spills of intermittents by providing storage has been the normal approach.

This study proposes determining disinfection requirements on a site specific basis. The approach links the UV 'validated' dose to the microbial reduction achieved. The benefit of this approach is to achieve a reactor design validated against the microbial reduction required.

Benefits include: better targeted investment, supported by evidence; minimised capital and operating costs through better understanding of carbon costs associated with UV irradiation; demonstration of the methodology enabling production of site specific evidence to support a flexible, consistent approach to the disinfection of discharges; ability to meet revised bathing water directive targets and reduce the risk of EU infractions and beach closures; applicability of the protocol to intermittent discharge disinfection.

Catalytic Oxidation of Pharmaceutical Compounds in Wastewater Effluents

Ref: 13/WW/17/14            Price: £10
ISBN: 1 84057 689 8

Pharmaceuticals have been identified as a group of chemicals of concern in wastewaters due to growing regulatory pressures on river water quality. Recent assessments of advanced treatment technologies (Granular activated carbon and Ozonation) have shown them to be prohibitively expensive both financially and environmentally. This research investigated the ability of iron based catalysts (Fe-TAML) to reduce concentrations of a range of steroids, pharmaceuticals and personal care products in wastewater. Results demonstrate that using Fe-TAML catalysts is an effecive treatment for most of the steroids and pharmaceuticals tested. Following further optimisation, TAML may provide a low capex cost and flexible addition to wastewater treatment.

Emerging Technologies for Removing Pharmaceutical Compounds from Wastewater Effluents

Ref: 13/WW/17/13            Price: £10
ISBN: 1 84057 686 3

This study reviewed the potential of emerging technologies to treat pharmaceuticals of concern, as identified by the Chemical Investigations Programme steering group, and meet future potential obligations with more cost-effective, 'carbon friendly' treatment options than those currently available. The study identified eight technologies that could potentially effectively treat a wide range of pharmaceuticals. These technologies were evaluated with respect to integration within sewage treatment works and estimated whole life costs and ranked based on these criteria. The ranking identified three technologies (based on ultrasonic enhanced ozone oxidation, ultrasound enhanced ultraviolet radiation and carbon adsorbants) recommended for further investigation.

Alternative Approaches to Bacterial Reduction for WwTW Discharges: Phase 1, Desk Study

Ref: 12/WW/17/12            Price: £10
ISBN: 1 84057 640 5

This project studies a range of wastewater disinfection technologies in a search for a low carbon method for achieving bacterial reduction in discharges to Shellfish and Bathing Waters. It concludes that there are no alternative technologies currently available which could dramatically reduce the carbon footprint associated with disinfection.
This study shows that optimsed low pressure UV systems can provide one of the lowest carbon solutions. An evaluation of operational data provided from existing UV irradiation systems highlighted that there is significant potential to reduce power demand and associated operational carbon emissions in this area.
There is a wide variation in the way disinfection consents are set across the UK. Additionally, bacteriological data indicated that conventional wastewater treatment processes can produce effluents that are, on average, better than the guidance defaults for faecal coliforms. This could potentially provide the opportunity to reduce the onus on the downstream disinfection plant.
The importance of understanding the relationships between dose, log10 reduction, transmissivity and power was emphasised, in order to optimise the performance of UV disinfection systems while minimising carbon emissions. The report recommends field trials to test a methodology and protocol that might be used to establish an effective low carbon approach to disinfection.

Scoping Study for the Chemicals Investigation Programme (Dangerous Substances and Priority Hazardous Substances/ Priority Substances under the Water Framework Directive)

Ref: 10/WW/17/11            Price: £10
ISBN: 1 84057 561 1

Control over a wide range of potential contaminants is an important requirement of the Water Framework Directive. To meet this requirement, the CIP has been designed to investigate the management and control of concentrations of Priority Substances. This project was established to support the efficient implementation of the CIP. The detailed requirements of the CIP were developed and refined. Recommendations for analytical targets and approaches to sampling were made; protocols were developed for data capture, data processing and interpretation. The project facilitated the launch of the CIP in April 2010, which aims to identify cost effective and fairly apportioned measures to meet the requirements of the Water Framework Directive.

Source Control of Phosphorus from Domestic Sources - Options and Impacts

Ref: 09/WW/17/10            Price: £10
ISBN: 1 84057 526 3

Phosphorus is the single most important substance preventing good chemical status under the Water Framework Directive for inland surface waters of the UK. In order to avoid costly, ineffective programmes of measures it is necessary to fully understand the sources of phosphorus in the environment and its impacts. The project identified and quantified (including a field study) the contribution of human, tap water dosing, automatic dishwashing and laundry sources of phosphorus to wastewater treatment works and reviewed the options for source control compared with end of pipe treatment in achieving WFD objectives.

Water Framework Directive: Sustainable Treatment Solutions for Achieving Good Ecological Status

Ref: 08/WW/20/3            Price: £10
ISBN: 1 84057 501 8

Implementation of the Water Framework Directive is likely to necessitate tighter effluent consent standards and more extensive wastewater treatment. The pursuit of the environmental target of higher final effluent quality may result in adverse impacts on other important aspects of the environment, such as greenhouse gas emissions. This project has provided the water industry with a spreadsheet tool to assess the sustainability impacts of achieving good quality ecological status under the Water Framework Directive via different treatment processes. The tool will enable water companies to better estimate the implications on sustainability indicators, such as greenhouse gas (GHG) emissions, resulting from the Water Framework Directive. This will be important for companies in helping predict more accurately the GHG emission changes affecting their business in forthcoming years and what implications these changes may have on meeting requirements of future carbon trading schemes.

