Research On Mechanism And Application Of Enhanced Coagulation

Recently years,with increament of water quality standards,conventional water treatment technolygy are facing challenge.Coagulation which attacts more concern in transformation of traditional process is an important part in conventional water treatment process.Enhanced coagulation is an important technolygy of control DBPs and other micro-pollution beacause of high efficiency of organic matter.In this paper,a series key problems was studied.Is interaction between ozone and coagulant in ozone-coagulant combine process? What was interaction? What are the influences of interaction on water quality?FeCl₃ and Al Cl₃ are used as coagulant in this study because of they are conventional coagulants.This paper mainly study effect of coagulation on TOC removal,Sstructural characteristic of residual TOC,effect and mechanism of DBPFP and change of oxidants in SOC（O₃ and coagulant added at the same time）and POC（add coagulant afre pre-ozonation for 4h）.Study show that there was notable difference between SOC and POC.Interaction beitween ozone and coagulant really exist.It proves interaction between ozone and Fe/Al coagulant exist.Interaction vary with different coagulant.In ozone-Fe coagulant combined process,interaction is catalytic of Fe-coagulant on ozonation organic matter.In ozone-Al coagulant combined process,interaction is adverse effect of ozone on coagulation.The interaction was reflected in oozne stock,presence of secondary oxidants（OH·）and conrresponding changes with the stock of coagulants.SOC and POC posses significant difference in turbidity,organic matter removal rate,residual organic structure（UV difference absorption,3D-EEM spectrum）,DBPFP.Interaction show different characteristics combined with different coagulant.In ozone-Fe/Al coagulant combined process,effect on turbidity,UV,fluorescence intensity,HAAFP and THMFP of POC is better than SOC.But there are difference.In ozone-Fe coagulant combined process,effect of SOC on TOC is better than POC.In ozone-Al coagulant combined process,effect of POC on TOC is better than SOC.In ozone-Fe coagulant combined process,removal of TOC is determined by coagulation.When coagulant dosage was 1 and ozone dosage was 0,1,2,residual TOC was 6.39mg·L^-1,6.38 mg·L^-1,6.37 mg·L^-1 respectively.When coagulant dosage was 3 and ozone dosage was 0,1,2,residual TOC was 4.59 mg·L^-1、4.53 mg·L^-1、4.25 mg·L^-1respectively.Interaction of SOC group was enhanced by increasing coagulant dosage.1^-1,removal efficiency of POC on TOC is 21.4%,SOC is 24.14%.1-3.removal efficiency of POC on TOC is 37.46%,SOC is 45.49%.Improving coagulant dosage,the difference between SOC and POC was amplified.In ozone-Fe coagulant combined process,adverse effect of ozone on HAAFP should be considered.When dosage of ozone and coagulant was 1-3,HAAFP of SOC was 40.61μg·L^-1.2-3,HAAFP of SOC was 60.37μg·L^-1.Effect of ozone on HAAFP was slight.1-3,HAAFP of SOC was 90.23μg·L^-1,2-3,HAAFP of SOC was93.22μg·L^-1。When ozone combine with Fe/Al coagulant,effect of ozone on organic matter was different.The effect of Fe coagulant on TOC remove,HAAFP,THMFP was better than Al coagulant.In ozone-Fe coagulant combine process,efficience of SOC on TOC remove is 24.02%,POC is 21.4%.HAAFP and THMFP of SOC are 66.94μg·L^-1 and 112.7μg·L^-1,POC are 60.65μg·L^-1 and 104.91μg·L^-1.In ozone-Al coagulant combine process,efficience of SOC on TOC remove is 37.41%,POC is 44.31%.HAAFP and THMFP of SOC are 76.46μg·L^-1 and 117.35μg·L^-1,POC are 68.65μg·L^-1 and 107.96μg·L^-1.