The Mbr Process High-salt Wastewater Pilot Study

The experimental study was about the biological treatment of wastewater containing salt by MBR process.This dissertation was mainly studied the effects of MBR process on organic matter and ammonia nitrogen degradation in high salinity wastewater at normal temperature(18～25℃),studying the influence of the prformance of activated sludge and the organic matter and ammonia nitrogen degradation by changing the salinity,and exploring the feasibility of realizing short - cut nitrification steadily on MBR process. These researches were promotive to the biological treatment of high saline wastewater.The experiment studied the influence of the organic matter and ammonia nitrogen degradation on DO,HRT,pH and MLSS when seawater percentage was 50%,COD was 700～800mg/L and NH₃-N was 80～100mg/L.Results showed that the COD and ammonia nitrogen degradation was lower when DO in the aerobic area was less than 1mg/L.But,because of the identity of the MBR,the degradation of COD was better than the degradation of ammonia nitrogen.It could obtain a better removal efficiency when DO in the in the aerobic area was 1～2mg/L.The COD and ammonia nitrogen degradation was 91.91%and 91.44%respectively.The COD and ammonia nitrogen degradation increased with the extension of HRT.It could obtain a better removal efficiency,91.34%and 91.64%respectively when HRT was 12h.COD degradation was 91.82%when pH was 8.0.Ammonia nitrogen degradation could achieve 93.69%because of the the strongest activity of nitrosation bacteria in the reactor when pH was 8.5.But the degradation could be affected because of the inhibition of microbial activity when pH was more than 9.COD and ammonia nitrogen degradation was 92.01%and 91.94% respectively when MLSS was 7～8g/L.Too high or too low MLSS will affect the degradation.Microbial activity was inhibited largely because of the affection of salinity.So,COD and ammonia nitrogen degradation of the experiment was lower than processing fresh wastewater at the same DO,and,only when HRT was longer and MLSS was larger than processing fresh wastewater,could it obtain a better degradation.The experiment studied the influence of the performance of activated sludge and the COD and ammonia nitrogen degradation on changes in salinity,and,the cycle of degradation was back to the stable after affected on changes in salinity when DO in the aerobic area was 2～3mg/L,HRT was 12h,pH was 7.5～8.5,MLSS was 7～8g/L,COD was 700～800mg/L and NH₃-N was 80～100mg/L.Results showed that higher salinity was conducive to improve settlement performance of activated sludge.SVI was 105 and 70 respectively when the seawater's salinity was 10%and 50%.The impact of biological treatment was not obvious when the seawater's salinity changed within the scope of 30%, but,the impact of biological treatment was more obvious when reducing the salinity of seawater than increasing it.The COD and ammonia nitrogen degradation reduced from 91.73%and 91.03%respectively to 81.98%and 74.30%respectively when the salinity of seawater reduced from 50%to 30%,and the cycle of degradation backing to the stable needed 4 weeks to 5 weeks.The COD and ammonia nitrogen degradation reduced from 93.82%and 92.11%respectively to 86.90%and 83.05%respectively when the salinity of seawater increased from 30%to 50%,and the cycle of degradation backing to the stable only needed 2.5 weeks.The experiment studied the influence of nitrite accumulation on DO,ammonia nitrogen and pH when seawater percentage was 50%,HRT was 12h,MLSS was 7～8g/L,COD was 700～800mg/L and NH₃-N was 80～100mg/L.Results showed that nitrosation rate could be achieved more than 50%when DO was 0.5mg/L～1mg/L,pH was 8.5～9 and NH3-N was 225mg/L.Nitrification could be achieved.But the nitrosation rate would decline with the extension of reaction time because the adaptability of nitrobacteria.