Effect Of D-amino Acid On MBR Process For The Treatment Of Corn Starch Wastewater

With the rapid development of corn processing industry,the treatment of wastewater from corn starch is urgent.Membrane bioreactor(MBR)and its combination process have obvious advantages in the treatment of corn starch wastewater,but the membrane fouling problem still restricts the application of this technology.Membrane pollution includes physical pollution,chemical pollution and biological pollution.D-amino acid can inhibit the formation of bacterial biofilm,which is the latest membrane fouling control strategy.This study discusses the D-amino acids of E.coli bacteria(single)and activated sludge(mixed bacteria)biofilm formation,the influence of monitoring the delivery cycle for 24 h,concentration of 50 μM Dtyrosine influence on MBR effluent water quality situation,examines the D-tyrosine under the action of the MBR membrane pollution situation,and analyses the mechanism of D-tyrosine reduce membrane pollution.The results showed that:Five D-amino acids(D-tyrosine,D-leucine,D-tryptophan,D-aspartic acid,and D-arginine)mainly inhibit the synthesis of polysaccharides and proteins in EPS,reduce the formation of biofilm biomass,and finally inhibit the formation of Escherichia coli and activated sludge biofilm by affecting the initial adhesion of Escherichia coli and activated sludge.At the same time,D-tyrosine had the best effect.D-tyrosine could reduce the biofilm biomass of E.coli and activated sludge by 25.79%and 24.37%,respectively,reducing the contents of polysaccharide and protein in Escherichia coli EPS by 38%and 49%,respectively,and reducing the contents of polysaccharide and protein in activated sludge EPS by 30%and 11%,respectively.The regular addition of D-tyrosine does not affect the effluent quality of MBR treatment of corn starch wastewater.The MBR adding D-tyrosine can remove 92%COD and 75%ammonia nitrogen,and the contents of nitrate and nitrite in the operation process are 14 mg/L and 2 mg/L,respectively.The MBR adding D-tyrosine has the same removing effect on COD and ammonia nitrogen as the blank control MBR.The addition of D-tyrosine had no effect on the nitrification process.The MBR with D-tyrosine for the removal of positive phosphorus,total phosphorus and total nitrogen were 35%,37%and 39%,respectively,which were basically the same as the blank control MBR,indicating that MBR for the removal of positive phosphorus,total phosphorus and total nitrogen in corn starch wastewater is not high,and it needs to be combined with other processes for nitrogen and phosphorus removal.The critical flux experiment and short-term extracellular polymer(EPS)filtration experiment showed that the addition of D-tyrosine could reduce the fouling potential of activated sludge membrane.The critical flux experiments,short-term filtration experiments of EPS and SMP showed that the addition of D-tyrosine could reduce the membrane fouling potential of the activated sludge mixture and EPS,but had little effect on the membrane fouling potential of SMP.Further analysis the MBR polysaccharide and protein content in the activated sludge SMP and EPS,three dimensional fluorescence spectrum and particle size distribution,basic properties of activated sludge,sludge floc size distribution,Zeta potential,etc.,found that Dtyrosine regularly to join in the inhibition of activated sludge EPS production of polysaccharide and protein,change the particle size distribution,the average particle size decreases;D-tyrosine had no significant effect on the contents of polysaccharide and protein in SMP,but could increase the average particle size.D-tyrosine can reduce the proportion of small particle size components in activated sludge floc,reduce the Zeta potential of SMP and EPS,and alleviate membrane fouling mainly by inhibiting the secretion of polysaccharide and protein in activated sludge EPS and reducing the proportion of small particle size components in activated sludge floc.