Ribble SIMCAT Pilot Study - Assessment of Relative Contributions and the Impact of Control Measures on Water Quality

Ref: 07/WW/17/9            Price: £10
ISBN: 1 84057 489 5

The Water Industry identified an urgent need to quantify the water quality benefits of Programme of Measures (PoMs) applied to Water Industry discharges at 'end of pipe' and other, more diffuse, sources of pollution. This project was established to identify both the most cost effective ways to reduce both point and diffuse source nutrient/metal loadings to a water body and to identify how they compare in terms of costs and benefits. The study addressed the following objectives: quantifying pollution loads from point and diffuse inputs to the catchment from water company discharges, agricultural and urban runoff; developing and calibrating a SIMCAT model of the Ribble Catchment for BOD, Ammonia, Phosphate, TON and Copper based on the identified pollution loads; and, assessing the water qualtiy benefits that would arise from a range of individual and in-combination PoMs scenarios for both point source and diffuse pollution control.

The study used a SIMCAT model to demonstrate how observed data for rivers and effluents plus inputs for urban and non-urban diffuse loads generated by other modelling approaches can be used to assess the apportionment of pollution from different sources across a catchment. The results from the study have been provided to DEFRA and used in the preliminary Cost Effectiveness Analysis for England and Wales. In many respects the issues facing the Ribble Catchment are not atypical of other large catchments in England and Wales. The approach developed in carrying out the Ribble Catchment study can be transferred to other catchments.

Dangerous Substances and Priority Hazardous Substances/Priority Substances under the Water Framework Directive

Ref: 07/WW/17/7            Price: £10
ISBN: 1 84057 464 X

This latest report in the research programme on Dangerous Substances and Priority Hazardous Substances/Priority Substances under the Water Framework Directive has developed the understanding of the sources, quantities, removal and risk posed to the Water Industry by these substances.
A detailed field study of six wastewater treatment processes, and a laboratory study investigated the removal of key Priority Substances in a range of potential tertiary treatment technologies. Whole life costs for the end of pipe treatment of substances has been estimated. The results have been applied to inform the choice of appropriate control measures. The environmental impacts of end-of-pipe treatment have also been determined.
Sold as a set with 07/WW/17/8: Basis for a Programme of (Chemical) Investigations to be Carried Out by the Water Industry During the AMP5 Period

Dangerous Substances and Priority Hazardous Substances/ Priority Substances under the Water Framework Directive: Initial Report: A Comparison between Options and Costs for Source Control Versus End-of

Ref: 07/WW/17/6            Price: £10
ISBN: 1 84057 435 6

The work reported here is an extension to the UKWIR WW/17 project and has been co-funded by UKWIR, OFWAT, the Environment Agency and Defra. The report provides an overview of the environmental, social and economic implications of tackling pollution at source (for the substances for which Environmental Quality Standards are likely to be introduced under the Water framework Directive) compared with installing additional sewage treatment. The study has taken into account existing and proposed legislation to ensure that cost projections take into account, and reflect the current, medium-term (2015) and long-term (2027) percentage reductions in emmissions required to comply with the WFD.

Priority Hazardous Substances, Trace Organics and Diffuse Pollution (Water Framework Directive): Urban Catchment Study and Assessment of Diffuse Inputs

Ref: 04/WW/17/3            Price: £10
ISBN: 1-84057-334-1

This report has been produced as part of a research programme to improve the water industry's understanding of the presence of priority substances in sewage. Foul water and runoff samples were taken from locations in housing estates, the town centre and a light industrial estate in an urban catchment. Results confirm that certain groups of priority substances arise from diffuse sources, including housing estates, and are ubiquitous in wastewater. Substances are identified which would cause most concern to the water industry if proposed EC sludge limits and draft water quality standards being proposed in the Water Framework Directive are implemented.

Priority Hazardous Substances, Trace Organics and Diffuse Pollution (Water Framework Directive):Treatment Options and Potential Costs

Ref: 04/WW/17/5            Price: £10
ISBN: 1-84057-333-3

This is the final report of the WW17C research programme which aimed to improve the water industry's understanding of Water Framework Directive priority substances in sewage. The results of sampling studies from earlier stages of the programme are summarised and used, in conjunction with a review of the fate of priority substances in wastewater treatment, to assess potential treatment costs. If end of pipe treatment is required as the main control measure for priority substances then, based on the quality standards being proposed, the additional whole life cost for England and Wales alone could be in excess of £6billion.

Priority Hazardous Substances, Trace Organics and Diffuse Pollution (Water Framework Directive): Surface Water Drains and Intermittent Discharges from Sewer Networks

Ref: 04/WW/17/4            Price: £10
ISBN: 1-84057-332-5

This report has been produced as part of a research programme to improve the water industry’s understanding of the presence of priority substances in sewage. Discharges of priority substances from surface water drains, domestic septic tanks and storm and emergency releases from sewer networks were assessed. The dilutions that are required to meet EQS are generally fairly low. In some cases discharges may occur during storms before river flows have built up. However, it is probable that in many cases additional control measures may not be merited based on considerations relating to priority substances alone.

Priority Hazardous Substances, Trace Organics and Diffuse Pollution (Water Framework Directive): Screening Study and Literature Review of Quantities in Sewage, Sludge and Effluent

Ref: 04/WW/17/2            Price: £10
ISBN: 1-84057-322-8

This report has been produced as part of a research programme to improve the water industry’s understanding of the presence of priority substances in sewage. Priority substances were analysed in samples taken from 30 wastewater treatment works across England and results have been compared with a comprehensive literature review. This study highlights the fact that certain groups of priority substances arising from diffuse sources are ubiquitous in wastewater. Substances are identified which would cause most concern to the water industry if proposed EC sludge limits and draft water quality standards being proposed in the Water Framework Directive are implemented.


