Study On Iron And Manganese Treatment Technology In Micro-polluted Source Water In Northwest Rural Areas

With the increasing water pollution in China,the quality of drinking water is becoming more and more serious.The micro-polluted source water represented by the northwest region faces the situation of excessive iron and manganese.Compared with the more developed cities,iron and manganese in drinking water sources in rural areas in Northwest China often exceed the standard.It is urgent to carry out in-depth research on the removal mechanism of iron and manganese in drinking water sources in the region,and develop new technologies for simultaneous removal of iron and manganese to ensure water supply in the region.Water quality is safe to achieve sustainable development and utilization of drinking water sources.In this paper,the water source in the rural areas of northwest China was selected,and the most economical and practical methods of chemical oxidation,biological method and contact oxidation treatment were selected at home and abroad.The research on the water treatment process and treatment effect was carried out.According to the analysis of the test results,the following main conclusions are drawn:(1)Single factor experiment of degrading iron and manganese in water source water by potassium permanganate,sodium hypochlorite and ozone.The experimental results show the optimal reaction parameters of three oxidants and the removal effect of various oxidants on iron and manganese.Potassium permanganate was the best oxidant in the experimental study.The effect of potassium permanganate pre-oxidation enhanced coagulation to remove iron and manganese in water was optimized by response surface methodology(BBD).The dosage of oxidant and the dosage of coagulant were investigated.The effects of interactions such as pH on the removal of iron and manganese from water by chemical oxidation.The related quadratic polynomial mathematical model was established,and the removal rate of iron and manganese was used as the response value.The optimal reaction conditions were as follows:the dosage of potassium permanganate was 4.2 mg/L,the pH value was 7.5,and the coagulant was cast.When the dosage was 264 mg/L,the removal rates of total iron and manganese in water were 98.22% and 97.49%,respectively.(2)The single factor experiment on the degradation of organic matter and ammonia nitrogen by biofilm method was carried out by different kinds of suspension carriers.The polyurethane foam carrier was found to have better film-hanging effect and had a good effect on microbial adhesion growth.The effects of different operation modes,hydraulic retention time,dissolved oxygen and pH on the degradation of iron and manganese in water source water were investigated by parallel experiments.The experiment was carried out in continuous flow mode and the process parameters were: HRT=8h,DO=4mg /L,the pH is about 7,the removal effect of iron on the reactor can reach 0.2mg/L-0.4mg/L,and theremoval effect on manganese can reach 0.1mg/L-0.3mg/L.And through the screening and identification of microorganisms on the "biofilm" in the reactor,it was found that there were iron-manganese oxidizing bacteria.(3)By changing the influent load in the contact oxidation process to carry out the“film-hanging” experiment,the research results show that the manganese sand is used as the filter material,and the staged lifting influent load method can be used to accelerate the start of the filter,and the filter runs to 42.At the end of the day,the iron and manganese were completed.The effects of different filtration rates,dissolved oxygen and pH on the degradation of iron and manganese in the source water were investigated by single factor experiments.The optimum operating parameters of the filter were: the filtration rate of the filter was 4m/h.The dissolved oxygen concentration in the pool is maintained at about 6 mg/L,and the operating pH is about 7;and the removal of iron and manganese can be accelerated by the method of adding potassium permanganate 4 mg/L within 10 days after the start of the filter.The time is only 25 days.(4)Through the comparison and selection of chemical oxidation,biological method and contact oxidation method to treat iron and manganese in slightly polluted source water in Northwest Rural areas,the combination process of light suspension carrier biofilm method and potassium permanganate oxidation method was selected as the best treatment process;the optimum process parameters of biochemical system were: continuous flow mode operation,HRT=8h,DO=4mg/L,pH about 7,and the optimum engineering of physicochemical system.The process parameters are as follows: the optimum dosage of potassium permanganate is 0.5mg/L-1 mg/L,the optimum pH is 7,the pre-oxidation time is 15 minutes,and the stirring speed is 200 r/min.