Study on the Enzyme Activity Change during the Aerobic Composting Process of Sewage Sludge

Abstract

Compost is widely used for treating urban garbage and sewage sludge. The enzyme activity is one of the important parameters of microbial quantity and its activity intensity change in the composting process, and all of the biochemical reactions during the composting process are carried out with the enzymes involving. The composting progress and the material change are directly reflected by the enzyme activity. In Zhengzhou Bagang sludge disposal plant, sludge was mixed with straw to compost together and with the technology of high temperature solid state aerobic slot for sludge treatment. This study was done to research the tendency of peroxide enzyme activity, cellulose enzyme activity, pH, conductivity, moisture content in the process of compost. The result showed that at the beginning of the compost, cellulase activity increased first and then decreased gradually and tended to be stable. The catalase activity was higher at the beginning of the compost and at the period of temperature raising it was stable basically, then decreases quickly and after that it maintain on the lower level. The moisture content declined gradually during the composting process, and in the period of high temperature there are more moisture loss. PH increased at first, and with the temperature raised to high the pH decreased gradually and tended to be stable. Conductivity increased first, then decreased gradually to steady.