Technology Research On The Synergistic Aerobic Composting Of Municipal Sludge And Kitchen Waste

With the increase of sewage treatment plants and the development of garbage classification,the municipal sludge and kitchen garbage produced are increasing year by year,which will cause serious impact if not properly treated and disposed.In this study,municipal sludge and kitchen garbage as raw material,the mushroom residue and wood chips as auxiliary materials.The effects of carbon to nitrogen ratio,bacterial agent type,ventilation mode and amount,and salt and oil content on the composting process were investigated,the physicochemical and biological indicators of products were systematically analyzed.The result is as follows:To explore the effects of different carbon-nitrogen ratio factors on synergistic aerobic composting,four experimental groups were set up in the experiment,the C/N ratios were X₁=25:1（without inoculants）,X₂=20:1,X₃=25:1,X₄=30:1,measured many indicators such as temperature and analysis.According to technical guidelines and specifications,after composting for 45 days for X₂,X₃ and X₄,the composting high temperature days met the requirements,and the GI of X₂,X₃ and X₄ were all greater than 80%,were non-phytotoxic.Taking the national and industry standards as the prescribed limits,it was found that only a small number of indicators did not meet the standards,but the reference sludge standards could be used as nutrient soil,and there were various needs for use,including land improvement and other aspects.In order to determine the optimal carbon-nitrogen ratio,the most influential factors were selected through SPSS analysis.The composting days above 55°C,moisture content,carbon-nitrogen ratio degradation rate and GI were determined as the evaluation factors for decomposing maturity.The grey relational method was used to evaluate the degree of decay.The results showed that the heap body X₃ is better,and the maximum correlation value is 0.761,which was better decomposed.Pot experiments found that X₃ plants were the best,with an average stem length of 18.6 cm and growing well.The carbon-nitrogen ratio factor was optimized by the response surface method,and the maximum response value of F was 0.687,and the corresponding total carbon,total nitrogen and mushroom residue were 42.635%,1.765%and 1.445kg.The ratio was close to 25:1,which was similar to the carbon-nitrogen ratio of the stack X₃,and was consistent with the evaluation result of the grey correlation method,indicating that the optimization result was the best carbon-nitrogen ratio.In the single factor test,by changing the type of bacterial agent,the ventilation mode and amount,the amount of salt oil,and analyzing the temperature and other indicators,it can be concluded that working condition 3 was the best bacterial agent,working condition 3 was the best ventilation mode,working condition 1 was the optimum ventilation rate,working condition 4 is the optimum salt content,and working condition 1 is the optimum oil content.The optimal processes obtained by the response surface methodology were bacterial agent 2,ventilation mode 3,ventilation volume900L,salt content 1%,and oil content 4%.The two groups did the verification test,and the results were basically consistent with the predicted value.After calculation,the carbon emission of municipal sludge aerobic compost and land use was 731.733kg/t dry matter,and the carbon emission of kitchen waste aerobic compost and land use was 429.297kg/t dry matter,the carbon emission of synergistic aerobic compost and land use was 578.015kg/t dry matter.It provided reference for carbon emission reduction of municipal sludge and kitchen waste industry.In this study,by examining the effects of the optimal carbon-nitrogen ratio and other factors on the composting effect,the optimal composting parameters of municipal sludge and kitchen waste were determined,and the carbon emissions were calculated at the same time,It had reference value for carbon neutralization and carbon peak.On the basis of reduction,harmlessness and resource utilization,a coordinated aerobic composting process for municipal sludge,kitchen waste and agricultural and forestry waste was established.