Effects Of Drinking Water Treatment Process Optimization On Water Quality

With the improvement of people’s living standards and health conditions, thecognitions of people on the risks of disinfection by-products in water and the hazardsof carcinogenic organic and inorganic to health are deeper, the requirement ofdrinking water quality is also increasing. Let people drink safe and secure drinkingwater has become the focus of society. In this paper, based on our plant daily watersupply capacity of50,000tons, the actual daily water supply capacity of30,000tons,I study the improvement of the drinking water quality by process optimization,including the micro-vortex reaction pool to replace folded-plate reaction pool,“V”horizontal-tube sedimentation tank to replace inclined-tube sedimentation tank,the stability chlorine dioxide disinfection process to replace the traditional liquidchlorine disinfection and other technology upgrading, The main results were asfollows:(1)When source water flow was constant, the removal rates of post-optimalitymicro-vortex reaction pool on the turbidity, Fe, Mn, NH3-N, NO2--N and CODMnwere higher than the original folded-plate reaction pool. When the source waterturbidity increased to200NTU, the water turbidity after treated by folded-platereaction pool was more than5NTU. But at same condition, the water turbidity aftertreated by micro-vortex reaction pool was below3NTU, and the removal rate of Fe,Mn, NH3-N, NO2--N and CODMnwere higher than35%.(2)When source water flow doubled, the removal rates of micro-vortex reaction poolon the turbidity, Fe, Mn, NH3-N, NO2--N and CODMnwere also higher thanfolded-plate reaction pool, and the water turbidity after treated by micro-vortexreaction pool was kept less than3NTU. Under the same conditions, the waterturbidity of folded-plate reaction pool significantly increased (P<0.01) to6.376NTU;the removal efficiency of Fe, Mn and NO2--N obviously decreased (P<0.05).(3) When source water flow was constant, the post-optimality “V”horizontal-tubeprecipitation tank removal rates on the water turbidity and Fe, Mn, NH3-N, NO2--Nand CODMnwere higher than the original inclined-tube precipitation tank. When the source water turbidity increased to138NTU,“V”horizontal-tube precipitation waterturbidity remained below3.0NTU; and the contents of Fe, Mn, NH3-N, NO2--N andCODMnwere also lower than the inclined-tube precipitation tank.(4) When source water flow doubled,“V”horizontal-tube precipitation tank waterturbidity and Fe, Mn, NH3-N, NO2--N, CODMncontent were lower than theinclined-tube precipitation tank, and the water turbidity of the “V”horizontal-tubeprecipitation was kept below3NTU. Under the same conditions, inclined-tubesedimentation tank water turbidity and the contents of Fe, Mn, NO2--N wereobviously increased (P<0.05).(5) The results indicated that there was positive correlation between the inhibition rateof chlorophyll a content in the oxidation of source water Microcystis flos-aquae andthe concentration of ClO2. The inhibition rate of chlorophyll a surpassed51%at1.08mg/L of ClO2. The catalase (CAT) activity increased with increasing ClO2concentrations, and was8.6times of the control at the concentration of1.08mg/L.However, the SOD activity decreased. At the same time, the increasing of lipidperoxidation products and oxidative stress caused the malondialdehyde (MDA)content become abnormal. The research showed that ClO2had inhibiting effect on thegrowth of Microcystis flos-aquae.(6) when the concentration of residual chlorine dioxide in finished water was kept in0.06-0.1mg/L, the concentration of residual chlorine dioxide remained more than0.02mg/L at6km of the water pipe network peripheral; and the total plate count(TPC), total coliforms, thermotolerant coliform bacteria were not detected at factorywater outlet and the terminal of pipe network, this indicated that chlorine dioxide inpipeline had a lasting and stable bactericidal ability. According to the ChineseStandards for Drinking Water Quality,“the concentration of residual chlorine dioxideindex in drinking water should be controlled above0.1mg/L”, but I suggested theconcentration of residual chlorine dioxide can be appropriately reduced, in order toreduce the disinfection by-product ClO2-and decrease the cost of disinfection.