Alternative permitting Approaches

Ref: 24/WW/23/11            Price: £10
ISBN: 978-1-84057-996-3

The project aims were to understand how other countries and environmental regulators approach permitting and consider these approaches to the UK and Ireland. This was achieved by completing the following activities:

  • Data and information were gathered from water companies on any current alternative permitting regimes.
  • Real-time data was considered as an opportunity to develop alternative permitting solutions.
  • Establishing how permitting for longer term investment decisions can be improved.
  • The presention of potential permitting options for consideration by environmental regulators.
  • Global approaches to permitting were reviewed, including contact with experts in Singapore, the USA and Switzerland.
  • Current alternative approaches in use in the UK and Ireland were reviewed in consultation with the Environment Agency and the water companies.
  • Alternative permitting opportunities of real-time monitoring technologies in the UK and Ireland were reviewed, followed by consideration of opportunities to amend permitting timescales.
  • Alternative approaches compared with the current permitting approach were explored and assessed against a number of criteria.


Role of Wastewater Process Control in Delivering Operating Efficiencies

Ref: 13/WW/21/16            Price: £10
ISBN: 1 84057 678 2

Improved control and optimisiation of wastewater treatment processes offers the potential for significant energy, chemical and carbon savings. In recent years, Advanced Process Control (APC) technologies have been trialled and installed by water companies and it is anticipated that the use of these systems will increase in the future. Using case studies and theoretical models, this project examined the impact APC may have on the receiving water, addressing concerns by the regulator relating to discharging less variable effluent with a potential increased load.

The Relationship between Per Capita Consumption and Wastewater Flows

Ref: 12/WW/21/15            Price: £10
ISBN: 1 84057 660 X

Water saving measures may have an effect on per capita consumption (PCC) and hence on the volume of wastewater generated (DWF); however the relationship between PCC and DWF is not fully understood. Modification to WwTW design criteria without defining the relationship introduces environmental risk and/or potential premature expenditure by water utilities.
The aims of this study were to understand and quantify any relationship between PCC and DWF; to understand any implications for WwTW process design; and offer guidance relating to the integration of water resources and wastewater planning.
The study analysed data from two catchments during implementation of a universal metering programme (UMP). It found that the relationship between per household consumption (PHC) and flow returned to sewer (G) was a function of house type and/or socio-economic group, and season. Water demand modelling suggested that universal water metering should reduce DWF by an amount which depends upon catchment characteristics. However, no significant reduction in household water use from pre-UMP levels was observed.
Reduced catchment flows were shown by modelling to have only small effects on WwTW discharge compliance and hence, no changes to existing design criteria for wastewater treatment processes are recommended,

Economic Level of Service for Sewer Blockages

Ref: 10/WW/21/14            Price: £10
ISBN: 1 84057 568 9

Over 160,000 sewer blockages are reported each year in England & Wales; or about 0.5 blockages per kilometre of sewer per year. These lead to a wide range of service failures including property flooding and pollution. About 75% of the blockage management activity is in reaction to failures, although the amount of proactive work to prevent blockages has increased in recent years.
This report provides guidance in recommended reactive and proactive approaches to blockage management including newly emerging techniques. Improved reactive blockage management techniques include better blockage clearance tools and technologies for inspecting the sewer after clearance to identify residual problems. Innovative proactive techniques include programmes of regular cleansing, level monitors and automatic flushing devices. There is also a strong role for Network Protection Officers to discourage the discharge of material that can cause blockages.
The project outputs include a strategic optimisation tool (BELS) that can be used to identify how to achieve either the least cost to the company to achieve a target level of service or the best value level of service considering costs to the company, customers and other stakeholders.

Evaluating Process Based Control as a Management and Regulatory Tool for the Water Sector

Ref: 10/WW/21/13            Price: £10
ISBN: 1 84057 554 9

The Environment Agency's new Operational Risk Appraisal (OPRA) approach offers the water sector and the EA an opportunity to develop Process Based Control (PBC) principles as an alternative to final effluent quality monitoring as a means of regulation. This project provides the water sector with information on the likely nature and impact of the proposed changes in regulation and points the way to the establishment of an agreed and cost effective approach to PBC. The report covers: the Regulator's position and expectations; current PBC practice within the UK water sector and beyond; a review of potential parameters and types of PBC; a comparison between compliance with existing regulatory sampling and continuous monitoring; and practicalities, cost benefits and scenarios.

Investigations into Flow Regimes at Sewage Treatment Works (Parts 1 & 2)

Ref: 08/WW/21/11            Price: £10
ISBN: 1 84057 493 3

UKWIR commissioned a three part project, investigating flow regimes in sewerage networks and at sewage treatment works.

Part 1 of the project set out to determine if the measured (Q80) DWF at sewage works can be related to the theoretical industry standard formula PG+I+E, using a set of explanatory variables.

Part 2 looked at how flow to full treatment (FFT) is currently set within the industry and investigated viable alternatives to the current 3PG+I+3E theoretical definition from both a reulatory and design standpoint. This included a specific evaluation of the role of infiltration. Following on from this, part 2 then set out to develop a methodology for evaluating the total (flow / load) impact of a sewage works on the receiving environment to provide an alternative impact based methodology for setting FFT.

