The Impact Of Activated Carbon On Application Of MBR In Marine Aquaculture Wastewater Treatment

With the rapid development of marine aquaculture industry,the amount of wastewater discharged is increasing and the water environment in the coastal areas is seriously deteriorated.In order to protect the marine environment and reduce the spread of disease,the treatment of intensive aquaculture wastewater has become an inevitable trend in the development of marine aquaculture industry.Membrane bioreactor is a combination of biological wastewater treatment technology and membrane separation technology,which regarded as a new technology of wastewater treatment and reused technology,with high efficiency of contaminant removal,less the amount of excess sludge and water quality and stability,etc.which has been applied in traditional domestic sewage,industrial wastewater,livestock wastewater treatment and other fields.However,this method also had some shortcomings,the most prominent was that the membrane pore was easy to plug or formed a filter cake layer under the long-term effect,resulting a large decline in membrane flux,the increasing of cleaning costs and seriously influenced MBR wastewater treatment effect.In order to solve these problems,it could improve the characteristics of activated sludge by adding powdered activated carbon（PAC）,which could reduce the membrane fouling and prolong the life span of the membrane.At the same time,the effects of the concentration of activated carbon on the anti salinity fluctuation,pH fluctuation,and the low C/N,COD,ammonia nitrogen,nitrite nitrogen,dissolved organic matter,extracellular polymer and flux were studied.The quantitative evaluation of PAC dosage on membrane bioreactor in the mariculture wastewater treatment and the optimum dosage of active carbon were determined.The results showed that:（1）PAC dosing was 1g·L^-1,the COD removal rate of membrane bioreactor was 96%,the ammonia nitrogen removal rate was 99%,the concentration of Nitrite nitrogen was less than0.05mg·L^-1.The PAC/MBR is suitable for marine aquaculture wastewater,the effect was obvious;（2）Salinity shock weakened the ability of MBR’s removing contaminants,adding powder activated carbon reinforced MBR on the pollutant removal efficiency,increased the EPS content in the floc、sludge particle size,the sludge hydrophobicity,which were beneficial to retarding membrane fouling;（3）when the pH rose from 6.8-7.5 to 9.5,the content of nitrite had a increasing trend,the condition of weak alkali was deteriorated sludge mixed liquor filtration performance;For PAC/MBR,the effluent content of nitrate nitrite decreased gradually,the nitration reaction carried out smoothly,PAC increased the activity of nitrifying bacteria,strengthened the membrane bioreactor to pH shock.（4）Under the low C/N,which showed that PAC was in the form of biofilm,that could improve the resistance to the toxic substances,which is conducive to the establishment of a microbial ecosystem.The flux of PAC/MBR from the original 132L/m²h·bar slowed down to 72L/m²h·bar,the MBR was 36.6L/m²h·bar,The flux decline of MBR was obvious;PAC could adsorb organic compounds and provide a carbon source for denitrification,which was conducive to denitrification and carried out simultaneous nitrification and denitrification.For MBR,it was very difficult to proceed denitrification under the effect that carbon source was not sufficient.