The Influence Of Pilot Two-stage MBBR On Advanced Nitrogen Removal Of Reverse Osmosis Concentrate

Moving bed biofilm reactor(MBBR)has strong impact resistance load capacity and good denitrification effect.A pilot nitrosation/nitrification-denitrification two-stage moving bed bio-film reactor(MBBR)was developed for the advanced nitrogen removal of high NH4+-N(TN)reverse osmosis concentrate from the low pressure reverse osmosis unit,which was produced from the high-quality water reclaimation of municipal wastewater.And Filling Ratio(FR),Dissolved oxygen(DO),C/N ratio,carbon source type and hydraulic retraction time(HRT)were investigated on the effect of MBBR operation.The main conclusions were as follows:Under the conditions of PE carrier,8HRT of nitrosation/nitrification MBBR,12 HRT of denitrification MBBR,methanol carbon source,DO less than 1.0mg/L,the effects of 51%,42% and 32%FR on the two-stage MBBR were investigated.The results showed that the removal rate of NH4+-N slightly increased with the decrease of FR in the nitrosation MBBR,when FR was 32%,the removal rate of NH4+-N was optimal(73.2 ± 6.1%).And the removal rate of NH4+-N slightly decreased with the decrease of FR in the denitrification MBBR.Taking account of economical availability,the results showed that FR32% was the best,and the removal rate of NO3--N was 64.9 ± 10.4%.Under the conditions of PE carrier,8HRT of nitrosation/nitrification MBBR,12 HRT of denitrification MBBR,methanol carbon source,the effects of 1.14mg/L,0.87mg/L and 0.67mg/L DO on nitrosation/nitrification MBBR were investigated.The results showed that NH4+-N removal rate decreased with the decrease of DO,1.14 mg/LDO was optimal for nitrosation MBBR.The effects of 4.5,5.6 and 6.8 C/N on denitrification MBBR were investigated.The results showed that the removal of NO3--N increased with the increase of C/N ratio,Taking account of economical availability,the optimal C/N was 4.5 for denitrification MBBR.Under the conditions of PE carrier,12 HRT of denitrification MBBR,methanol and sodium acetate were campared as external carbon source influenced on the nitrification MBBR.The results showed that methanol was the best carbon source for DFRO concentration of de nitrifi-cation MBBR,and the removal rate of NO3--N was 50.3 ± 13.1 %.Under the conditions of PE carrier,0.87mg/LDO,methanol carbon source,The effects of 4h,8h and 12 h HRT on nitrosation/nitrification MBBR were investigated.The results showed that:the removal rate of NH4+-N decreased with the increase of HRT,and the best HRT was 4h,the removal rate of NH4+-N was 74.1±12.9%.The effects of 6h,12 h and 18 h HRT on denitrification MBBR were investigated.The results showed that:the best HRT of denitrification MBBR was 12 h,and the removal rate of NO3--N was 63.2 ± 9.0%.Considering the influence of denitrification and economy of secondary MBBR system,the optimal operating conditions of secondary MBBR for DFRO concentrate were 32% FR,1.14mg/LDO and 4h HRT in nitrosation/ nitrification reactor;32% FR,6.8 C/N ratio,methanol as carbon source and 12 h HRT in denitrification reactor.