Flocculation Treatment And Resource Utilization Of Polluted Water In Zipeng Mountain Area

With the initial success of urban sewage treatment,rural sewage treatment has become one of the most important tasks in the construction of new countryside.The Zipeng Mountain area is an important water source for the Pai River,the main tributary of Chaohu Lake.And it is closely related to the safety of water quality of the Pai River and the"Diversion from the Yangtze River to the Huaihe River"project.Due to the local special topography and natural conditions,pollutants overflowed in the ponds during the rainy season,which seriously affected the safety of water quality of the Pai River.Therefore,low-cost,reusable and non-secondary pollution sewage treatment method was urgently needed to treat local polluted water bodies.In this paper,sewage in Zipeng Mountain area was the research object.A new type of composite magnetic flocculant mCTS@（PGA-Fe₃O₄）was prepared,which uses magnetic nano Fe₃O₄ particles,gallic acid,and chitosan as raw materials.The preparation conditions of mCTS@（PGA-Fe₃O₄）were optimized and characterized.The external factors affecting the flocculation effect of mCTS@（PGA-Fe₃O₄）were explored through simulated wastewater experiments.The flocculation conditions of mCTS@（PGA-Fe₃O₄）were optimized by response surface analysis.The economic,social and environmental benefits of sewage resource utilization in Zipeng Mountain area were analyzed and prospected.The main results and conclusions are as follows:（1）The single factor experiment results showed that the optimum preparation conditions of mCTS@（PGA-Fe₃O₄）were:the dosage of GA,AM,and trigger mass were 0.3 g,3 g,and0.03 g,respectively;the modified temperature of Fe₃O₄ and polymerization were 60℃.Under the optimal preparation conditions,the removal rates of turbidity,chromaticity,and COD can reach 91.5%,84.2%,and 79.6%,respectively.Through characterization and analysis of SEM,FT-IR,XRD,Zeta potential,the successful synthesis of mCTS@（PGA-Fe₃O₄）was confirmed,and the introduction of AM and Fe₃O₄ enhanced the Zeta potential of mCTS@（PGA-Fe₃O₄）to 16.72 m V,much higher than the 2.35 m V of mCTS.（2）The results of simulated wastewater experiments showed that the pH value was between 7 and 9,the temperature was 25℃,the stirring time was controlled at 5 min,and the settling time was controlled at 10 min.At that time,mCTS@（PGA-Fe₃O₄）had the best flocculation effect.At this time,the removal rate of turbidity and COD could reach 95.2%and81.2%.By combining mCTS,PAM,and PAC,two composite systems of mCTS3-PAM and mCTS4-PAC were obtained.It was found that the removal rates of turbidity and COD were the highest（84.2%and 76.1%）,which were still lower than the mCTS@（PGA-Fe₃O₄）treatment compound simulation.It also showed that mCTS@（PGA-Fe₃O₄）has better flocculate performance.（3）The flocculation effects of three composite flocculants（mCTS@（PGA-Fe₃O₄）,mCTS3-PAM and mCTS4-PAC）were compared.The CCD response surface method was used to optimize mCTS@（PGA-Fe₃O₄）flocculation conditions,and the recycling experiments were carried out.The results showed that:mCTS@（PGA-Fe₃O₄）>mCTS3-PAM>mCTS4-PAC.When the dosage of mCTS@（PGA-Fe₃O₄）was 0.3 g/L,the removal rates of turbidity,chroma and COD were the highest.The removal rates were 90.2%,82.3%,and 76.4% respectively.The results of response surface experiments determined that the optimal flocculation conditions for mCTS@（PGA-Fe₃O₄）were:dosage（0.38 g/L）,pH（7.42）,temperature（25.2℃）.Under these conditions,the removal rate of turbidity,chroma,and COD were 92.0%,84.2%,and 79.9%,respectively.The average moisture content of the flocs produced by mCTS@（PGA-Fe₃O₄）flocculation was 75.2%,which was far lower than the conventional level.The results of recycling experiment showed that the recovery rate of mCTS@（PGA-Fe₃O₄）could reach 85%after each flocculation,and the total recovery rate was 68.9%,indicating that mCTS@（PGA-Fe₃O₄）had a certain application prospect in sewage treatment in Zipeng Mountain area.（4）A set of suitable for Zipeng Mountain sewage treatment process was drawn up and a benefit analysis was carried out.The results showed that with the cost of 272400 yuan,the annual income is 213100 yuan.It could start to make profits in more than a year,with good economic,social and environmental benefits.Sewage can be used as liquid fertilizer after flocculation treatment,and dewatered sludge can be reused in farmland through fertilizer treatment to turn harm into benefit.