Treatment Of Anaerobic Digestate From Cattle Manure By Membrane Aeration Biofilm Reactor

As a technology that can reduce environmental pollution and generate new energy,anaerobic fermentation technology is currently used in the treatment of livestock and poultry wastewater.The anaerobically digested cattle manure slurry after anaerobic fermentation still contains a lot of impurities such as nitrogen,phosphorus and organic matter.If it is improper ly treated,it will cause secondary pollution,and the general sewage treatment technology can not remove the pollutants well.Membrane aeration biofilm reactor(MABR)technology has attracted much attention for its unique advantages in the treatment of refractory organic matter.However,with the current research,there are few studies on the operating parameters of slurry.Therefore,the effect of different operating parameters on the technical treatment effect and change trend of MABR reactor is investigated by response surface methodology,and the operating parameters are optimized.The long-term experiment of simulating anaerobically digested cattle manure slurry and actual anaerobically digested cattle manure slurry was carried out by optimizing the parameters.Analyze the law of MABR reflection and the succession of biome in the process of treating sewage,and provide a new technology for the treatment of ox anaerobic fermentation liquid,and provide reference for its practical application.In the parameter optimization experiment,the response surface method was used to determine the best combination according to the optimization result with the lowest concentration of effluent pollutants: hydraulic retention time 24 h,water flow velocity 90 r/min,in fluent ammonia nitrogen concentration 40 mg/L,COD The concentration is 800 mg/L and the phosphate concentration is 10 mg/L.After verification,the model predicts good results and can provide data reference for practical applications.After the parameter optimization process,the effect of high carbon and nitrogen load shock on the removal rate of pollutants was investigated by simulating the long-term operation of anaerobic fermentation liquid.Domestication increased the surface load so that the biofilm had the ability to process the actual anaerobically digested cattle manure slurry.The results showed that when the ammonia nitrogen concentration was increased from 40 mg/L to 120 mg/L,the removal efficiency was reduced from 95% to 65%.When the carbon source is sufficient,the nitrite nitrogen content of the effluent is as low as 2 mg/L,the nitrate nitrogen is 3 mg/L,the nitrite nitrogen concentration is up to about 7.5 mg/L when the carbon source is insufficient,and the nitrate nitrogen is about 19 mg/ L.The total nitrogen removal rate is about 45% lower when the denitrification is blocked,and more than 90% when the carbon source concentration is increased.For the COD removal rate is always maintained at about 90%,it means that MABR has a great advantage in COD removal.The domesticated MABR has good resistance to external impact and has certain adaptability to high-concentration wastewater.The biofilm can be used for the anaerobically digested cattle manure slurry removal experiment of the next stage.Investigating the effect of MABR on the treatment of anaerobically digested cattle manure slurry with different dilution ratios,it was found that the removal rate of ammonia nitrogen was always about 90%.The concentration of nitrate nitrogen drops sharply after the addition of carbon source,and the final stage is stable at about 5 mg/L.Phosphate removal rate has continue increasing,the phosphate removal rate is 35% at last.In terms of COD removal,the removal rate can be restored to about 85% after two influent load shocks.It can be seen that MABR has the ability to adjust to various carbon sources,and can treat anaerobically digested cattle manure slurry properly.In terms of biocharacterization,sludge in reactors showed better biodiversity than the original sludge,which was clearly observed under scanning electron microscopy.Particularly,the reactor that has treated the slurry showed more euglypha,indicating that the effuent water quality was better.In this experiment,high-throughput sequencing was used to analyze the difference s between the inner and outer layers of the biofilm.It was found tha t the inner layer was mostly filled with Nitrospira which is used for nitrification,and the inner layer of the simulated slurry reactor was also found.Thauera,which has a larger proportion than the original sludge.The dominant bacteria in the outer layer are Denirtatisoma which is a carbon-depleting anaerobicaceae.The outer membrane of the actual slurry reactor is also found to account for 12% of the denitrifying polyphosphates(Clostridium)and so on.These all explain the reason of decarburization and nitrogen removal of MABR from a microbiological point of view.