Research on Aerobic Composting Using Biological Enhanced Dewatered Sludge

Abstract

Abstract. Aerobic composting experiment was carried out by using bio-enhanced dewatered sludge as raw material. The experiment was carried out on the aerobic composting of sludge and crop conditioner. Studied on the changes of physical and chemical indexes in the process of composting. The results showed that the temperature of stack rose rapidly in the initial stage, it could be maintained at high temperature stage (>50℃) for 5 days; at the end of composting, the water content of stack decreased to 37.35%, the sludge reduction effect was remarkable; the organic matter of the stack was 40.28%, pH value rose to 7.33; ammonia nitrogen and total phosphorus increased by 548.4% and 60.6%, compared with those before composting, the nutrient index has been improved; sludge physical and chemical indexes, nutrient indexes and pollutant indexes all meet the regulations, the composted sludge could be used for landscaping. IntroductionBy the end of March 2016, more than 3,910 sewage treatment plants have been built in towns and cities in China, sewage treatment capacity has reached 167 million m³/d, the sludge was produced in 3,000-4,000 t/ years (the rate of water content was 80%). It was expected to 2020, sludge production in China will reach 6,000-9,000 t/ years. If the large number of sewage sludge can not get standardized disposal, it was likely to cause secondary pollution to the environment, therefore, in order to avoid the environmental pollution, sludge must be disposed [1]. Biological enhanced dewatered of sludge originated from microbial hydrometallurgy [2], compared with the conventional physical dewatered technology, it had the advantages of high removal rate of heavy metals, the organic matter and calorific value of the sludge almost unchanged, and the operating costs was low. After microorganism dewatered treatment, the water content of sludge cake, which produced by pressure filtration of excess sludge was less than 60%. In this study, we used rice husk and straw as conditioning agent and bioenhanced dewatered sludge cake for aerobic composting [3], studied on the effect of composting, and appraised the feasibility of applying composted sludge in landscaping.