ANAEROBIC TREATMENT OF DOMESTIC SEWAGE AND WASTE-WATER

Recent UASB-pilot plant and full scale experiences show that anaerobic pre-treatment is feasible for sewage and domestic wastewaters in trop ical regions. This offers developing countries the unique opportunity to become completely self-sufficient in this respect. UASB-systems can be applied at very small and at very big scale, i.e. for off-site and (house and community) on-site treatment. Results obtained in pilot pl ant and full scale installations demonstrate that these systems are qu ite effective in removing and stabilizing organic pollutants at liquid detention times as low as 4 hrs, i.e. a BOD reduction up to 75-95 % c an be achieved, while an almost complete treatment can be accomplished by combining the method with a small aerobic lagoon. Instead of consu ming high grade energy, these systems produce energy. Moreover the exc ess sludge production is very low, while also the dewatering character istics of the sludge are excellent.