Impact assessment from sewage sludge

Sludge is formed during wastewater treatment. Wastewater may contain certain undesirable components, including organic, inorganic and toxic substances, as well as pathogenic or disease-causing micro-organisms. Sewage sludge is being generated in ever increasing amounts and the dilemma centers on how to find an environmentally acceptable way to utilize sewage. The treatment and disposal of sewage sludge is an expensive and environmentally sensitive problem. It is also a growing problem worldwide since sludge production will continue to increase as new sewage treatment works are built and environmental quality standards become more stringent. With some traditional disposal routes coming under pressure, and others such as sea disposal having been phased out, the challenge facing sludge managers is to find cost-effective and innovative solutions whilst responding to environmental, regulatory and public pressures. Recycling and use of wastes are the preferred options for sustainable development, rather than incineration or landfilling, but with sewage sludge this is not straight forward because of perceptions over contaminants, pathogens and its faecal origin, particularly by the food retailers. If future quality standards for sludge and the receiving environment are made too stringent, the agricultural outlet may become untenable for the water utilities resulting in sludge being disposed of by other means that offer the utilities greater operational and financial security, but which may be less acceptable in the long-term.