Application Of Electrocoagulation Technology In Rapid Treatment Of Initial Rainwater

The initial rainwater runoff pollution is one of the most important pollution sources in the non-point source pollution.The initial rainwater composition is relatively complex,the concentration of SS,COD and other pollutants is high,and the biodegradability is poor.Specialized in dealing with the related process of initial rainwater.In this study,the characteristics of the initial rainwater quality were analyzed through a large number of literature research and field research,and the electroflocculation process was proposed as the main process for rapid treatment of the initial rainwater.Therefore,this study will carry out research from three aspects: the selection of the optimal value of the parameters,the selection of the optimal flow state,and the Chinese-style continuous operation experiment.First,through single-factor experiment and multi-factor experiment,multiple experimental parameters of the electroflocculation process were studied in depth.The results showed that when the electroflocculation process alone treated the simulated initial rainwater,the anode material was aluminum-zinc alloy,the reaction time was 30 min,and the precipitation time was 30 min.When the electrode connection method is unipolar parallel connection,the distance between the electrode plates is 2cm,the number of electrode plates is8,and the current density is 40A/m2,the electroflocculation process achieves the best operating state in terms of pollutant removal effect and operating energy consumption.The removal rates of SS,COD and TP were 91.25%,84.38% and 99.68%,respectively.The concentrations of pollutants after treatment were SS26.43mg/L,COD41.40mg/L and TP0.02mg/L,respectively.In addition,the two parameters of reaction time and current density have a very significant effect on the pollutant removal rate,which can be used as the main control parameters in practical engineering design and operation.On the basis of determining the optimal operating parameters,two flow regimes,parallel perforated flow and staggered perforated flow,were set up.The COMSOL software was used to simulate the flow regime,and the experimental results were used for verification and analysis to determine the optimum flow regime.The results show that under the dislocation perforation flow state,the turbulent flow effect of the fluid is stronger,which is beneficial to the diffusion of metal ions and the contact reaction with pollutants.The removal rates of SS,COD and TP are 94.00%,81.95% and 98.97%,respectively.And by adding a filtration process after the electroflocculation process,the operating energy consumption of the electroflocculation stage can be effectively reduced,and the final removal rate of each pollutant is also higher than that when the electroflocculation process is used alone.Under the combined process of electroflocculation and filtration,the removal rates of SS,COD and TP were 94.33%,84.70% and 98.45%,respectively,and the concentrations of pollutants after treatment were SS18.00mg/L and COD31.29 mg,and TP0.02mg/L.By building a medium-sized experimental device for the electro-flocculation-filtration process for a long-term continuous operation experiment,the results show that the overall operation of the medium-sized device is relatively stable and can be operated for a long time in the rainy season.The final removal rates of SS,COD and TP reached 95.00%,89.47% and98.33%,respectively.The concentrations of pollutants after treatment were SS17.00mg/L,COD21.50mg/L and TP0.21mg/L,respectively.In terms of energy consumption,the electricity consumption per ton of water in the electroflocculation stage is 0.57 k Wh,and the economical operation cost is low,which has large-scale engineering application value.