Wastewater treatment has become a necessity of the day as the world is in cancerous grip of water pollution and is facing a scarcity of potable water in many developing and undeveloped countries. Many techniques are used for the treatment of wastewater, and biological treatment of wastewater is one of these widely used techniques. Excess sludge production is one 296of the most serious challenges in biological wastewater treatment plants. Biodegradation of excess sludge is a commonly used method in biological treatment by anaerobic digestion. Anaerobic digestion is quite attractive waste treatment practice, where two objectives can be accomplished and these are pollution control and energy recovery. It is a suitable technology to treat not only solid waste but wastewater also.