Mechanism On Iron Oxyhydroxide Affecting On Characteristics Of Biological Phosphorus Removal

The eutrophication of water bodies is a major environmental problem faced by society today,and phosphorus is a limiting factor that leads to eutrophication of water bodies.Therefore,it is necessary to control the phosphorus content in the effluent of municipal wastewater plants.The biological phosphorus removal method is the mainstream phosphorus removal technology in urban sewage plants.This paper aims at the technical difficulties of biological phosphorus removal in municipal wastewater treatment plants.By adding iron oxyhydroxide to biological phosphorus removal system,its effect on biological phosphorus removal characteristics and its mechanism of action on biological phosphorus removal characteristics are revealed.Iron oxyhydroxide under low temperature conditions can improve the efficiency and rate of biological phosphorus removal,and the effluent TP meets the discharge standard of Class IA.Iron oxyhydroxide can effectively reduce the swelling of sludge under low temperature conditions,promote the secretion of protein and polysaccharide in EPS,increase the activity of biological phosphorus removal enzyme,and thus enhance the phosphorus removal performance of low temperature biological phosphorus removal system.At the same time,iron oxyhydroxide increases species abundance and microbial diversity in biological phosphorus removal systems,enriches Proteobacteria,and inhibits the growth of bacterial flora such as Bacteroidetes,which promotes sludge flocculation and sedimentation.Plays an important role in the growth of microbial flora Zoogloea.The type and concentration of carbon source affect the phosphorus removal characteristics of the coupling process of iron oxyhydroxide and biological phosphorus removal.Under the C/P ratio of 30,the phosphorus removal efficiency of the acetate and propionate groups was maintained above 95%,and the phosphorus and phosphorus uptake rates were high.In the glucose group,the phosphorus removal efficiency was unstable,and the phosphorus release and phosphorus uptake rates were low.The C/P ratio decreased from 30 to 20,the phosphorus removal capacity of the three reactors decreased,the acetate group was the most affected,and the propionate group was the least affected.The C/P ratio rose to 30,and the phosphorus removal capacity of the three reactors was difficult to recover.Overall,EPS secretion was highest in the acetate group,but the MLVSS value was the lowest;the VSS/SS values of the three groups of reactors showed an upward trend,and the increase in their values corresponded to the decrease of the phosphorus removal ability.The increase in the abundance of nitrating bacteria such as α-proteobacteria and Nitrospirae in the three reactors was the main reason for the decrease in phosphorus removal capacity.Iron oxyhydroxide reduces phosphorous removal capacity of biological phosphorus removal system with acetate as carbon source.Iron oxyhydroxide inhibits the phosphorus accumulating bacteria in the biological phosphorus removal system and the phosphorus removing function of the EPS,which makes the glycine bacteria occupy an advantage in the competition with the phosphorus accumulating bacteria,reduces the PHAs synthesis and consumption rate in the biological phosphorus removal process,and promotes the biological In the phosphorus removal system,the metabolic pattern of phosphorus accumulating bacteria turned to the metabolic mode of glycan bacteria.Iron oxyhydroxide promotes the secretion of proteins and polysaccharides from EPS and increases the activity of activated sludge dehydrogenase.