Optimization And Operation Control Research On PNP/ANAMMOX Denitrification Process

In recent years,the contradiction of relatively backward sewage treatment process and increasingly stringent Total Nitrogen(TN)control standards has become prominent,so it is imperative to positively look for a more efficient biological nitrogen removal process to control the water nitrogen pollution.Anaerobic ammonia oxidation(Anammox)is one of the most direct and economical biological nitrogen removal pathway,but classic processes based on Anammox still exist some problems such as not high enough of TN removal rate and so on.Therefore,on the basis of summarizing the problems existing in the pilot-scale synthetic leather wastewater treatment,this study focuses on improving and optimizing the process in a lab-scale type,so as to develop a new and efficient biological nitrogen removal process,which is based on Partial Nitrification Process(PNP),Anammox and sulfur autotrophic denitrification,for removing nitrogen economically and efficiently and ensuring effluent quality meets the standard.The two-stage PNP-Anammox treatment system,including a SBR reactor with the effective volume of 1 m3 as PNP main reactor and a UASB reactor with the effective volume of 0.39 m3 as Amammox main reactor,is adopted to research the treatment of actual synthetic leather wastewater.The TN removal rate stabilizes over 80%and TN volume load removal rate(NRR)is up to 0.54 kgN/(m3·d)in the half-nitrosofication joint Anammox operation mode.However,the effluent TN still could not meet the discharge standard,and the coordination between the two stage processes is difficult.Besides the operation of joint process is complex,and the Ammmox reactor is easily inhibited by high-concentration NO2--N.The integrated PNP-Anammox process can be achieved successfully by inoculated mixed AOB(Nitrosification bacteria)and AnAOB(Anammox bacteria)sludge with 3:5 in a lab-scale SBR reactor with an effective volume of 4 L in the condition of DO?0.1?0.3 mg/L and pH?7.4?8.5.The removal rate of TN and total nitrogen volume load could be up to about 90%and 0.21 kgN/(m-d)respectively,when treating the simulated wastewater which contains 600?800 mg/L NH4+-N,200 mg/L COD.After about a month of domestication,a new integrated PNAD process which couples sulfur-based autotrophic denitrification with integrated PNP-Anammox autotrophic denitrification process,has been developed by adding elementary substance S to the system.When this new system is adopted to treat the raw simulated water containing 800?900 mg/L NH4+-N and no organic carbon,the effluent TN always keeps stable at 5 mg/L or less and the removal rate of TN and NRR is up to about 98%and 0.23 kgN/(m3·d)respectively.TN removal rate keeps steady at about 98%in 20d continuous operation,and NRR is about 0.12 kgN/(m-d)with synthetic leather wastewater as influent of PNAD.Through batch experiments,the related biochemical reactions about biological denitrification in PNAD process are indicated,each sequence of biochemical reactions and its contribution to the TN removal rate are analyzed,and the flora composition and structure in different periods of process operation is identified.A preliminary inquiry on PNAD process mechanism is achieved.In short,the major problems of two stage PNP-Anammox process in synthetic leather wastewater treatment such as not high enough of total nitrogen removal rate and so on,could be solved through the PNAD technology research and development,and the effluent quality can achieve the emission standard.