The Study On Treatment Of Refractory Organics In Water By Microelectrolysis Coupled Flocculation

With the rapid development of modern industry,the pollution range and severity of difficult to degrade organic compounds are wide,and their types and production are increasing day by day,becoming a key and difficult point in current water treatment.Improper treatment of refractory organic compounds in wastewater can result in long-term residues in the natural environment,posing a serious threat to the ecological environment and human health.In response to the problems of high chromaticity and poor biodegradability of difficult to degrade organic compounds,this study adopts iron carbon micro electric decoupling flocculation and aluminum carbon micro electric decoupling flocculation methods,with printing and dyeing wastewater,pesticide wastewater,and antibiotic wastewater as target pollutants.The main research methods are as follows:single factor experiment is used to investigate the influence range and ORP（oxidation reduction potential）change of four factors,namely flocculation p H,flocculation mixing time,flocculation mixing speed and standing time,on the treatment of three kinds of refractory organic wastewater by micro electric decoupling and flocculation under the best conditions of micro electrolysis.On this basis,orthogonal experiment and micro electrolysis and flocculation synergy experiment are designed to obtain the best reaction conditions.Through fractal dimension,FTIR,UV-vis,and Ferron timed complex colorimetric method were used to analyze the removal mechanism of micro electric decoupling flocculation method for refractory organic wastewater.The experimental results show that the removal rate of alkaline red simulated wastewater by the iron carbon micro electric decoupling and flocculation method under optimal conditions can reach 92.43%,with flocculation removal accounting for 32.15%;The removal rates of benzene,naphthalene,and nitro pollutants in pesticide wastewater are 52.18%,98.44%,and98.45%,respectively.The flocculation removal effect accounts for 37.63%,35.01%,and 40.76%respectively;The removal rate of tetracycline hydrochloride simulated wastewater is 92.30%,with flocculation removal accounting for 28.55%.Under the optimal conditions,the removal rate of alkaline red simulated wastewater by aluminum carbon micro electric decoupling and flocculation method can reach 97.88%,with flocculation removal accounting for 29.69%;The removal rates of benzene,naphthalene,and nitro pollutants in pesticide wastewater are 58.76%,99.53%,and 99.67%respectively.The flocculation removal effect accounts for 35.44%,28.75%,and 21.23%respectively;The removal rate of tetracycline hydrochloride simulated wastewater is 98.43%,with flocculation removal accounting for 21.64.Compared to the iron carbon micro electric decoupling and flocculation method,the aluminum carbon micro electric decoupling and flocculation method has a better removal effect of organic pollutants.The trend of ORP change during the reaction process is significantly negatively correlated with the change in removal rate.The higher the removal rate,the lower the ORP,which means the lower the oxidation resistance of the solution.The fractal dimension of the flocs after the reaction was studied.The results showed that the fractal dimension of the flocs generated from the treatment of printing and dyeing wastewater,pesticide wastewater and antibiotic wastewater by iron carbon micro electric decoupling flocculation was 1.1857,1.1959 and 1.1,respectively;The fractal dimension of flocs generated from printing and dyeing wastewater,pesticide wastewater and antibiotic wastewater treated by Al-C system are 1.2279,1.2684 and 1.1709 respectively.Compared with Fe-C system,Al-C system has larger floc fractal dimension,more compact floc structure,smaller porosity,more concentrated particle size distribution,and more prone to adsorption,net capture and sweeping.Through the Fourier transform infrared spectroscopy before and after the reaction,as well as the infrared spectroscopy of the flocs after the reaction,and the changes in UV visible absorption spectroscopy during the reaction process,it was found that the organic structures containing N=N,N-X,[NO₃]^-,C-O,N-O in the refractory organic wastewater were damaged to some extent,leading to bond breakage.However,organic compounds containing structures such as naphthalene ring and tetraphenyl can only be degraded into multiple benzene ring structures,as they cannot be fully mineralized by micro electrolysis,Mainly removed through floc adsorption.After the reaction,the Ferron timing colorimetric curve of the floc solution was obtained,and the relative percentage content of different chemical forms of Al in the tested floc solution was calculated.It can be seen that in the floc solution obtained from the treatment of alkaline red simulated wastewater,pesticide wastewater,and tetracycline hydrochloride simulated wastewater by micro electric decoupling flocculation,the low degree of polymerization forms of aluminum monomer and Al₂-Al₃ accounted for 81.5%,71.33%,and 71.43%,respectively,while the moderate polymerization forms such as Al13 accounted for 18.5%,28.67%,and28.57%,respectively;There is no high polymer form of Al in the three types of floc solutions.This study demonstrates the effectiveness of the micro electro decoupling flocculation method for the treatment of refractory organic wastewater without the need for additional flocculants.By providing easy access to raw materials and simple operating steps,the efficiency of the micro electrolysis reaction is improved,and the problem of metal ions(Fe²⁺,Fe³⁺,Al³⁺)entering the solution after the micro electrolysis reaction is solved,further leveraging the advantages of the micro electrolysis method of"treating waste with waste".