PERFORMANCE OF ROTATING BIOLOGICAL CONTACTOR FOR TREATING SEGREGATED GREY WATER FOR REUSE S. Syed Enayathali ** and Dr. V.Nehru Kumar* ABSTRACT The laboratory model of two-stage Rotating Biological Contactor (RBC) which was used in the present study is a modified one, with a provision to vary the speed of rotating blades. Grey wastewater was used to study the performance of the modified rotating biological contactor. The reactor had four rotating blades in each stage, having the size of 300 mm x100 mm x 10 mm, attached perpendicular to the shaft. The experiment was conducted for different influent COD loads and different speeds of rotating blades. Among the different speeds of rotational blades in treating grey water, the rotational speed of 3 rpm was found to yield better percent removal of COD at 95.07% as maximum, where as against the rotational speeds of 4.5 and 6 rpm, the treatment efficiency is 95.04% and 94.96% respectively. Keywords: RBC, Rotating blades, Grey water, COD, OLR, I. INTRODUCTION Water usage in an Indian residential building is 4% for drinking, 4% for cooking, 41% for bathing, 22% for toilet flushing, and 15% for laundry; 14% for cleaning, sprinkling and other miscellaneous purpose. Wastewater segregation and treatment for reuse has become the best wastewater management option. Increasing the grey water reuse by lowering fresh water use for irrigation is an important step towards better environment and resource management. Grey water is a part of used household water which has not come into contact with toilet waste. Grey water produced can vary across each household according to the number of household occupants, ages, lifestyles, health and water use patterns. It contains waste that a household would normally wash down in drains. This content can vary between households, across different days and is dependent on daily household activities. Generally grey water contains soap, shampoo, toothpastes, cooking oils, laundry detergents, hair, and cleaning products. ** Ph.D. Scholar, Department of Civil Engg., Annamalai University, Annamalainager, Tamil Nadu ,India. * Professor and Director, Centre for Environment, Health and Safety, Annamalai University, Annamalainager, Tamil Nadu, India International Journal of Engineering Research & Technology (IJERT) Vol. 1 Issue 4, June - 2012 ISSN: 2278-0181 1 www.ijert.org