Part 3 of the work reviewed previous work on understanding infiltration (including inflow) and its impact on the sewage works and sewer system, From this, it set out to establish robust and reliable techniques for identifying where high infiltration flows affect levels of service for a sewage works or sewer system, along with the associated causes. To address level of service deficiencies, the project also included associated technical guidance on where and when each of the methods would be appropriate and practical, including an associated cost benefit toolkit, to allow whole life costing of potential solutions.

This report covers Parts 1 and 2 of the project and is supplied together with 08/WW/21/12 (Part 3) for £100.

Best Practice for Flow Data Flagging

Ref: 08/WW/21/10            Price: £10
ISBN: 1 84057 479 8

Water companies are required to measure, and report to the Environment Agency, the volumes of effluent discharged from wastewater treatment works. This data is used for assessment of compliance with consent limits and broader catchment management. As well as the numerical data, the Agency has stipulated that flags relating to the quality of that data should also be reported. This project was commissioned by UKWIR, and supported by the Agency, to assist with the development of rules for flagging and reporting flow data. The report sets out a robust , practical methodology for flagging flow data that is acceptable to the Agency and ensures that data are reported to a satisfactory level of quality. It starts from the premise that water companies are collecting 15-minute data for this application, though it is acknowledged that this is not always the case and the implicatiosn of other approaches are discussed. The project also provides an understanding of how incomplete flow information affects the calculation of daily flow values and reported statistics, such as dry weather flow.

Dangerous Substances in Discharges: Setting Consent Conditions and Assessing Compliance

Ref: 07/WW/21/9            Price: £10
ISBN: 1 84057 429 1

Applying Maximum Limits (MLs) to Dangerous Substances (DSs) in Wastewater Treatment Works (WwTWs) effluents poses problems. This report describes work for UKWIR and the Environment Agency to quantify effluent variability and propose consenting alternatives.

A three-element alternative is proposed: a 95%ile for routine control, a 99.5%ile to address the skewness of DS distributions, and an absolute maximum for legal reasons. The performance of each element is investigated.

The Project Steering Group recommends the following approach, the practical implications of which are described in the report:

Limits on each DS at a WwTW:

  • A Lower-Tier 95%ile, assessed every calendar year by Look-up Table (LUT).
  • A Middle-Tier 99.5%ile, assessed annually on a 5-calendar-year basis by LUT.
  • An Upper-Tier absolute maximum (an agreed multiple of the Middle-Tier limit).

Applied to pooled DSs at a WwTW:

  • Compliance with all Middle-Tier limits, assessed on an annual 5-calendar-year basis by LUT.

The Efficacy of Natural Wastewater Treatment Systems in Removing Faecal Indicator Bacteria

Ref: 05/WW/21/7            Price: £10
ISBN: 1-84057-385-6

This project sought to determine the efficacy of natural systems in removing faecal indicators The most effective systems achieve Escherichia coli concentrations in the range 102-103 cfu 100ml-1 which is comparable to UV treatment. However, there is little data on attenuation during normal changes in flow. The systems studied included a horizontal reedbed, vertical reedbeds (which were relatively immature), a lagoon  and integrated constructed wetlands (ICW).  E. coli dry weather attenuation rates across the plants were found to vary between 70.2% and 99.8%. Corresponding wet weather attenuation varied between 55.8% and 99.9%. For enterococci, the dry weather attenuation varied from 61.12% to 99.8% and the wet weather attenuation varied from 3.9% to 99.8%. E. coli was attenuated more than intestinal enterococci. The integrated constructed wetland produced the highest attenuation of faecal indicator organisms followed by the retention lagoon, then the horizontal reedbed with the vertical reedbed producing the lowest attenuation.

Alternative Measures of Sewage Treatment Works Dry Weather Flow

Ref: 05/WW/21/6            Price: £10
ISBN: 1 84057 496 8

The current definition of sewage treatment works Dry Weather Flow (DWF) gives results with high year-on-year variability and cannot be calculated for a large proportion of data sets.

A wide range of alternatives are assessed against agreed selection criteria using over 3,000 works-years of validated flow data and nearly 2,000 works-years of associated rainfall data. A number are found to perform significantly better than the current definition, with percentile methods giving the best overall performance, and the 20th percentile of daily flows agreeing well on average with the summer DWF calculated by the existing method.

The implications of a change in definition have been assessed with regard to a wide range of issues, including consent compliance, funding via the Price Review, other consented flow parameters, and design.

The report provides a sound analytical basis for discussion and agreement between companies and regulators as to the preferred future approach.

A Literature Review of the Efficacy of Natural Systems in Removing Faecal Indicator Bacteria

Ref: 05/WW/21/5            Price: £10
ISBN: 1 84057 375 9

Two wetland types have been distinguished according to the presence of a free water surface. This feature determines the extent to which key processes, including oxygen diffusion and the balance of removal mechanisms between sedimentation and sieving, will operate. Removal of faecal indicator organisms and pathogens has been represented as a two step process, where initial retention is followed by elimination. Short-term by-pass and channelled flow, which might occur during storm-events, represents a potential problem to operational efficiency. Despite this fact, almost no intensive, event-based, sampled data exist. The majority of studies rely upon infrequent (weekly or longer) paired sampling of influent and effluent flows which are likely to be biased towards more stable flow conditions. Few data quantify seasonal changes to FIO and pathogen populations within individual wetlands. Thus, the principal data gap is event-based faecal indicator flux assessment to assess impacts on 'protected areas' such as bathing waters.

