For instance, Louwe Kooijmans and van Velsen (1986) reported that start-up of UASB reactor seeded with digested cow dung manure for domestic wastewater treatment at 25 C required a period of 6 months. Another study Vijayaraghavan and Ramanujan (1999) described that sludge in anaerobic contact filter seeded with cow dung slurry was stabilized in a period of 160 days.