Sewage Sludge: Operational and Environmental Issues
Revised June 2016

This ROCK (Review of Current Knowledge) explains that sewage sludge is an inevitable consequence of wastewater treatment. The quantity produced has increased because of regulations requiring additional standards of treatment together with increasing population. The urban drainage system serves domestic and non-domestic premises and often carries surface drainage as well. In the future increasing emphasis will be given to recovering resources from wastewater, in addition to the public health engineering aspects of preventing waterborne disease and protecting the environment. Metropolitan rivers, such as the Thames, Mersey and Tyne, are the healthiest that they have been since the start of the industrial revolution; this is a tribute to wastewater treatment.

The ROCK reviews the benefits and hazards associated with the use or disposal of sludge. Some of the potential benefits are contributions to renewable energy, replacement of mineral fertilisers (especially phosphate) and soil structural improvement; hazards could include chemical pollutants and dissemination of disease organisms. There has been a massive amount of scientific research into these matters; the ROCK provides an objective review with 33 references.

Governments support the use of sludge on land where this is practicable and they have enacted legislation to prevent harm. Other means of use or disposal are controlled by other legislation. The ROCK reviews these controls and the succession of independent reviews to which they have been subjected. One of the challenges for society is the communication of technical information in order that public attitudes are informed by objective information rather than swayed by miss-information and emotion. FWRs ROCKs are intended to contribute to disseminating objective information.

June 2016 Fourth Edition (first published June 1999)

Copies of this report are available from the Foundation, price £15.00, less 20% for FWR members.

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