Research progress of in-situ reduction technology of sludge

The activated sludge method is currently the most widely used biological wastewater treatment process in the world. It operates stably, the effluent quality is better, and part of the generated sludge is effectively disposed of in a concentrated form. However, due to the status quo of emphasizing water over sludge and the gradual increase of wastewater treatment rate, residual sludge becomes an unavoidable by-product of the treatment process. This by-product not only significantly increases the total operating cost of wastewater treatment plants, but also carries a large amount of toxic biochemical residues in the environment. The issue of how to treat and dispose of sludge safely and economically has begun to receive attention. The in-situ reduction technology for the simultaneous treatment of wastewater and sludge has many advantages over conventional sludge disposal. Through the analysis and comparison of various treatment technologies of thermal, chemical, mechanical, and other biological processes, their ability to enhance sludge hydrolysis and their advantages and disadvantages are summarized.