Application Of Chitosan Complex Coagulation Technology In Micro-polluted Water Treatment

With the increase in water pollution,many water sources have been polluted to v arying degrees,and some organic matter in the water body has exceeded the standard of Class III water in the "Surface Water Environmental Quality Standards",showing a slightly polluted water state.Coagulation as the main process of water supply plant,it s treatment result generally depends on the coagulant used.At present,metal ion coagu lants such as polyaluminum chloride are commonly used,which have good performan ce and high cost performance,but the hidden safety problems caused by them have pr ompted people to study natural polymer coagulants.In this paper,the principle of com plex coacervation is applied to water treatment.Chitosan(CS)and CarboxymethyL cellulose sodium(CMC),chitosan and Sodium ALginate(ALG)is two kinds of comp osite coagulant for substrate.The coagulation effect,influencing factors and removal mechanism of the coagulant were investigated.The research results are as follows:(1)The CS-CMC dosage of 20mg/L each time achieves the best coagulation effe ct on kaolin suspension,and the turbidity removal rate reaches 98.13%.When CS-AL G dosage is CS dosage 10mg/L and ALG dosage 20mg/L,the coagulation effect is the best and the turbidity removal rate reaches 97.87%.Compared with PAC,CS-CMC an d CS-ALG have the advantages of less dosage and shorter settling time.The experime ntal results of the flota Zeta potential and particle size indicate that the main mechanis m of action of the two coagulants is electrical neutralization,and there are both net tra pping and adsorption bridging.(2)When the dosage of CS-CMC is 25mg/L each,the effect of adsorbing humic acid solution is the best,and the humic acid removal rate reaches 97.01%.When the d osage of CS-CMC was 55mg/L each,the coagulation effect of the mixed solution of h umic acid and kaolin suspension was the best,the turbidity removal rate reached 99.22% and the humic acid removal rate reached 98.21%.Compared with PAC,CS-CMC has higher removal efficiency of organic matter,and there are differences in the scope of application.(3)When the dosage of CS-CMC system is 20mg/L each,the coagulation effect of the mixed solution of pyridine and kaolin suspension is the best.The turbidity removal rate of the mixed system can reach 97.4%,and the pyridine removal rate can reach34.5%.However,under the same optimal conditions,PAC has almost no removal effe ct on pyridine.(4)When the dosage of CS-CMC system is 30mg/L each,the coagulation effect of the raw water of the Yellow River reaches the best,and the turbidity removal rate r eaches 99.38%.When the dosage of CS-CMC was 75mg/L each,the coagulation effe ct of the humic acid yellow water raw water mixed system reached the best.At this ti me,the turbidity removal rate of the raw water was 99.81% and the humic acid remov al rate was 94.96%.When the dosage of CS-CMC was 30mg/L each,the coagulation e ffect of pyridine yellow river raw water reached its best,the turbidity removal rate rea ched 99.35%,and the pyridine removal rate was 39.6%.After the CS-CMC coagulati on treatment,the Yellow River water can meet the drinking water treatment water qua lity standards after the subsequent conventional treatment,and has a greater effect on t he removal of organic matter in the influent,reducing the subsequent treatment load,r educing the pressure of the subsequent treatment,and reducing the treatment cost.