Detecting and Responding to Sewer Blockages

Ref: 04/WW/21/4            Price: £10
ISBN: 1-84057-347-3

The report considers the occurrence and causes of sewer blockages and reviews current management practice in the context of regulatory developments. A general specification is provided for a blockage detection system, including requirements for installation, maintenance, safety, reliability and cost. Potential monitoring parameters are reviewed and available sensor technologies are considered with particular focus on level and pressure monitoring. Communications options are reviewed, including systems architecture and telemetry integration. A methodology is described for assessing the costs and benefits of alternative approaches to blockage management, and calculations are provided in a spreadsheet. The cost benefit analysis is applied to eight case studies. An assessment is made of the market for sewer blockage detection equipment. The report concludes that subject to further development by suppliers and successful field trials, on-line detection of sewer blockages offers a technically feasible and cost-effective approach to the management of sewer blockages and their consequences.

Measurement of Low Flows at Wastewater Treatment Works (WWTW)

Ref: 01/WW/21/1            Price: £10
ISBN: 1-84507 237 X

By 2005 the Environment Agency policy on flow measurement will require the Industry to measure wastewater treatment works flows >= 50 m3/d with an uncertainty of +/- 8%. This project was designed to evaluate a range of technologies under typical installation and operating conditions on a small works, to determine their ability to meet the requirements of the policy and establish limits of detection and accuracy under a range of flow conditions. The outputs from the work would will both inform discussions with the EA on the policy and support the Industry in determining the most appropriate choice of measurement system.

Virus Sensitivity of the Plaque Assay Technique

Ref: 01/WW/11/4            Price: £10
ISBN: 1 84057 250 7

Bovine, ovine and porcine enteroviruses were inoculated into liquid culture of BGM cells. Several strains grew and were further analysed for their plaque-inducing potential in BGM cells. None of the bovine strains induced plaque formation but one porcine and one ovine strain produced clear plaques after three days incubation.

Evaluation of Matrix Effect during the Analysis of Enteroviruses in Wastewater, Natural Waters and Sediments

Ref: 01/WW/11/3            Price: £10
ISBN: 1 84057 249 3

The recovery of virus from wastewater was good and was not affected by the individual matrix. The recovery of virus from sediments was poor and related to the physical properties of clay and sand. Natural waters had a variable recovery of virus that may relate to the matrix. Further research is identified to investigate the factors governing recovery from sediment and natural water.

Nuisance Controls

A Framework for Cost Benefit Analysis in Odour Control Projects

Ref: 08/WW/13/9            Price: £10
ISBN: 1 84057 517 4

The report sets out a framework for undertaking cost benefit analysis of odour abatement measures at waste water treatment works. It describes different research approaches for valuing the user benefits of odour abatement, based on research at six case studies sites in England. Benefits were assessed through stated preference techniques (both willingness to pay and willingness to accept formats), and a revealed preference assessment based on house price values. The reduction in odour emissions at each of the sites was predicted using odour dispersion modelling techniques. The report sets out a recommended method for undertaking cost benefit analysis, using a willingness to pay approach, which was the only method to produce a statistically reliable valuation of benefit. A worked example is provided, along with other recommendations on further development of analytical techniques in this area.

Best Practicable Means (BPM) - A Guidebook for Odour Control at Wastewater Treatment Works

Ref: 06/WW/13/8            Price: £10
ISBN: 1 84057 415 1

This Guidebook has been written specifically to assist Wastewater Treatment Works (WwTW) operators to select the means to abate nuisance caused by odour from their works. It provides guidelines for an odour management hierarchy, ranging from prevention to treatment and also provides a framework for selecting Best Practicable Means (BPM) according to local circumstances. It is one of a series of documents giving guidance on odour control at WwTW and should be read in conjunction with Defra's Code of Practice (CoP) on Odour Nuisance from Sewage Treatment Works.  It describes factors that influence the generation and impact of odours from WwTW and provides guidance for dealing with complaints and reducing emissions through the adoption of both baseline, and where necessary, more expensive enhanced measures.

Odour Standards for the Wastewater Industry

Ref: 04/WW/13/6            Price: £10
ISBN: 1-84057-341-4

The scientific literature and documented case studies relating to odour nuisance from wastewater treatment processes have been reviewed, with a view to establishing a sound basis upon which a workable odour standard could be promulgated by the UK water service providers. A review and assessment of the current legislative controls over odour in England and the devolved administrations was also conducted, including examination of recent and ongoing legal actions. It is concluded that further work on human exposure-response relationships for wastewater odours would be needed in order to support development of a specific odour standard. At the present time, there is insufficient scientific evidence to allow confident adoption of an odour standard. Recommendations are included for possible future research work to support the further development of odour standards for wastewater treatment in the UK; together with an evaluation of risk-based assessment procedures and a detailed whole-life cost assessment.

Odour Control in Wastewater Treatment - A Technical Reference Document

Ref: 01/WW/13/3            Price: £10
ISBN: 1 84057 246 9

Malodours arising from sewage treatment and sludge handling activities can provoke customer complaints and lead to adverse media attention. In extreme cases they can affect the quality of life of those people who work or live close to the source. The UK water and wastewater service provides (WSP,’s) take the issue of odour seriously and recognise that the prevention and control of malodours is an essential part of the wastewater service. They have identified a need for a credible, reliable source of information that they can access for guidance on the subject of odour control. This Technical Reference Document (TRD) satisfies that need, providing in a single report comprehensive up-to-date source of information on odour control measures available to WwTW operators. The TRD consists of two parts. Part 1 describes the principles of odour formation, measurement and management. Part 2 describes in detail the practical methods available to control odours in wastewater treatment. The two parts togethe


Impact of Intermittent Discharges on the Microbiological Quality of Shellfish

Ref: 07/WW/18/1            Price: £10
ISBN: 1 84057 438 0

Laboratory and field investigations examined sewage effluent impact on microbiological shellfish hygiene parameters (faecal indicator organisms). Shellfish types examined were: wild mussels (Mytilus edulis) (all investigations) and Pacific oysters (Crassostrea gigas) (laboratory only).
The investigations demonstrated rapid uptake of organisms following contamination, producing flesh concentrations exceeding those recommended for human consumption (>46,000 Escherichia coli/100 g). Decay functions were fitted to subsequent depuration patterns.
In microcosms, mussels showed: (i) higher concentrations following contamination and (ii) more rapid depuration than oysters. Concentrations in flesh were correlated with those in overlying water (r>0.87). In the field, response was similar irrespective of overflow spill magnitude. Depuration was slower and statistical relationships between concentrations in shellfish and overlying water were weaker (r<0.66).

