Study On The Treatment Of High Ammonia Nitrogen Chemical Wastewater By Functional Bacteria Enhanced Biofilm Combination Process

With the rapid development of my country's economy,the industrialization process is also accelerating,in which chemical plants plays a huge role.However,human have gradually discovered that while chemical plants bring huge benefits,they also bring a huge pollution load.There are many kinds of chemical wastewater with complex components,unstable water quality and most of them contain refractory organics,heavy metals and other toxic and harmful pollutants.How to treat such wastewater efficiently and at low cost has always been the focus of the industry.The main treatment process for high ammonia nitrogen chemical wastewater at home and abroad is the combined physicochemical method+biological method.At present,the biochemical treatment unit of high ammonia nitrogen chemical wastewater mainly uses a multi-stage biological contact oxidation(BCO)tank to ensure the stable removal of nitrification.The nitrification efficiency is low,the denitrification effect is poor,and the back-end BCO pool is often idle in actual operation.Therefore,it is imperative to propose a technical transformation plan for the problems existing in this type of treatment process and form a new efficient and economical biological treatment unit.In this study,the high biodegradable high ammonia nitrogen industrial wastewater after physicochemical pretreatment of a chemical factory in Hebei was taken as the research object,and the tolerance performance of a super anti-stress bacterial agent HN-AD compound bacteria independently screened by the research group was used as the research object.Strong and efficient simultaneous denitrification and other characteristics,with the help of bacterial agent hanging film technology,a combined process of two-stage biological contact oxidation tank+moving bed biofilm reactor(two-stage BCO+MBBR)is constructed.The method of increasing the ammonia nitrogen concentration by gradient is adopted,and the two-stage BCO tank pretreatment system is activated by the sludge film formation of the sequence batch influent.Nearly 100%removal of NH₄⁺-N and partial removal of COD and TN are achieved at the front end with the help of the two-stage BCO system;the MBBR system activated by the HN-AD compound bacterial agent hanging film performs advanced treatment on the effluent of the two-stage BCO pool to achieve the most of the removal of COD and TN in an aerobic environment will eventually meet the emission requirements.And with the help of high-throughput sequencing methods,the two-stage BCO and MBBR reactors were started to form membranes,and the changing trends of pollutants and the microbial community structure in the process of parameter optimization were studied,and the effect of the combined process on the treatment of real high-ammonia nitrogen chemical wastewater was investigated.condition.The main conclusions are as follows:(1)The start-up periods of the first-level BCO tank and the second-level BCO film formation were 37 days and 39 days,respectively.The ammonia nitrogen removal rates of the two tanks with different ammonia nitrogen concentration gradients were both higher than 98%.The start-up cycle of MBBR bacterial agent hanging film took 17 days.After the film hanging was completed,a layer of light yellow biofilm was formed on the surface of the filler.The 24h effluent COD and TN concentrations of the system were 12.3 and 0.3mg/L,respectively.(2)The optimal HRT and the optimal influent C/N ratio of the two-stage BCO pretreatment system were determined to be 24h and 6,repectively.After the optimization,the COD,NH₄⁺-N and TN concentrations of the two-stage BCO effluent are 93.31,4.15and 86.13 mg/L.The results of high-throughput sequencing showed that the HN-AD bacteria dominated by Thauera and Nirosomonas play a major role in the denitrification process of the two-stage BCO system.(3)The optimal HRT and the optimal influent C/N ratio of MBBR advanced treatment system were determined to be 9h and 4,repectively.After the parameter optimization,the MBBR effluent COD and TN concentrations are 2.98 and 14.96 mg/L,respectively.Thauera bacteria are play a major role in the process of system denitrification.By comparing the gene composition analysis of denitrification function in the system under different C/N ratio conditions,it can be seen that with the increase of C/N ratio,the abundance of the related genes(nap A,nap B,nir S,nor B,nor C,nos Z)which are play the main denitrification function showed a gradual upward trend.When C/N?4,several denitrification genes maintained a high proportion,and low C/N ratio was not conducive to the expression of denitrification genes.(4)After the high ammonia nitrogen chemical wastewater is treated by the two-stage BCO+MBBR combined process,the effluent meets the first-level A standard discharge of"Pollutant Discharge Standards for Urban Sewage Treatment Plants",and the effluent NH₄⁺-N<5mg/L,COD<50mg/L,TN<15mg/L.The combined process has a good treatment effect,and the effluent is much higher than the chemical park management standard.Compared with the on-site wastewater treatment cost,the cost per ton of water is reduced by 25 to 30 yuan.