Optimizing nitrogen removal in PN/A process:Step-Feed influence analysis
In this work,a novel model was established to optimize the C/N in the aerobic section based on the regulation of the influent distribution ratio of each aerobic section,using pre-decarbonized wastewater and municipal wastewater as target wastewater.This work was aiming at achieving the stable operation of the partial nitrification-anammox(PN/A)process under realistic conditions.Four groups of sequential batch reactors(SBR)with the same specifications run in oxic/anoxic/oxic/anoxic(O/A/O/A)mode,R1,R2,R3,and R4 operated in the step-feed mode with the influent distribution ratios(pre-decarbonized wastewater:municipal wastewater)of 1:0,2:1,1:1,and 1:2.The results illustrated that R1failed to realize the PN/A process and total nitrogen removal efficiency(NRE)was only 60.2%.Along with the decreasing influent distribution ratio,R2,R3,and R4 completed the PN/A process on the 34th,30th,and 36th days,which NRE reaching 71.8%,80.3%,and 74.1%.Among them,R3 had the optimized performance with best stability,and the contribution of anammox reaching 83.9%.It was revealed that sludge exhibited excellent settling characteristics and optimal particle size.Moreover,high-throughput data also demonstrated the abundance of ammonia-oxidizing bacteria(Nitrosomonas)and anammox bacteria(Candidatus_Kuenenia)at 2.74%and 12.17%.These microbial populations synergized effectively with aerobic heterotrophic bacteria(AHB).Hence,the step-feed model could be conductive to achieve a stable PN/A process.The influent distribution ratio of 1:1was suggested as a suitable reference value,fostering better enrichment and balance of functional microorganisms.
step-feedPN/A processinfluent distribution ratiocompetitive inhibition
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