Study On Treatment Technology Of Raw Water Contaminated By Straw Impregnation

At present,the research on the treatment technology of high-color organic polluted water sources is mainly aimed at humus water on the catchment basin of natural water sources,and the pollutants are mainly decaying materials of vegetation in deep forests in mountainous areas.The water treatment technologies adopted include biological contact oxidation,activated carbon adsorption,enhanced coagulation precipitation,enhanced filtration,etc.However,every water source has regional characteristics,and the existing treatment technology needs to be applied in different areas,in order to find the technical method suitable for the characteristics of local water quality.This study takes the treatment technology of high color organic contaminant water from natural water source as the starting point,studies and analyzes the water pollution situation in Lixia River area,and researches and innovates the unit water treatment technology for the high color organic contaminant raw water formed after pollution,aiming at the situation of surface water polluted by straw impregnation solution caused by random discarding of agricultural straw and returning water to fields.The combined technology of water treatment is formed according to the characteristics of water quality.The main contents and achievements of this research are as follows:(1)The organic matter analysis of raw water samples contaminated by straw dipping solution was carried out.Through the infrared spectrum scanning of straw soaked water samples of rice,wheat and rape,comparing with the attribution table of characteristic peaks of the three kinds of straw,it is found that most of the characteristic peaks of the three kinds of straw belong to the same,only a few groups are different.The results show that the main pollutants in the three water samples are humic acid,fulvic acid,aliphatic compounds,carbohydrates,alcohols,phenols and aldehydes.(2)The pretreatment technology of raw water polluted by organic straw with high color was studied.Through the biological contact oxidation experiment,it is determined that the biological contact oxidation unit adopts the combined biological filler,and the optimal hydraulic retention time HRT is 2h.In the dynamic treatment experiment,the average removal efficiency of raw water ammonia nitrogen can reach 52.18%,the average removal rate of CODMn is 13.51%,and the average removal rate of TN is 14.03%.By adding oxidants such as potassium permanganate,sodium hypochlorite and ozone,the dosage parameters of three chemical preoxidation agents were determined as KMnO4(1.4mg/L,50min),NaClO(1.8mg/L,50min)and O3(2.0mg/L,8min).The removal efficiencies of CODMn and chroma in raw water were 57.14%and 23.78%,48.57%and 24.39%,and 70.53%and 33.12%,respectively.The dosage of powdered activated carbon preadsorption was 30mg/L and the adsorption time was 60min.The removal rates of chroma and CODMn were 54.85%and 63.82%,respectively.(3)The conventional physicochemical treatment technology for raw water contaminated by high color organic straw was studied.The best coagulant dosage was 20mg/L,and the removal rates of CODMn and chroma were 44.4%and 57.14%,respectively.;The optimal dosage of PAM is 1.0mg/L,and the removal rates of CODMn and chroma are 55%and 60.95%,which are 10.56%and 3.81%higher than that of aluminum sulfate alone.;Through the filter test of sand filter device,it is determined that the sand filter speed is 6m/h,and the water quality of the filtered water sample is improved compared with that of the precipitated water.According to the experiment of granular activated carbon filtration,the filtration rate of carbon filtration is 8m/h,and the effect of granular activated carbon filtration is better than that of sand filtration.The disinfection dose was determined to be 1mg/L through the sodium hypochlorite disinfection experiment.The disinfection process further degraded the residual CODMn and chroma residual values in the water body which were far lower than the drinking water quality standard.The disinfection procedure benefited from the effect of the chemical preoxidation process,which reduced the use of disinfection dose and made it more economical.(4)The study analyzed the treatment effect of the combined process on raw water,which can reduce the chromaticity of raw water from 105 degrees to about 1-2 degrees,and the average removal rate is about 98.87%.Reduce CODMn from 15mg/L to 0.3～0.6mg/L,with an average removal rate of 95.56%.The average removal rate of ammonia nitrogen from 1.5mg/L to 0.08-0.12mg/L is 92.55%,and the turbidity can be reduced from 34NTU to around 0.2～0.6NTU,with an average removal rate of 98.45%.The average removal rate of UV254 can reach 88.05%.