Environmental Impacts

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

Reference: 17/WW/20/8
ISBN: 1 84057 843 2
Published Date: 07/10/2017

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

Reference: 14/WW/20/7
ISBN: 1 84057 726 6
Published Date: 02/06/2014

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

Reference: 14/WW/20/6
ISBN: 1 84057 711 8
Published Date: 17/02/2014

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.