Study On Treating Hospital Sewage By Combining Enhanced Coagulation With Chlorine Dioxide Disinfection

On the purpose of improving and planning sewage treatment of small and medium hospital and rural medical institutions, the study of dealing with hospital sewage by combining enhanced coagulation with chlorine dioxide disinfection is researched. This study is divided into three parts:In the first part of the paper, the condition which include the kind of flocculant, the dosage of flocculant, complex ratio. pH and temperature of sewage is researched by orthogonal and single-factor experiment. In the study, PAC, PFS or PAFC is chose as flocculant, while PAM is chose as coagulant aid. In the second part of the paper, kinetics of formatting floc is study preliminarily in the enhanced coagulation according to the relationship between the change rate of floc concentration and floc concentration. In the third part of the paper, the affect of the dosage of chlorine dioxide and action time on disinfection and materialized index is researched, then the study of disinfect affect on hospital sewage is researched.The results show that the impact degree of the condition is that the dosage of PFS>temperature>pH>the kind of flocculant>the dosage of coagulant aid; the coagulation effect of PFS is the best among the three kind of inorganic flocculants, and the best coagulation condition is that the complex ratio between PFS and PAM is 50:1, the dosage of PFS is 187.5mg/L, the dosage of PAM is 3.75mg/L. pH is 8.0 and the coagulation temperature is 15～20℃, the flocculation kinetic equation is v=dc/dt=1.76×10-4c1.15; The best dosage of chlorine dioxide and action time is certain, which is that the dosage of chlorine dioxide is 20mg/L, action time is 15min. The sum of fecal coliform of the out water less than 10, Salmonella and Shigella are killed. It has not abvious effect on materialized index in thel～30 mg/L dosage of chlorine dioxide.By all of the study, the effect of treating is sumed, such as the removal of CODcr, NH3-N, turbidity and SS is 72.2%,14%,97.7% and 87.5%, the average kill rate of E. coli is 99.99%, the average kill rate of staphylococcus aureus is 99.98%. The paper show that treatment by combining enhanced coagulation with chlorine dioxide disinfection is effective method for removing CODcr, especially for removingturbidity, SS. fecal coliform, Salmonella, Shigella. But the removal rate of NH3-N is small, so the further research is urgently needed.