Enhanced Sequencing Batch Activated Sludge System With Macrorotous Lanthanide Hydrogel Study On Phosphorus Removal Efficiency

The problems of water eutrophication caused by phosphorus in water body and the shortage of phosphorus resources need to be solved urgently.Adsorption method can work together with biological phosphorus removal method,which solves the disadvantage of unstable effluent of biological method and avoids the problem of excessive surplus sludge produced by chemical phosphorus removal method.Hydrogels have good hydrophilicity,and can introduce groups through functional design to enhance the ability of adsorbing phosphorus,and can achieve the purpose of separating from sewage by controlling its shape and size.The addition of GO can make up for the poor mechanical strength of hydrogel.Lanthanum has a strong affinity for phosphorus,and its presence can have a certain effect on the growth of organisms.In this study,using lanthanum carbonate,graphene oxide and sodium alginate as raw materials,the macroporous lanthanum hydrogel（CH-La SA）was synthesized with the assistance of Ca CO₃+HCl pore-forming.The adsorption capacity and mechanism of CH-La SA for phosphorus were investigated,and the influence of CH-La SA on activated sludge in SBR reactor was studied.CH-La SA hydrogel adsorbent is grey-black spherical,has a strong mechanical strength,is a mesoporous material,can successfully adsorb phosphate;The maximum adsorption capacity of CH-La SA hydrogel adsorbent for phosphorus was 231.6 mg P/g.In the process of p H=2-8,the adsorption capacity increased with the increase of p H,while the adsorption capacity decreased slightly when p H continued to rise.Coexisting anions have little influence on the competitive adsorption of phosphate,and the degree of influence on the adsorption capacity is as follows:Si O₃^2->SO₄^2->CO₃^2->NO₃^->Cl^-,the existence of Si O₃^2-can lead to a 20%decrease in the adsorption capacity,which may be because silicate is easy to form a complex with lanthanum;The pseudo-second-order kinetic model can better describe the kinetic experimental results,proving that chemisorption is the main rate-limiting step in the process of CH-La SA adsorbent adsorption of phosphate.CH-La SA hydrogel has the best desorption effect under the condition of 0.1 mol/L HCl,and the adsorption capacity can reach 63%of the original,which is still valuable and can reduce the economic cost of the use of adsorbent.In the SBR reactor system,the addition of adsorbent has no obvious effect on the COD,NH₄⁺-N,TN and p H of the effluent,but significantly reduces the TP of the effluent.After the addition of adsorbent,all effluent indexes meet the discharge standard of Grade A,and the 10mg/L adsorbent dosage group has the best effluent effect.The addition of adsorbents directly led to the secretion of a large number of extracellular proteins.After the smooth operation of the reactor,evidence showed that the presence of adsorbents with the dosage of 20 mg/L or less stimulated the growth of proteins,and the concentration of extracellular polysaccharides remained unchanged.Low doses of additive had no obvious effect on sludge morphology,also can promote the growth of the sludge,improve sludge flocculation and dewatering performance,improve the organic matter content in the sludge,and increase the phosphorus content of sludge,is good for phosphorus removal and recycling,high dose of the adsorbent can lead to loose sludge,a certain degree of negative influence on growth of sludge.For the SBR reactor designed in this experiment,the dosage of 10 mg/L is the best dosage for phosphorus removal.