The Enhanced Flocculation Technology Of Forms Matching With Suspended Solids And Precursors Of Disinfection Byproducts In Water

With the industrialization and modernization has improved continuously, total amount of pollutants emitted to the natural water increase sharply, Far beyond the self-repair capacity of water environment, and it was overall polluted, including drinking water sources. Therefore, the safety of drinking water and sanitation Including micro-polluted source water treatment and control, has become a hot issue of the environmental studies field.This paper relies on the "The Key Technology for Purification and Demonstration of Micro-polluted raw water" which is the sub-topics of "Water Pollution Control and Harnessing of the Major Projects" (subject No.2008ZX07421-004) customised research which is attributable to the national "Eleventh Five-Year Plan ". Based on the existing relevant research home and abroad, with the actual characteristics of Shanghai Huangpu River source water, this article wants to establish a matching relationship of flocculants, pretreatment agents and the characteristics pattern of organisms and DBPs, and to seek a effective and safe mathod of drinking water treatment to reduce precursors of disinfection byproducts(DBPsFP) concentration and control the organic matter and turbidity in raw water, to guide the actual operation in water supplier. Results are as follows:(1)By testing, Huangpu River raw water turbidity was 78.7 NTU, DOC detection is 4.76mg/L, particle size mainly concentrated in the 10-100um, Zeta potential of electricity is negative charge, Cl-, SO4-, NO3- contents were 59.36mg/L,78.34 mg/L,1.88 mg/L(2)The author used the flocculants of A12(SO4)3,PACl (30%Al2O3),Ferric Polymerization and efficient PAC. Measured by conventional coagulation experiments, PAC has good for DOC's targeted removal in the four flocculants,12 mg/L dosage the removal rate is about 50%. PAC(30%) and Al2(SO4)3 has good for UV254, the removal ability increases with the flocculants dosage, the highest removal abilities are 50% and 47% separately in addition to 15 mg/L dosage. In the dosage changes from 6mg/L to 8 mg/L, isoelectric point of colloidal appears, corresponding to the maximum turbidity and DOC removal rate. Determine the optimal dosage of flocculants 8mg/L(Al). (3)KMnO4 and FeCl3 as pretreatment agents, the author did the chemical pre-oxidation enhanced flocculation, can also improve the removal efficiency of TOC and UV254. Al2(SO4) 3 as flocculant,the TOC removal ability of enhanced flocculation is higher by 10% than regular flocculation, the compositional formulation 0.8mg/L FeCl3 with 0.8mg/L KMnO4 emoval of TOC and UV254, respectively, than the conventional flocculation increased by 10% and 7%.(4)In raw water Molecular Levels, molecular weight of less than 3,000Da organic matter accounted for the largest proportion of the total content in water. The UV254 and TOC both accounted for more than 30% of raw water total content, and this part of the organic disinfection by-products generated the highest activity. Enhanced coagulation can controls thet DBPsFP stronger than conventional flocculation.(5) In the productive of continuous pilot experiment with the flocculants of Al2(SO4)3, I-PAC and H-PAC, H-PAC for the Potassium Permanganate Index, UV254, DOC removal rates are 30%~35%,40%～45%,30%-35% for their own under conventional flocculation process, higher than that of other flocculant ranging from 5% to 10%. Pre-oxidant compound dosage of the organic removal rate increased by 5% compared with conventional process using Al2(SO4)3 as flocculant; I-PAC to be flocculant, strengthen the role of pre-oxidation of KMnO4 organic removal process than the conventional 5%; H-PAC as a contrast, FeCl3 pre-oxidation process on the removal Potassium Permanganate Index increased by 7% compared with conventional process, but KMnO4 pre-oxidation process on the removal rate of UV254 and DOC, respectively, than the conventional process by 5% and 10%.(6) Three were increased dosage of flocculants Al2(SO4)3, I-PAC and H-PAC, Potassium Permanganate Index, UV254 and DOC reveal increasing trends in the overall removal efficiency. When Al2(SO4)3 coagulant,1.25,1.50,1.75 times the dosage, the Potassium Permanganate Index removal rate increased by 3%,3%,5% compared with the corresponding conventional technology, DOC removal rate increased by 2%,10%,10% at the same time. I-PAC as flocculants, FeCl3, KMnO4 separate pre-oxidation and complex dosing, total THMs lower than the corresponding conventional technology 40ug/L,30ug/L,25ug/L. Increase the amount of flocculant for removal of DBPs have a positive effect, each component can be removed with the amount of flocculant increases. In summary, the following recommendations parameters, using Al2(SO4)3 as coagulant, the dosage of 45mg/L(Al2(SO4)3·18H2O), FeCl3 and KMnO4 two pre-dosing of pharmaceutical pre-oxidation at the same time, the same dosage was 0.6mg/L (FeCl3 to total Fe, KMnO4 to KMnO4 account). Suggested a higher concentration of organic matter in raw water situation, an appropriate flocculant dosage increased to 1.25 times the normal dosage is appropriate.