Influence Of Material Mixing And Temperature Strategies On The Efficiency Of Multi-source Organic Solid Waste Aerobic Composting

With the development of traditional Chinese medicine industry,the disposal of traditional Chinese medicine residues has become a serious problem.Synergistic composting of traditional Chinese medicine residues,biogas residues and municipal sludge can realize simultaneous centralized treatment of various organic solid wastes,greatly reducing the construction and operation costs of treatment facilities.This paper uses biogas residues,municipal sludge and traditional Chinese medicine residues as raw materials to carry out collaborative composting experiments to explore the effects of raw material ratio and temperature control on the efficiency of multi-source organic solid waste collaborative composting process.The experiment first took the lignin content as an indicator,and set up four experimental groups with lignin content of 7.5%,10%,12.5% and 15% to carry out research on the ratio of synergistic composting raw materials.At the end of composting,the organic matter degradation rates of each group were 12.07%,16.88%,15.57% and9.16%,respectively,and the organic matter degradation rates were higher in the experimental groups with lignin content of 10% and 12.5%;The degree of humus(HS)increased by 18.22 mg/g and 20.10 mg/g,respectively,and the humic acid(HA)content increased by 23.54 mg/g and 26.39 mg/g,respectively.This is because the lignin content is 10% and 12.5% experimental groups contained adequate amount of lignin and sufficient biogas residue to provide easily degradable organic matter.The increase of lignin content in the raw material increased the relative abundance of Actinobacteria.Therefore,the lignin content in the compost raw material is 10%-12.5%,and the mass percentage of the biogas residue in the compost is 40%-59% to provide sufficient easily degradable organic matter,so that the synergistic composting effect is the best.In addition,based on the optimal mixing ratio of biogas residue,traditional Chinese medicine residue and municipal sludge,this paper studies the effect of temperature regulation on the composting effect in the process of multi-source organic solid waste synergistic aerobic composting.Three experimental groups were set up in the experiment.After the composting started,the temperature of the compost was controlled at 60℃ with a water bath for 1d,3d and 5d respectively(hereinafter referred to as 60℃1d,60℃3d and60℃5d groups).The results showed that the three temperature controls maintained the high temperature period for 8d,10 d and 12 d respectively,and the organic matter degradation rates of each experimental group were 15.3%,15.8% and 17.6%,respectively.Colony diversity analysis showed that after continuous high temperature control,the abundance of thermophilic microorganisms such as Bacillus,Thermoactinomyces and Planifilum was increased,which accelerated the degradation of organic matter and the production of humus,and improved the quality of compost.The grey relational analysis method was used to evaluate the quality of the three experimental compost products.It was found that the correlation degree between the "60℃5d" group and the "completely decomposed" standard parameter reached 0.81,indicating that the "60℃5d" experimental group had the best degree of decomposing.At the end of this paper,the passivation process and law of heavy metals in the compost in the process of multi-source organic solid waste aerobic composting are also studied.The experiment took the heavy metal cadmium(Cd)as the research object,and used 1.5% calcium magnesium phosphate fertilizer + 1.5% zeolite as the passivation agent.Add passivating agent in the heating period(0d),high temperature period(3d)and cooling period(13d)of compost respectively to study the effect of passivation agent on the passivation effect of heavy metal Cd with different dosing time.At the end of composting,the proportion of residual Cd in each experimental group increased by 42%,39%,and32%,respectively,while the weak acid-extracted Cd decreased by 44%,40%,and 33%,respectively;the humus in each group increased by 25.24 mg/g,16.09mg/g,and13.92mg/g,respectively.indicating that the passivation agent was added at the early stage of composting,and it performed the best in both heavy metal passivation and compost decomposing.