Research Progress of Sludge Treatment and Disposal with Microwave

The sewage sludge produced by municipal wastewater treatment plants contains a large number of unstabilized pathogenic microbes and other toxic and harmful substances. The sludge treatment and disposal is a widely concerned problem. This paper reviews the current state of the treatment and disposal for sewage sludge both at home and abroad. The technology of sludge treatment using microwave is discussed. Microwave is a high-efficiency heating technique,its use for sludge treatment and disposal can make quick sludge heating and hydrolysis,that will improve the sludge dewatering and anaerobic digestion capability. On the other hand,the microwave treatment technology does not involve any chemical agents and will not introduce any new pollutants or toxic substances into the sludge,therefore,will make the subsequent processing more efficient. Some representative sludge treatment technologies with microwave are analyzed,including the pyrolysis of sewage sludge by direct microwave heating to keep out of the air and to obtain gas,liquid fuel products; the disruption of sludge cell wall and extracellular substance using microwave heating to improve the biodegradability of sludge for anaerobic digestion; and the treatment of sludge by microwave together with other physical or chemical methods. The principles of these technologies are focused,and some proposals for the future research and development of the sewage sludge treatment using microwave are suggested.