Study On The Treatment Characteristics Of Urine By Combination Of Activated Sludge Process And Membrane Process

In recent years,the country has vigorously promoted the"toilet revolution"in rural areas and transformed old toilets to improve the rural environment,revitalize the rural economy,and improve the people's living standards.However,for some water-scarce areas and remote areas,the lack of water resources,the difficulty of laying the pipe network,and the problems of toilet sewage treatment make traditional water flush toilets unsuitable for construction and use in this area.The source separation ecological toilet can effectively solve the above problems,but the problems of urine disposal and reuse have become an important factor restricting its promotion.To this end,this paper proposes a combination of activated sludge and membrane technology,constructs the SBR-MF-UF-RO urine treatment system,removes a large amount of organic matter in urine through the bioreactor in system,and uses membrane technology to further deepen the urine to meet the requirements of reusing toilet after urine treatment.When using the SBR reactor to process urine,the high concentration of ammonia nitrogen produced by urea hydrolysis and the accumulation of salt in the reactor were important factors affecting its stable operation.To this end,the effects of sludge concentration,aeration time,salinity and pH on the nitrification performance of the reactor were studied.Finally,the concentration of sludge in the reactor was adjusted to12000 mg/L,and the p H was maintained at 7.0?8.0 to achieve complete removal of ammonia nitrogen.The method of gradually increasing the salinity was used to domesticate the sludge.The urea and ammonia nitrogen could be completely removed during the domestication stage,the COD concentration of the effluent was stable,the sedimentation of the sludge was gradually enhanced,and the salt tolerance was improved.In order to further improve the efficiency and capacity of the SBR reactor to process urine,the effects of carbon source,water intake method and volume load on its reaction were studied.The results showed that when the mixed carbon source of glucose/sodium acetate with a mass ratio of 0.73:1 was added,the nitrification and denitrification rates of the reactor were the fastest,and the nitrous nitrogen concentration in the effluent was relatively low.Compared with the single-stage inflow mode,the two-stage inflow mode had significantly improved the nitrogen removal effect of the reactor,and the nitrate nitrogen and nitrous nitrogen concentrations in the effluent had been significantly reduced.The maximum volume of urine treated in a single cycle of the SBR reactor was 875mL,and the volume load of urea at this time was 0.97 kg/(m~3·d).The MF-UF system was used to treat the SBR reactor effluent,and the SDI was reduced to 1.3?2.5,which met the RO system influent requirements.According to the changes of the desalination rate,normalized water permeability and membrane pressure loss under different recovery rates,the optimal recovery rate of the RO system was determined to be 50%.At this recovery rate,the RO system has an excellent removal effect on total nitrogen,COD,and salinity in the incoming water.After the urine was treated by the SBR-MF-UF-RO system,the quality of the produced water met the toilet flushing standards.Based on the above test results,the activated sludge method and membrane combination process are used to treat urine,which solves the problem that the urine in the source separation toilet is difficult to treat and reuse.The development of separate toilets provides new technical support,and also provides a new direction for the promotion of the"toilet revolution"in water-scarce areas and remote areas.