Treatment Processes

Plastics received by the Water Industry & how best to tackle them through source control

Ref: 22/WW/06/12            Price: £10
ISBN: 978-1-84057-959-8

This project contributes to the understanding of the types and quantities of plastic items (>6mm) commonly received at Wastewater Treatment Works (WwTW) inlets and those leaving Combined Sewer Overflows (CSOs).

Inappropriate flushing of items such as wet wipes, cause the majority of the 300,000+ blockages to the UK and Ireland water industries and up to £100 million in costs per year. Many of the items found contain plastic.

The research began with a literature search to find out the quantity and types of ‘plastics’ collected at WwTW inlets and leaving CSOs. It then identified how best to control these plastics through ‘source control’ measures, including policy interventions, behaviour change campaigns and voluntary industry actions.

The research will therefore allow the water industry to develop a strategy for targeting source control of plastic items. This will ultimately reduce operational costs and the amount of plastic entering the environment via our activities, and hence help to protect the circular economy and our bio-resources.

Engineering Biological Wastewater Treatment for The Removal of Hazardous Chemicals from Activated Sludge Plants

Ref: 17/WW/04/19            Price: £10
ISBN: 1 84057 847 5

The aim of this project was to assess if biological treatment processes at wastewater treatment works could be engineered to improve the efficiency of hazardous chemicals (HCs) removal. 

In this case, the effect of the engineering process parameters Solids Retention Time (SRT), Hydraulic Retention Time (HRT), temperature on microbial diversity were studied to identify those conditions that were most conducive for microbial degradation of HCs.

National Screen Evaluation Facility - Inlet Screen Evaluation Comparative Report (1999–2015)

Ref: 15/WW/06/10            Price: £10
ISBN: 1 84057 802 5

This report details the results of process performance tests performed at the National Screens Evaluation Facility, Chester-Le-Street STW, between March 1999 and December 2015 on a total of 59 Inlet Screens of different generic type, comprising 11 Bandscreens, 10 Finescreens, 27 Combined Screens, 8 Bar / Slotscreens and 3 Stepscreens, with nominal aperture size varying from 6 mm to 1 mm.

The testing establishes the effectiveness of each screen tested in terms of screenings removal (expressed as Screenings Capture Ratio - SCR) and also identifies screen hydraulic performance by establishing a head loss versus flow trend for each unit tested.

The report also offers a comparison of the various generic types of screens available to the industry.

Wastewater Screenings Management

Ref: 15/WW/06/9            Price: £10
ISBN: 184057 767 3

Over ninety percent of waste water screenings are currently landfilled and disposal costs are rising. Screenings production has risen in recent years due to increasing population, improved screening methods and an increase in the use of so called 'flushable' wipes. Data collected for this project indicates that around 98000tpa (wet basis) is collected from WwTWs in the UK.

This project has collected new data on screenings production and composition which can be used to identify appropriate and beneficial management options. The approach described in the report allows the practical issues and applicability of selected treatment options to be assessed to ensure sound investment in process technology or screenings management solutions. Background data is provided on a wide range of relevant processes and technologies.

The Excel spreadsheet included with the report can be adapted with new supplier and cost data and used as a support tool for investment and management decisions.

National Screenings Treatment Equipment Test Facility - Screenings Treatment Equipment Evaluation - Comparative Report (2010-2014)

Ref: 15/WW/06/8            Price: £10
ISBN: 184057 754 1

This report details the performance evaluation of a total of 12 Wastewater Screenings Treatment Equipment units of different generic type (comprising 2 Screw Compactors, 9 Washer Compactors and 1 Tank Wash System) conducted at a purpose-built facility (now known as the National Screenings Treatment Equipment Test Facility - NSTETF) at Netheridge STW, Gloucester (Severn Trent Water).

A comparison has been made in terms of equipment condition, operation and maintenance, but the major report output is related to equipment process performance, where a single-figure comparator has been developed to meet a specific industry need / request. This is the Screenings Treatment Factor (STF) which designers, purchasers and specifiers will be using in a similar way to how the established Screenings Capture Ratio (SCR) is used to compare Inlet Screens.

Optimising the Balance Between Primary and Secondary Treatment - Report

Ref: 15/WW/04/18            Price: £10
ISBN: 184057 755 X

Realising financial value through energy generation from treatment of sewage sludge and optimising operational performance for wastewater plants are two key drivers for water utilities. Optimising the treatment process requires a balance of increased primary solids removal, reduced load on secondary treatment processes, and assessment of effect on biogas yield from treatment of those solids.

Outputs from optimisation studies will provide information to assess the business case for investing in operational activities to improve the biogas yield. UKWIR commissioned the development of a model that enables changes in primary sludge solids capture to be quantified. The model is a spreadsheet tool which allows the assessment of the impact of operational changes to primary treatment processes.

