Research On Construction And Operation Characteristics For Waste Disposal System Of Rural Toilet

In view of the problem of poor recycling effect of feces in rural toilets,this study constructed a new rural toilet sewage and feces treatment system based on the summary and analysis of the existing toilet feces treatment technologies,and designed a multi-stage biological contact-ecological filter and manure multi-chamber composting process.The operation characteristics of toilet sewage multi-stage biological contact-ecological filter and manure multi-chamber composting reactor were investigated,and the relevant mechanism was discussed.The results can provide basis for the development and application of rural toilet sewage treatment and manure composting technology.Based on the characteristics of scattered discharged and large fluctuation in quantity and quality of toilet sewage,a multi-stage biological contact ecological filter treatment technology for toilet flushing sewage was developed,a 3t/d multi-stage biological contact-ecological filter wastewater treatment reactor with pilot-scale was established.The start-up and stable operation characteristics of sewage treatment reactor were studied.The results showed that at the end of the start-up period(31d),the removal rates of COD and ammonia nitrogen in the effluent of the multi-stage biological contact tank unit can reach 95.54%and 82.73%respectively.indicating that the multi-stage biological contact process can quickly adapt to toilet sewage and start successfully within 31d.In the stable operation period,the removal rates of COD,TN and TP in the influent of the reactor can reach more than 90%,80%and 95%,which can realize the efficient removal of pollutants from toilet flushing sewage,and the effluent can meet the discharge standard.Based on microbial high-throughput sequencing technology,the microbial community characteristics of sewage treatment reactor in stable operation period were studied.The results showed that the abundance of main microbial species in each process unit of sewage treatment reactor changed little.At the bacterial genus level,Thiotrix and Bacteroidetes were the main dominant bacterial microorganisms;At the Archaea level,Methanosaeta,Methanosarcina and Methanobrevibacter were the main dominant microorganisms.The economic analysis of the reactor showed that the investment cost was about 15000 yuan/m~3and the direct operation cost was 0.99 yuan/m~3.In view of the low efficiency of material mixing and composting in the existing fecal composting technology,integrating the advantages of uniform material mixing of horizontal composting reactor and zoning of tower composting reactor.A new multi cell composting reactor was constructed.Using the discrete element method,the discrete element simulation model of multi cell fecal composting reactor was established to study the particle flow state and material mixing effect of the reactor.The results showed that the transport velocity of feces in each cell of the reactor decreases gradually,and the particle velocity in the side wall area was greater than that at the axis.The movement state of material particles added at different time was roughly the same,and the sequence of material addition had no significant effect on the mixing effect of materials.Taking rural toilet manure as the object,a pilot-scale multi-chamber composting reactor was established,and its performancein 60 dayscontinuous operation was studied.The temperature order of each cell in the reactor was cell B,cell A and cell C,and the overall temperature in stage I was the highest.The moisture content of each cell was positively correlated with the moisture content of raw materials,and each stage shows good air permeability.At the same time,the porosity and bulk density of the stockpile in stage I were the best,and the volume and weight reduction effect in stage III was the best,indicating a good composting effect.The analysis results of residence time distribution characteristics of fecal materials in different stages showed that the total average residence time of reactor materials was 12～14 days,and the materials between cells showed a good feeding state.The indexes of compost products treated by the reactor can meet the agricultural standards.The results can provide reference for the design and sustainable applicationof rural toilet system.