1. Council of European Communities. 1991, Directive concerning urban wastewater treatment (91/271/EEC), Official Journal L135/40,30 May 1991.
2. The impact of EU and UK environmental pressures on the future of sludge treatment and disposal;Davis;J CIWEM,1996
3. Fundamentals of anaerobic digestion of wastewater sludges;Parkin;J Env Engineer,1986
4. Anaerobic digestion: effects on particle size and dewaterability;Lawler;Journal WPCF,1986
5. The role of natural extracellular polymers in the bioflocculation and dewatering of sludge (literature survey);Ryssov-Nielson;Vatten,1975