Study On Influence Factors Of Sludge Reduction Process OSA System

Recently, there are more concern about the wastewater treatment. As a result, the deal efficiency and amount of treated wastewater increased much fast. Traditional activated sludge process is using most widely process because of its mature and availability, but this process bring out other problem-----excess sludge's treatment. There are many harmful component in sludge including pathogenic matter, heavy metal and residual organic matter, which could pollution the environment if the sludge doesn't treat properly. As environmental and legislative constrains increase, the disposal of excess sludge is strongly limited. To resolve the sludge problem, there are two directions. One is to promote the treatment technical which stabilize sludge. The other is to reduce the production of excess sludge during the wastewater treatment. It is hard to stabilize excess sludge completely. Because of the technical and economy limits, the sludge treatment can'not avaid the negative effect to the environment. In 1990's, a new idea were brought forward that is reducing the biomass production during the wastewater treatment. This paper reviewed the technical and the theory on sludge reduction of past and present, and emphasize the research on OSA system. This paper studies the influence to sludge reduction effect caused by sludge concentration (MLSSj), sludge retention time(tj) and temperature(Tj) in the uncoupling reactors in OSA process by both single-factor and orthogonal method. The study shows that the improving of MLSSj, tj and Tj can result in the decline of ORP value in uncoupling reactor , and sludge production yield has a linearity relationship with △ORP like Yobs=-0.0007△ORP+0.452 , and also with MLSSj, tj and Tj like Yobs=0.384-0.0265MLSSj-0.00155tj-0.00238Tj+0.00132 tj. Tj . This paper also found that the OSA process can reduce 58% sludge production relative to traditional activated sludge process when COD loading is 0.42 Kg COD/Kg MLSS .d-1, MLSSj=11 g/L, tj=11h, Tj=40℃. This paper also found that when the COD concentrion of influent was lower than 1000 mg/L, the OSA process still can reduce the biomass production , but the effect was slow down. When sludge loading changed from 0.52 g COD/ g VSS.d-1to 1.01 g COD/ g VSS.d-1, the reduce extend changed from 53% to 48%. As the reduction of sludge, the effect of wastewater treatment has been stabilized and even were better than reference process. This paper also found that OSA process has more anti-organic load ability than traditional activated sludge process. This paper's result is very helpful to spread the OSA process in China, which is well matched with the economic and environmental factors.