Site operational data are necessary to configure and validate the model, to establish the baseline conditions against which projected variations to the primary treatment process can be assessed. The model was tested (trialled) on two working UK WwTWs.

Economic Assessment of Management Options for WwTW Wastes

Ref: 07/WW/06/6            Price: £10
ISBN: 1 84057 450 X

Sewer grit and sewage screenings are generated in the preliminary stages of wastewater treatment, and most of this waste is currently landfilled. Increases in landfill disposal charges, the imposition of the landfill tax and the reduction in void space have made landfill disposal increasingly expensive. This project identified the costs and main feasibility issues associated with alternative disposal options. It quantifies the mass of grit and screenings produced by the UK water industry currently and the costs of disposal. It is intended to inform water industry members of the threats to continued landfill and to assist them in planning to respond proactively to those drivers. This is principally achieved through the assessment of alternative options and the economic assessment, delivered in the format of a worksheet model designed to be adapted and tailored by individual water companies. This report will aid the water industry in the forthcoming PR09 planning process.

Screenings: Quality and Quantity

Ref: 00/WW/06/3            Price: £10
ISBN: 1 84057 211 6

The report investigates the proportions and characteristics of the constituents of screenings and reviews them in the context of the EC Landfill Directive and the UK Government’s Waste Strategy. Quantifiable measures of screenings quality are developed, for use in determining the cost of disposal routes. The measures of screenings quantity and quality are used to produce a performance specification for screenings handling plant. Methods of collecting, preparing and testing samples are developed.

Technical Study into Heat Sinks in Wastewater and Sludge Treatment

Ref: 12/WW/05/6            Price: £10
ISBN: 1 84057 621 9

The objective of this project was to investigate the potential for exploiting the Renewable Heat Incentive (RHI), a government economic incentive, as an additional revenue stream within the wastewater and sludge treatment industry.
The main finding of the project is that there is scope for the industry to benefit from RHI. The most likely application would be through the export of surplus biomethane into the national gas grid. Favourable indicators include a proximity to a suitable medium pressure gas connection and high net gas yields from advanced anaerobic digestion.
Exporting heat from sewage treatment facilities is unlikely to offer an opportunity, as the capacity threshold stipulated in the RHI is lower than the potential output of all but the smallest digesters found in the industry.
Export is also unlikely from the industry's current generation of incineration plants, which have been designed primarily as a means of sludge disposal rather than as energy generators. However, it is possible to envisage a new generation of incineration plants, configured to meet good quality combined heat and power criteria, which could act as a source of heat for some facilities.

The Performance of Sustainable Wastewater Treatment Works Solutions

Ref: 11/WW/04/16            Price: £10
ISBN: 1 84057 585 9

The records of 12 UK water companies were searched for performance data repating to sustainable wastewater treatment technologies, and questionnaires regarding maintenance and compliance were sent to site operators.
Data were received from 79 treatment systems representing 10 water companies. The majority reated to tertiary constructed wetland systems (CWS), which were found to consistently reduce mean concentration of BOD, ammonia and suspended solids, though the final effluent concentration of ammonia often varied widely. Some removal of metals, naturally occurring oestrogens and total nitrogen, was observed, though removal of phosphorus and the synthetic oestrogen EE2 was not evident. Performance of primary and secondary treatment CWS, partially aerated logoons, tertiary lagoons and grass plots was also discussed.
The level of maintenance was investigated. Around half of the tertiary CWS in the study were found to have required the media to be replaced, at a mean age of 8 years.

The Implications of Cold Weather on Nitrification Treatment Processes

Ref: 11/WW/04/15            Price: £10
ISBN: 1 84057 580 8

There are concerns that, as a result of revisions to ammonia effluent quality requirements, WwTWs in the UK may not be able to comply with more stringent permits for ammonia during extreme cold weather conditions when their nitrification capability is compromised by the reduced activity of nitrifying bacteria. This project collated data on cold weather performance to re-assess the consented 'unusual weather' clauses and thereby allow informed debate with environmental regulators over revised exemption criteria or seasonal consents. The study has shown that in the UK, unusually low wastewater temperatures occurred at over 35% of WwTWs during the winters of 2008/09 and 2009/10. When wastewater temperatures dropped below 5deg C, WwTW effluents exhibited increases in ammonia concentrations of up to 2 mg/l N. The recovery period from a low-temperature process upset takes between 1 week and 1 month and has the potential to place many UK WwTWs at risk of consent failure following a cold weather event. Other EU countries tend to apply relaxed ammoniacal-nitrogen standards to take account of cold weather. This puts the UK Water Industry at a major disadvantage compared to other EU countries.

Maximising the Value of Biogas: Volume 1 - Summary Report

Ref: 09/WW/05/4            Price: £10
ISBN: 1 84057 534 4

Biogas is often used by the UK Water Industry in combined heat nad power plants. However, advances in technologies for biogas production, treatment and use, combined with new financial incentives for different forms of renewable energy, may make alternative uses of biogas more attractive. Optimisation of biogas production and uses will also help the water industry mitigate its climate change impacts.
This study appraises the costs and benefits of current and potential uses for biogas, including combustion in CHP plants, conversion to biomethane (for use as a vehicle fuel or injection into the national gas grid), conversion to hydrogen and use in fuel cells. The study also reviews options for increasing the quantity and quality of biogas produced by the anaerobic digestion of sewage sludge. Finally, the study reviews the policy, regulatory and economic constraints and opportunities associated with each potential use.
The study analysis and findings are presented in two volumes: a Summary Report and a more detailed Technical Report. Presentation slides summarising the study findings are also provided.
Sold as a set with 09/WW/05/5 for £200

Disinfection of Storm Sewage Discharges

Ref: 05/WW/04/11            Price: £10
ISBN: 1-84057-378-3

The review evaluated the evidence for the satisfactory performance of storm sewage disinfection techniques as an alternative to increased storm sewage storage and subsequent return to full treatment.  A review of the effectiveness of a range of alternative disinfection technologies, including pre-treatment requirements, has identified UV irradiation technologies and chlorination as the technologies with the greatest potential.  Interpretation of a storm sewage trial (United Utilities) and a microwave UV irradiation trial (Yorkshire Water) were included in the review.
A specification for conducting a field-scale practical demonstration of the efficacy of candidate pre-treatment/ disinfection technologies has been prepared following discussion with manufacturers.

