Research On The Technology Of Solar-assisted Aerobic Composting For Disposing Rural Domestic Waste

In recent years,the production of rural domestic waste has been increasing,and the composition becomes complex,which has caused tremendous pressure to the rural areas of soil,water and air environment.The problem of disposing the rural domestic waste has become a prominent contradiction in the process of building a well-off society in an all-round way.Therefore,it is of great practical significance to explore a kind of good economic and adaptable way to meet the needs of rural areas to solve the problem of "garbage encircle the village",which conforms to the trend of green sustainable development.In this paper,a high efficiency and low energy aerobic compost reactor was designed based on rural reality.Solar energy was used as energy source and the hot air supply was used to solve the problem that the composting process was greatly affected by low temperature climate.On the basis of studying the treatment efficiency of aerobic compost reactor,the optimum ventilation conditions were optimized,the microbial succession rules under different compost conditions were analyzed,and the maturity extent and fertilizer efficiency of composting products were evaluated according to the relevant standards.The cost of the process was analyzed in combination with the preliminary design of the project as well as the feasibility of the process in the treatment of rural domestic waste was analyzed from the view of reduction and resource utilization,in order to provide a strong basis of operation parameters and theoretical support for the large-scale bio-fermentation chamber project with ventilation.The main results were concluded as follow:1.The content of kitchen waste and garden waste in Fuyang Yongchang rural solid waste sorting plant was about 76%,and the volume weight was basically maintained in the range of 347.72kg/m³-417.96kg/m³.Select the natural compost as the control and control the self-designed aerobic compost reactor running under the conditions of ventilation rate at 0.1m³/min m³ and ventilation frequency of 10min per hour to carry out the performance test.Based on the analysis of the indexes of temperature,pH,EC,E4/E6,C/N,moisture content,organic and ash content,seed germination index,the results showed that utilize the compost reactor can significantly accelerate the rate of aerobic composting and decomposition process,and improve the maturity of the compost.Also,the weight-loss ratio and capacity reduction rate were respectively 22.95%and 18.54%higher than that of the natural control at 30th day.2.Compare the effects of reactor treatment at different ventilation quantity,ventilation frequency and ventilation temperature,so as to optimize the ventilation parameters to enhance the reactor operation.The experimental results showed that the optimal operating parameter of ventilation quantity was 0.2m³/min m³ and the ventilation frequency was 20min every 2h;and under this circumstance the pH value was 7.89,the EC was less than 2mS·cm^-1,the moisture content was reduced by 25.02%,the C/N and organic content respectively decreased to 14.78 and 47.83% as well as temperature,absorbance,BDM,three states of nitrogen and other indicators were all in good condition at the end of the composting.The weight-loss ratio and capacity reduction rate could reach 54.36%and 66.14%,respectively.Moreover,it was feasible to solve the problem of low temperature and low efficiency of composting by heating air to 30-40? in the low temperature environment in winter.The temperature above 50? can maintain 8 days and the weight-loss ratio and capacity reduction rate was up to 64.89%and 68.57% respectively,the seed germination index reached to more than 120%,the other indicators all showed that the treatment effect and the extent of reaction were far better than that of the non-heated treatment group and the compost had better maturity.3.The results of high-throughput sequencing showed that the diversity of microbial increased with the composting,and the most obvious was the hot-blast air group.During the high temperature phase,Firmicutes and Ascomycota were enriched and became the dominant strains in each reactor,but the degree was different.According to the analysis of the succession of fungi and bacteria,ventilation can effectively promote the reproduction and decomposition of aerobic micro-organisms,heating can significantly improve the process of composting and the maturity of the material at stable phase.It may be related to OPB54,Sphingobacteriia,Flavobacteriia and other bacteria,which had the ability to degrade lignocellulose and polysaccharides,as well as the dominant fungi such as Galactomyces,Sordariales and Pichia,which can promote the maturity of material.4.According to the physical,chemical and biological indicators and fertilizer test results,the product of aerobic compost reactor had achieved a good maturity state,and the overall quality was fine.Total nutrient content was up to 8.08%,organic content was around 50%,the content of various types of heavy metals and fecal coliform was at the low level,and the roundworm mortality rate reached 100%.Besides,all the other indicators can almost achieve the requirements of "Organic fertilizer" and "Urban waste agricultural control standard except for the high moisture content ".Therefore,the compost can be used for organic fertilizer or landscaping soil and realize resource utilization.5.Combining with the preliminary design of the practical project,the feasibility analysis of the composting technology was carried out,which showed that the total operating cost of the forced ventilation static micropower aerobic composting system used in this experiment was about 8972 yuan per month,and the processing cost of the tonnage excluding the capital cost was only 29.91 yuan.However,if take the investment and construction costs into consideration by 15 years depreciation,it may cost 68.54 yuan per ton.In general,the operation and treatment cost of the process was completely affordable in rural areas,and it can also produce 90-120t organic fertilizer per month,which had environmental,economic and social benefits,and with good applicability to the vast rural areas.