Study On Nitrogen And Phosphorus Removal And Colony Characteristics Of Aerobic Granular Sludge And Biofilm Reactor

Due to its advantages of compact structure,good settling ability and high pollutant degradation ability aerobic granular sludge(AGS)has been widely concerned by researchers all of the world.At present,the sewage plant with AGS as the main technology has been built in foreign countries,and the effluent quality is good,but there are still some shortcomings such as long period of granular sludge,small size of grain,easy disintegration and so on.How to quickly obtain AGS with large particle size,biodegradability and stability is one of the hot topics at present.Biofilm method is relatively mature in engineering application,and the development of fillers also promotes the development of biofilm technology.There are aerobic / anoxic / anaerobic microenvironment in both AGS and biofilm,and all of the two have good biological denitrification and phosphorus removal ability.The removal effect is greatly influenced by the type of carrier,operation mode and water matrix.The effects of addition of poly aluminum chloride and fine granular activated carbon on the formation time,particle size,settling property and denitrogenation and dephosphorization ability of AGS in batch reactor were studied.At the same time,the characteristics of nitrogen and phosphorus removal and microbial population were compared with four different carrier biofilm reactors.The four biofilm reactors used four kinds of carriers,such as soft composite packing(MPU+ fiber ball + BC-B1-10-8),PE-5 hard filler,PE-7 hard filler and soft modified polyurethane sponge.All biofilm reactors were operated in 2 modes,sequencing batch and continuous flow.The results of the study show that:(1)Adding fine carrier can effectively shorten the sludge granulation time and increase the particle size of the sludge.The sludge granulation time was shortened from 29 d to 19 d,compared with that without loading.The size distribution of D40 in the 3 groups(40% of the total amount of sludge in the grain size at this interval)is 324 ?m ~612 ?m(adding granular activated carbon),312 ?m ~514 ?m(adding polyaluminum chloride)and 173?m ~343 ?m(no loading body),and the granular activated carbon shows a stronger promotion effect.(2)The activity of sludge was characterized by oxygen consumption rate,and the activity of sludge showed different effects according to the dosage of PAC.When the amount of polyaluminum chloride is more than 100 mg/L,the oxygen consumption rate of the sludge will decrease with the increase of the dosage;the oxygen consumption rate of the sludge is 0.25 mg/(g MLSS.min)when the dosage is 100 mg/L,and the time of addition is 0.23 mg/(g MLSS.min),which indicates that a proper amount of polychlorinated aluminum will make the sludge more active.(3)Adding fine particles can promote the production of extracellular polymeric substances in sludge during the formation of AGS.In the course of AGS formation,the content of protein and polysaccharide has kept increasing trend.Compared with non loading,granular activated carbon promoted the secretion of protein from sludge better than polyaluminum chloride.Granular activated carbon was added to the sludge,the protein content increased from 24.32 mg/g MLSS to 52.45 mg/g MLSS,the polysaccharide increased from 21 mg/g MLSS to 27 mg/g MLSS;the sludge protein added to the polyaluminum chloride increased to 48.12 mg/g MLSS and the polysaccharide increased to 26 mg/g MLSS;the unadded sludge increased to 48.07 mg/g MLSS,polysaccharide.Increase to 23 mg/g MLSS.(4)Under the condition of the same water quality,the operation results of aerobic granular sludge reactor and biofilm reactor(using sequencing batch and continuous flow)showed that the concentration of COD was in the range of 480 mg/L~800 mg/L,and the removal rate of COD was above 90%.The influent NH4+-Noncentration is 18.32 mg/L~45.87 mg/L,and the removal rate of NH4+-N is 95.45%(AGS reactor),94.96%(biofilm reactor continuous flow reactor)and 90.66%(biofilm reactor intermittently operation).When the concentration of the influent TN is increased to 70.25 mg/L,the removal rate of TN is 83%(AGS reactor)and 53.02%,respectively.(biofilm reactor continuous flow reactor)and 71.29%(sequencing batch biofilm reactor).When the concentration of PO43--P was increased from 7 mg/L to 8.5 mg/L,the removal rate of PO43--P was 87%(sequencing batch biofilm reactor),75%(continuous flow biofilm reactor)and 85%(AGS reactor).(5)From the molecular biology point of view,the mature AGS and biofilm all have the characteristics of the diversity of the bacteria.From the gate level analysis,mainly deformable bacteria(Proteobacteria),actinomycetes(Actinobacteria),and green sulfur bacteria(Chloroflexi).Under the same organic loading and operation mode,the abundance of bacteria in aerobic granular sludge and different carrier biofilms was different.The carrier with larger specific surface area is beneficial to the growth of Proteobacteria,and the abundance of Proteobacteria in AGS,soft filler and hard stuffing biofilm is 25.32%,62.5% and 49.83%,respectively,and the abundance of Actinobacteria in AGS,soft fillers and hard stuffing biofilms respectively is 28.62%,7.25% and 38.92%,and Chloroflexi is soft.The abundance of biofilm in packed biofilm was 2.12%,higher than that in rigid biofilm and AGS.