Optimization Of Biochemical Treatment Process For Tail Water Of The Biological Processor For Kitchen Waste

Treating kitchen waste by using kitchen waste biological processor to approach kitchen waste has been widely used in many cities in our country.However,tail water generated in this treatment process needs purification and treatment before it can be discharged.In this paper,according to the characteristics of high concentration of organic matter and suspended matter in the tail water of kitchen waste biological treatment machine,by constructing the mechanical stirring anaerobic bioreactor(MAAB)-moving bed membrane bioreactor(MBMBR)pilot device,the treatment efficiency of simulated tail water under different parameters was investigated.The main research results are as follows:The anaerobic phase was treated with MAAB.The treatment efficiency of MAAB on simulated tailwater was investigated from the aspects of treatment effect,stability and microbial metagomics.The main process parameters,such as hydraulic retention time(HRT)and organic load(OLR),were selected.HRT of 1 d and OLR of 12.5 g COD/(L·d)are the optimal process parameters of MAAB reactor.Under this condition,MAAB influent concentration is 12500mg/L,MAAB effluent average COD concentration is 1727 mg/L,and average COD removal rate is 86.2%.For the MAAB reactor used in this experiment,the hydraulic retention time is the more critical process parameter.The key enzymes and metabolic pathways of methanogenesis of anaerobic granular sludge in the stable operation stage of MAAB reactor were investigated by metagenic analysis,and the differences between them and microbial diversity of anaerobic granular sludge in the acidizing instability stage were investigated.In the unstable stage of reactor acidification,microbial diversity decreased obviously,bacterial species and quantity decreased greatly.In the optimization study of aerobic treatment of anaerobic effluent,the treatment efficiency of MBMBR was investigated,and the control parameters of dissolved oxygen concentration in MBMBR reactor were optimized to improve the nitrogen removal effect.When the concentration of dissolved oxygen in the MBMBR reactor decreased to 1.06 mg/L,the average removal rate of total nitrogen increased to 83.5% and the average concentration of total nitrogen in the effluent was31.2 mg/L.At this stage,the average concentration of COD in the inlet and effluent of the MBMBR reactor is 1727 mg/L and 136 mg/L respectively,and the removal rate reaches 92%.The reduction of dissolved oxygen concentration will not affect the removal of COD in the MBMBR reactor.Metagenomics analysis was used to investigate the differences of microbial diversity and the changes of nitrogen metabolic pathways in MBMBR reactors with different concentrations of dissolved oxygen.The concentration of dissolved oxygen between 1 mg/L and 1.5 mg/L does not have a negative effect on the nitrification metabolism of sludge in the reactor,and the denitrification effect is better,and the removal effect of TN is better.The optimized parameters of the MAAB-MBMBR treatment process obtained in this paper can be used to efficiently purify the simulated tail water of the biological processor of kitchen waste.The treated effluent not only meets the requirements of the management discharge in the Quality Standard for Sewage Discharge into Urban Sewers(GB/T 31962-2015).It can also be used as the rinsing water of the biological processor of kitchen waste for reuse.This paper provides experimental basis and data support for the development and application of the biological clean treatment technology of the tail water of the biological treatment machine of kitchen waste.