Experimental Research On Enhanced Coagulation For Treatment Of Huai He Micro-polluted Water

Huaihe river was important drinking water source for Huainan water treatment plant, the source water quality of Huaihe river fluctuates greatly with variation of seasons, in winter, NH3-N was difficult to be removed. According to the Huaihe water with micro-polluted characteristic, selected the combination of polyaluminum chloride (PAC) and powdered zeolite as enhanced coagulation treatment to improve the coagulation efficiency, and determined the parameters for the transformation of water treatment plant.The best coagulant was presented:the PAC was better than the FeCl3. when the optimal dosage of PAC was added, the CODMn, UV254, NH3-N and turbidity of sediment water will respectively be:2.75mg/L,0.062cm-1,1.19mg/L and 0.98NTU, the removal efficiency will be 34.5%,30.3%,21.1% and 98.1% respectively.The combination of PAC, diatomite and PAM enhanced coagulation was presented, studies showed that:when 9mg/L PAC, 100mg/L diatomite and 0.6mg/L PAM were added, the CODMn, UV254, NH3-N and turbidity of sediment water will respectively be 2.15mg/L, 0.045cm-1,0.97mg/L and 0.29NTU, the CODMn, UV254, NH3-N removal rates were respectively increased by 12.9%,18.1% and 10.2% compared with single dosing PAC.When 9mg/L PAC,18mg/L powdered activated and 72mg/L powdered zeolite were added, the CODMn, UV254, NH3-N and turbidity of sediment water will respectively be 1.95mg/L,0.033cm-1,0.78mg/L and 1.5NTU; 9mg/L PAC,15mg/L powdered activated and 75mg/L diatomite were added, the experimental date will respectively be 1.88mg/L,0.03cm-1, 0.79mg/L and 1.3NTU, compared with single dosing PAC, the CODMn, UV254, NH3-N removal rates were increased by about 20%,35% and 25%.Compared the combination of PAC, PAM and powdered zeolite with the combination of PAC and powdered zeolite the removal of NH3-N and organic was similar, selected the combination of PAC and powdered zeolite as the enhanced coagulation treatment, when 9mg/L PAC and 80mg/L powdered zeolite were added, the CODMn, UV254, NH3-N and turbidity of sediment water will respectively be 2.38mg/L,0.05cm-1,0.83mg/L and 0.74NTU, compared with single dosing PAC, the CODMn, UV254, NH3-N removal rates were increased by 8.8%,13.5% and 23.3% respectively.The combination of PAC, powdered activated and powdered zeolite (diatomite) could increase the removal rate of organic matter and NH3-N. But compared with the combination of PAC and powdered zeolite, the removal of NH3-N was similar, and the combination of PAC and powdered zeolite was more economical. Therefore enhanced coagulation for the combination of PAC and powdered zeolite had been proposed as a better feasible technology for NH3-N removal in winter.The equipment which inflow was 8m3/h was studied in the pilot scale, the combination of 3.6mg/L PAC and 80mg/L powdered zeolite enhanced coagulation treatment was used. The studies showed that:PAC and powdered zeolite enhanced coagulation made a good effect of improving water quality, the NH3-N removal efficiency will reach 30%.