Study On Shortcut Nitrification And Denitrification For Catalyst Production Wastewater Treatment In Sequencing Batch Reactor

Petroleum industry is our country’s fundamental industry. Petroleum refining as thedeep processing treatment of raw oil is closely related to the basic necessities in ourdaily life. Production process of cracking catalyst in refinery uses various substanceswhich are rich of nitrogen, such as ammonium salt and ammonia, producing a largeamount of high ammonia and suspended solids wastewater. It is an urgent issue forcatalyst manufacturing enterprise to remove ammonia from the wastewater in aneconomic and effective way. Comparing with the traditional biological nitrogen removalprocess, shortcut nitrification-denitrification has a lot of advantages, since it can reduceenergy and alkalinity consumption in nitrification stage and cut down carbon sourceaddition in denitrification stage. Through the shortcut nitrification and denitrificationbiological nitrogen removal treatment of catalyst wastewater in sequencing batchreactor, it studied effects and stabilities of SBR running condition at differenttemperature, dissolved oxygen (DO), sludge retention time (SRT). Combined with thevariation curves of pH value and oxidation-reduction potential (ORP) in biologicalnitrogen removal process, it provides a real-time control method, and established thekinetics of shortcut nitrification according to the change of ammonia concentration.Results showed that it could realize sludge acclimation from complete nitrificationinto shortcut nitrification in a relatively short period under condition of35℃, DO1mg/L. Nitrite accumulation rate was more than90%.There was no obvious impact on performance of ammonia removal when changingrunning temperature. Average ammonia removal rate and nitrite accumulation rateremained larger than80%,90%respectively. In the temperature of33℃,28℃,30℃,the ammonia removal volume load was0.2~0.3kgNH3-N/(m3d) and showed no greatervolatility.Change of DO was significant to the ammonia removal volume load. The ammoniaremlval volume load was0.2~0.3kgNH3-N/(m3d) at DO1mg/L, and it could reach0.45kgNH3-N/(m3d) when DO was1.5mg/L. As the influent was actual catalystwastewater, there was a huge fluctuation on influent ammonia concentration. So thereshould be real-time control on the nitrification reaction time combined with thevatiation of pH value and ORP in the process. If influent ammonia was too high, thefixed aeration time was7h. Ammonia removal rate and nitrite accumulation rate werelarger than90%and didn’t change so much at different DO. Even when the DO was1.5mg/L, the nitrite accumulation rate also stayed above90%steadly.Change of SRT had no obvious effects on ammonia removal rate and nitrite accumulation rate. The average ammonia removal rate and nitrite accumulation were79.47%,82.58%and98.94%,98.2%at SRT20d,40d. The sludge concentration couldstay at a higher level when SRT was40d.Finally, it worked out the kinetic equation in nitrification stage through the kineticanalysis of shortcut nitrification and denitrification in the treatment of catalystwastewater.