Sustainable WWTW for Small Communities Vol I: Sustainability and the Water Industry (Part Of Set)

Ref: 04/WW/04/9            Price: £10
ISBN: 1-84057-323-6

Sustainable development is of particular interest to the water industry which finds itself having to comply with increasingly stringent standards for wastewater effluent quality whilst being pressed to minimise the cost to the consumer. Treatment processes suitable for achieving these high standards of effluent quality are likely to involve increased costs, energy usage and greenhouse gas emmisions. These issues are particularly relevant to small wastewater treatment works which are more likely to be located in remote situations where the application of complex high-energy processes are probably inappropriate. Volume I discusses the background to sustainability considerations within the water industry and presents the framework for the methodology. Sold as a 2 Volume set for £400 with Volume II 04/WW/04/10

Review of Wastewater Disinfection Treatment Strategies - Final Report

Ref: 03/WW/04/5            Price: £10
ISBN: 1-84057-288-4

A review was undertaken to identify recent UK and international developments in wastewater disinfection technologies for both continuous and intermittent discharges. Existing technologies include UV irradiation, submerged membrane bioreactors (MBR), chlorination, ozonation and constructed subsurface flow reedbeds. Potential new technologies include electro-disinfection, ultrasonics, gamma radiation and microwave irradiation. Each technology has been assessed and its possible advantages and disadvantages identified. A more detailed review has been undertaken for technologies that represent the most viable alternatives for operational application within the next 5 years, concentrating on developments in UV irradiation, MBR, ozonation and constructed subsurface flow reedbeds.

Metals Removal and Treatment

Ref: 03/WW/04/4            Price: £10
ISBN: 1-84057-279-5

This study delivers a comprehensive review of the issues facing the Water Industry resulting from tighter regulations on the discharge or disposal of metals. The main benefits of the study are to provide technical and financial information to avoid ineffective investment and to ensure that appropriate treatment is properly funded. A comprehensive technology review is included that details the performance of conventional and other effluent and sludge treatment techniques. Alternatives to treatment are identified and costs compared to those of the treatment options.

Impact of Extended Storage on Sewage Treatment

Ref: 02/WW/04/3            Price: £10
ISBN: 1-84057-266-3

Increased extended in-sewer storage may have consequential effects on downstream treatment plants. Problems may occur due to septicity, odours, screen blinding, high hydraulic loads, overloaded bioreactors, and increased sludge volumes. Nonetheless, consent failures are unlikely provided sewer and downstream treatment systems are designed and operated accounting for the potential interactions.

Tightening WwTW Emission Standards - A Review of the Treatment Technologies And Their Impact On Climate Change

Ref: 02/WW/04/1            Price: £10
ISBN: 1-84507 259 0

This study examines the feasibility of meeting tighter effluent quality standards at wastewater treatment works. The impact of these tight standards on energy use, greenhouse gas (GHG) emissions and costs has been assessed. Performance of the different treatment technologies has been compared with respect to effluent quality, energy use, GHG emissions, costs, land use and sludge production. The results indicate that tight effluent quality standards can be achieved but there is a significant penalty in terms of increased GHG emissions and costs. The results of the study should allow the water industry to enter into an informed debate with the regulator regarding effluent quality and climate change issues.

Urban Pollution Management

Extending SAGIS to include catchment statistics analysis and reporting in preparation for PR24

Ref: 23/WW/02/17            Price: £600
ISBN: 978-1-84057-983-3

This project has delivered a spreadsheet tool that extends the capability of the SAGIS-SIMCAT system by providing a range of informative catchment-based statistics at different spatial scales, including metrics relating to ‘fair share’. 

Incorporating the agreed ‘fair share’ allocation methodology within the SAGIS-SIMCAT system streamlines data management. It also ensures a consistent source of information and supports water industry measures to ensure it is compliant with ‘fair share’ regulations and is not made responsible for addressing pollution from other sectors.

The project included a range of other SAGIS-related scoping studies and investigations, namely; i) adapting the current sector data in the model from load inputs to concentration inputs thereby enhancing the credibility of data on non-effluent chemical sources, ii) a meta-analysis of modelled outputs on PFAS chemicals, and iii) exploring the implementation of other tools to model environments not covered by SAGIS-SIMCAT that could be used in conjunction with SAGIS-SIMCAT.

There may be a significant reduction in the price of this report if you have already bought a copy of the previous SAGIS report.  Please contact the UKWIR office for assistance.

Wastewater Re-use

Waste Water Re- use

Ref: 98/WW/09/1            Price: £10
ISBN: 1 84057 135 7

Recycling and reuse of wastewater is reviewed. Four key applications for reuse of recovered water are identified: (a) domestic, (b) irrigation, (c) aquifer recharge, and (d) industrial. These applications are discussed in turn, with reference to required water quality and preferred technologies. Key data from individual papers are appended.