Spatial Distribution Characteristics Of Typical Extracellular Enzymes In EPS In The Process Of Sewage Biological Treatment

Biological treatment is widely used in sewage treatment system,but the removal efficiency of biological treatment for macromolecular refractory organic matter is low.Therefore,strengthening the decomposition effect of biological treatment system on refractory organic substances is a significant issue to improve the efficiency of biological treatment.The activity of extracellular hydrolase and oxidoreductase is an important factor affecting the removal efficiency of macromolecular refractory organic compounds.To study the distribution and activity of typical extracellular enzymes in extracellular polymeric substances(EPS)in the biological treatment system of municipal wastewater and industrial wastewater is the premise of enhancing the effect of extracellular enzymes.In this research,the distribution and activity of typical extracellular hydrolase in sludge from different treatment units of municipal sewage treatment plant and typical oxidoreductase in sludge from different biological treatment units of textile wastewater treatment plant are studied.Then,the distribution and activity changes of extracellular hydrolase or oxidoreductase in sludge under different pollutant impact loads are investigated,and the roles of extracellular hydrolase or oxidoreductase in the removal of pollutants in different layers are analyzed.The main conclusions of this research are as follows:(1)The total activity of protease and α-amylase in aerobic zone is the highest among the three biologiacal treatment units of actual municipal wastewater treatment plant.The total activity of α-glucosidase in the anaerobic zone is the highest,while the total activity of phosphatase in the anoxic zone is the highest.The activities of protease,α-amylase andα-glucosidase in tightly bound EPS(TB-EPS)are the highest,while the phosphatase activity are the highest in loosely bound EPS(LB-EPS).(2)Under the influence of phenol,the total activity of extracellular protease decreases first and then increases in the anaerobic phase phase,and then decreases slightly in the aerobic phase.During two reactive phases,the protease activity in slime-EPS is highest.Under the influence of starch,the total activity of α-glucosidase increases first and then decreases during two reactive phases.The total activity of α-amylase increases gradually.The α-amylase activity in LB-EPS is highest,and the α-glucosidase activity in TB-EPS is highest among three layers of EPS.Under the influence of phosphate,the total phosphatase activity decreases first and then increases during two phases.The phosphatase activity in TB-EPS is highest in each phase.(3)The total activities of azo reductase,laccase and lignin peroxidase in EPS of anaerobic tank are the highest among the four biochemical tanks in the textile wastewater treatment plant.In three layers of EPS in each tank,azo reductase and lignin peroxidase are mainly distributed in TB-EPS,while laccase was distributed only in slime-EPS and LB-EPS.(4)Under the influence of aniline,the total activity of laccase increases gradually in the anaerobic and aerobic phase,while the total activity of lignin peroxidase increases first and then decreases.During the whole reactive period,the lignin peroxidase activity in TB-EPS is the highest,and the laccase activity in slime-EPS is the highest.Under the influence of acid orange 7,the activity of lignin peroxidase in the anaerobic phase is higher than that in aerobic phase,and the total activity of laccase gradually increases.But the activity of azo reductase has no significant change.In two phases,the activities of lignin peroxidase and azo reductase in TB-EPS are higher,while the activity of laccase in slime-EPS is higher.(5)The distribution of different extracellular enzymes in EPS is different and varies with the impact of pollutants.In municipal wastewater treatment system,protease,α-amylase andα-glucosidase are mainly distributed in TB-EPS,and phosphatase is mainly distributed in LB-EPS.Under the influence of phenol,protease is mainly distributed in slime-EPS;phosphatase is mainly distributed in TB-EPS under the influence of phosphate.Under the influence of starch,α-amylase is mainly distributed in slime-EPS and LB-EPS,and α-glucosidase is mainly distributed in TB-EPS.In textile wastewater treatment system,lignin peroxidase is mainly distributed in TB-EPS,and laccase is mainly distributed in LB-EPS.The distribution of azo reductase in three layers of EPS is uniform.Under the influence of aniline,lignin peroxidase is mainly distributed in TB-EPS,and laccase is mainly distributed in slime-EPS.Under the influence of acid orange 7,lignin peroxidase and azo reductase are mainly distributed in TB-EPS,and laccase is mainly distributed in slime-EPS.