Study Of The Effectiveness Of ABR-CSTR Integrated Reactor For Removal Of Carbon And Nitrogen

Anaerobic baffled reactor?ABR?is a highly efficient anaerobic reactor based on the theoretical basis of multi-stage anaerobic reactor,which has the advantages of simple structure,strong retention of sludge and high stability.At the same time,the system of aerobic nitrosifying granules can achieve high efficiency and stable shortcut nitrification,which laying a foundation for the new biological nitrogen removal technology.Above all,this study carried out a research of ABR-CSTR integrated reactor for removal of carbon and nitrogen.CSTR used the granular sludge system with excellent performance of retention and enrichment of,then the granular sludge was cultured to aerobic nitrosifying granules;on the basis of the above,the effluent was flow back to the front compartment of ABR in order to remove the nitrogen with the high quality carbon source produced by hydrolysis acidification.Finally,the integrated reactor achieved the separation of the hydrolysis acid and methane production,the short cut nitrification and denitrification,and also achieved the high removal efficiency of carbon and nitrogen.The main content and conclusions are as follows:?1?Gradually decreasing HRT in sedimentation tank from 2 h to 0.75 h and increasing organic loading rate from 1.5 kg·?m³·d?^-1 to 2.0 kg·?m³·d?^-1 while C/N in aerobic zone was controlled as 2.While the system operated 110 days,the mature granular sludge in aerobic zone presented compact structure,excellent sedimentation performance and slight yellow color.And then the C/N rate was decreased from 1 to0.4 and the ammonia nitrogen volumetric loading rate was increased from0.89 kg·?m³·d?^-1 to 2.23 kg·?m³·d?^-1.When the system operated for another 45 days,the mature nitrosation granular sludge in aerobic zone present compact structure and yellow color while the nitrite accumulation rate was about 80% in effluent.?2?While the HRT were 15h and 10h,the OLR were 1 and 2 kg·?m³·d?^-1respectively,the effluent COD concentration of ABR-CSTR integration reactor was less than 30 mg·L^-1,the COD removal rate was high and maintained at 95%.The whole COD removal rate has little effected while Changing the reflux ratio?R=100,150,200,250%?.When HRT=5 h,OLR=3 kg·?m³·d?^-1 and changing reflux ratio will cause anaerobic COD removal rate to be fluctuated but the whole removal rate remained above 90%.?3?While the HRT were 15h and 10h,the OLR were 1 and 2 kg·?m³·d?^-1respectively,the NH₄⁺-N removal rate of ABR-CSTR integration reactor was high?more than 90%?,the effluent NH₄⁺-N concentration was within 8 mg·L^-1,increasing the reflux ratio can slightly enhance the removal rate of NH₄⁺-N.When HRT was shortened to 5 h and the OLR increased to 3 kg·?m³·d?^-1,the NH₄⁺-N removal rate dropped to below 70%,added the reflux ratio would make the removal rate has the trend of the further deterioration.In addition,although the addition of the reflux rate could increase the NH₄⁺-N removal rate,but the accumulation rate of influent nitrite nitrogen was decreased,which caused by the lower FA concentration.?4?When the reflux rate was at the same value,the TN removal rate increased first and then decreased with the increasing of the OLR.When HRT=10h,OLR=2kg·?m³·d?^-1 and R=200%,the system achieved the highest TN removal rate?about80%?in this research,the concentration of TN was within 20 mg·L^-1.At the same time,NH₄⁺-N removal rate was much higher,which ensured the successful progress of denitrification and nitrification reaction.And it also happened to be the optimal conditions of carbon-removal.So,the condition above was the optimal operating conditions of removal of carbon and nitrogen in this paper.?5?The COD removal rate of anaerobic part was as high as 90%,large quantities of organic matter were removed as the carbon source of denitrification.The aerobic part had the process of further degradation of COD.Eventually the whole COD removal rate was more than 95%.The TN removal rate of anaerobic part closed to70%,the denitrification effect was obvious.There were some ANAMMOX nitrogen removal processes in the back-end compartment of ABR.The TN removal rate of aerobic part increased because of the simultaneous nitrification and denitrification?SND?phenomenon,so as to strengthen the system capacity of nitrogen-removal,and TN removal rate ultimately achieved about 80%.