Wastewater Forum Archive


Meeting 10th July 2002

Please note that for older reports some links will be to sites that are no longer active.

Updated revisions of the ROCKs on endocrine disrupters and on sewage sludge will be available very soon. These were first published in November 2000 and June 1999 respectively and whilst they remain excellent independent reviews, the Forum considers that it is important tat they be kept up to date.

A co-sponsored workshop is planned with WaPUG (Wastewater Planning User Group www.wapug.org.uk) on 26th September in Solihull to explore the question of predicting the routes of urban flooding. Urban flood route prediction – can we do it? We protect the flood routes (i.e. the flood plains) for the main rivers but when the capacity of subsidiary drainage is exceeded the streets and other routes become the subsidiary drainage in urban areas. The Forum and WaPUG consider that we do not have the modelling tools to take this is into account adequately when designing and permitting development in the built environment. The solution will be a combination of terrain modelling, fluid mechanics, hydrology, urban drainage, open channel hydraulics, computational fluid dynamics, data capture by remote sensing and meteorology. With the incidence of extreme weather events becoming more frequent this is of huge financial and quality-of-life implications. The objectives of the day are to:

If you know anybody who can make a positive contribution we should like to hear from him or her.

The Forum discussed the Environment Agency’s consultation on implementation of the Water Framework Directive. At first this was thought to be river basin management more or less as it has been practised and developed in the UK since 1984, but the process has become less pragmatic as it has metamorphosed into an EU directive. The objective of river basin management is to protect/manage the health of the rivers. The UK practice was to monitor and control the chemical quality, because these parameters are easy to measure, and the biological quality will be a reflection of the chemical quality. However the WFD requires direct assessment of the biological quality and a risk assessment to protect it. There are serious doubts about whether we have all the tools and knowledge to do either of these properly. In addition the timetable for completion of the risk assessments probably does not give time to do the work properly. For example we do not fully understand the causes of some changes in biodiversity and whether they are transitory or permanent. It is certainly a laudable objective but whether it is entirely practicable is another matter.

The Forum discussed an initiative to derive “welcomed” use of organic resources on land through a partnership open to all interested parties what will share information, and build trust, between partners and derive consensus on acceptable practise all the way down the line. This has been the subject of an Environment Agency funded scoping study that included a workshop, which was attended by about 80 people representing more than 55 organisations. The workshop gave unanimous support that using manure, biosolids, composted waste, etc. on land has to be a practicable option because members of the public do not want incinerators (rightly or wrongly) and landfilling is becoming increasingly difficult as the Landfill Directive is implemented. A partnership as envisaged was considered to be essential in order to achieve this. The general public might not have a great awareness of this issue but it is vital that the people and organisations that they trust as “gatekeepers” has an understanding and are part of deriving consensus on acceptable practise.

Dr Stephen Smith, Reader in Civil Engineering at Imperial College, London and Director of the Centre for Environmental Engineering & Waste Management gave a paper titled Supporting the sustainable use of sewage sludge: a research perspective. CEEWM has become one of the leading research groups on the use of organic resources on land. Some of the topics of concern are emotive, but it is important that we have objective scientific information on which to base policies. Hazards can be grouped as conservative and transient. The “heavy metals” are conservative, whereas pathogens and some organics, such as LAS are transient. The significance of even the conservative hazards is complicated by sorption reactions and transformations that can render them increasingly unavailable to biological activity. The concentrations of most of the hazards are decreasing as a result of reductions at source, though there is still room for improvement and greater diligence in some places. With the quality of modern wastewater biosolids it is technically impossible to have phytotoxicity. A note of caution is needed about product substitution in case the substitute has greater adverse environmental effect. Improving understanding of the value of nutrients is an increasing priority in order that these materials can be used for greatest benefit. The predictive capabilities of models for the major nutrients is improving and in the not-too-distant future it should be possible to have web-based agronomic advise that can be tailored to local situations. Dr Smith is author of the book “Agricultural recycling of sewage sludge and the environment” which was supported by FWR. This comprehensive and objective review, which contains about 1000 references, is now out of print but FWR still has a few copies available at 49.50 + p&p. It would be nice to find the resources to produce a second edition but in the mean time this remains an essential reference work.