Sludge Quality

Polynuclear Aromatic Hydrocarbons in Sewage Sludge Amended Soil-Crop Systems

Reference: 03/SL/04/3
ISBN: 1-84057-316-3
Published Date: 15/12/2003

Sewage sludges can contain organic chemicals from a variety of sources at low concentrations. A previous report ( 02/SL/04/2 ) concluded that polynuclear aromatic hydrocarbons (PAHs) do not accumulate in the terrestrial foodchain and that a proposed EC limit value appears inappropriate. This report describes a study to address the issue. Worst case scenarios of sewage sludge being applied to the surface of grassland were investigated. Pot trials were also conducted with carrots and lettuce to investigate realistic or elevated sewage sludge application rates. The outcome of these studies was that typical UK sludges contain PAH concentrations above the suggested limits, precluding them from agricultural use. Evidence from this work suggests that the sludges pose no risk to the environment, animal or human health when applied under suitably controlled conditions.

Price: £15  

Organic Contaminants in Sewage Sludge Applied to Agricultural Land

Reference: 02/SL/04/2
ISBN: 1-84057-277-9
Published Date: 11/12/2002

Sewage sludges contain organic chemical contaminants from a variety of sources and at low concentrations. The European Union has proposed that limit values, relating to the application of sewage sludge to agricultural land, are established for some specific classes of compounds. This report presents a critical evaluation of the proposed EU limit values, examining how and why the standards have been derived, considering whether they are scientifically defensible, and the practical implications of trying to implement them. It is shown that the derivation of the proposed limit values has little scientific credibility. Further, it is shown that if the proposed limits are adopted for some chemical classes, the 'sludge-to-land' outlet will be seriously impacted, with little or no benefit to the quality of soils, crops and human exposure to the chemicals in question. The report presents a logical, step-wise approach for considering the fate, behaviour and significance of organic chemical contaminants in sludge-soil-foodchain transfer scenarios, which can be used to help derive scientifically defensible limits.

Price: £17  

Pentachlorophenol (PCP) and chloranil as sources of PCDD/ Fs to sewage sludge and sludge amended agricultural soils

Reference: 97/SL/04/1
ISBN: 1 84057
Published Date: 17/04/2002

The contribution of pentachlorophenol (PCP) and chloranil- based dyes and pigments to the dioxin (PCDD/ F) content of sewage sludges and the potential for PCDD/ Fs derived from these sources to persist in sludge amended soils and to trtansfer through the agricultural food chain is discussed. Sources, production and use of PCP and chloranil are described along with regulatory issues. Where possible, UK production, use and import statistics have been updated. The application of other types of organic amendments (eg farmyard manure), paper waste sludge and textile waste could represent important sources of PCDD/ Fs to agricultural soils. At present the application of these wastes is not subject to the same level of control as sewage sludge. There is very limited data available at present to quantify their current and future impact. Using a congener- specific pathways analysis model, the addition of sludge containing high concentrations of PCDD/ F congeners associated with PCP and chloranil- based sources does n

Price: £17