Study On Aerobic Composting Of Sludge Based On Recyclable Conditioner

The large-scale expansion of sewage treatment plants in our country has brought a lot of sludge garbage.On the one hand,sludge contains a large number of harmful bacteria and toxic substances.If they are not properly treated,they will easily cause secondary pollution and endanger human health.On the other hand,sludge contains rich nutrients such as nitrogen,phosphorus and potassium,which can be used as soil amendment if properly treated.Aerobic composting process has become one of the most widely used biological treatment and disposal methods in recent years,with harmlessness reduction and resource utilization of sludge.Although the traditional organic conditioners(such as sawdust,straw,straw,etc.)used in aerobic sludge composting can adjust the moisture content and C/N ratio of the compost and provide certain nutrients,there are some problems such as large storage area,high cost,difficulty in improving the physical structure of the compost,non-recycling and non-conforming to the concept of sustainable development,which limit the large scale of composting technology.But some inorganic conditioners can solve these problems very well,so if organic conditioners and inorganic conditioners can be used in compost,they can combine the advantages of various conditioners.Therefore,the purpose of this paper is to study the effect of a recyclable inert material(plastic ball)as a partial conditioner for aerobic sludge composting.The main contents and conclusions of this study are as follows.(1)In the aerobic sludge composting experiment,to study the feasibility of composting,plastic balls were used as a part of conditioners.In this study,the high temperature period of group A(without plastic ball),B(800 g sawdust + 200 g plastic ball),C(600 g sawdust + 200 g plastic ball)lasted 3,4 and 4 days,respectively,and the highest temperature of group B and C was 52.5 and 53.8 ? respectively,higher than that of group A(52 ?).The water contents of A,B and C groups decreased by 54.88%,54.96% and 68.48%,respectively.It could be seen that using plastic balls instead of some sawdust were more conducive in persistence of high temperature period of aerobic sludge composting,which can kill more harmful bacteria,reduce water content,and promote the harmlessness and reduction of composting treatment,so the experiment proved that this scheme was appropriate.(2)Based on the feasibility of sludge aerobic composting with plastic balls,the mixing ratio of plastic balls and sawdust was changed.The effects of plastic balls on sludge aerobic composting were explored by analyzing the changes of routine physical and chemical properties and nitrogen loss of composting materials during composting process,until the appropriate proportion of conditioning agent was found.In this study,the degradation rates of organic matter in group A(600 g sawdust + 350 g plastic balls),B(500 g sawdust + 350 g plastic balls),C(500 g sawdust + 400 g plastic balls)were C > A > B,and the microbial activity in group C was much stronger,which was more helpful to improve the efficiency of sludge composting.The total nitrogen contents in group A,B and C decreased by 15.77%,19.27% and 15.30%,respectively.Among total nitrogen loss in group C was the lowest,but the conservation effect of nitrogen was the best.And E4/E6 values at the end of composting were 1.88,1.85 and 1.70 in group A,B and C,respectively.What is more,E4/E6 values in group C were the lowest,and the maturity of compost products and the composting effect were higher.(3)On the basis of appropriate proportion of conditioners,different carbon sources(sucrose or glucose)were added during high temperature period,exploring their control effect on nitrogen loss during sludge composting,so as to optimize the existing composting scheme and improve composting efficiency.In this study,the dehydration rates of A(without carbon source),B(with sucrose)and C(with glucose)groups were 38.68%,44.83%,41.53%,respectively.The total nitrogen of B(with sucrose)group and C(with glucose)group decreased by 26.64% and 26.88%,respectively,which were lower than 28.01% that of the contrast group,indicating that the addition of certain sucrose or glucose could be effective.The dehydration effect and nitrogen retention effect of the sucrose group were better than those of the sucrose group in reducing the moisture content of the compost and nitrogen loss in the composting process.