Nitrogen removal efficiencies and microbial communities in full-scale IFAS and MBBR municipal wastewater treatment plants at high COD:N ratio

摘要

The relative locations of AOB,NOB,and DNB were examined for three different kinds of carriers in two types of hybrid bioflm process configurations:integrated fixed-film activated sludge(IFAS)and moving bed bioflm reactor(MBBR)processes.IFAS water resource recovery facilities(WRRFs)used Anodkainess^TM K1 carriers(KC)at Broomfield,Colorado,USA and polypropylene resin crriers(R)at Fukuok,Japa,whic MBBR WRFS used KC crier at South Adams Couty,Colorado,USA and sponge carriers(SC)at Saga,Japan.Influent COD to N ratios ranged from 8:1 to 15:1.The COD and BOD removal efficiencies were high(96%-98%);NH^+4-N and TN removal efficiencies were more varied at 72%98%and 64%-77%,respectively.The extent of TN removal was higher at high SRT,high COD:N ratio and low DO concentration in the anoxic tank.In IFAS,RC with high specific surface area.(SSA)maintained higher AOB population than KC.Sponge carriers with high SSA maintained higher overall bacteria population than KC in MBBR systems.However,the DNB were not more abundant in high SSA crriers.The diversity of AOB,NOB,and DNB was fairly similar in different carriers.Nitrosomonas sp.dominated over Nitrosospira sp.while denitrifying bacteria included Rhodobacter sp.,Sulfuritalea sp.,.Rubrivivax sp:Paracoccus sp..and Pseudomonas sp.The results from this work suggest that high SRT,high.COD:N ratio,low DO concentration in anoxic tanks,and carriers with greater surface area may be recommended for high COD,BOD and TN removal in WRRFs with IFAS and MBBR systerms.