Study On Treatment And Reuse Of Laundry Wastewater By Electrocoagulation-Ozone

With the booming development of the home appliance industry and the rinsing of people's living standards,washing machines have become the most common household appliances,becoming a powerful tool to liberate people's hands.However,while washing machines bring convenience to people,they also generate a lot of laundry waste water during their use.The direct discharge of laundry wastewater without targeted treatment and reuse can cause serious harm to aquatic plants,animals and ecosystems,as well as waste of water resources.Therefore,it is necessary to treat and reuse laundry wastewater to reduce pollutant discharge and save water resources.Firstly,electrocoagulation and ozone oxidation technologies were used to treat laundry wastewater.The reaction process and influencing factors on the removal of pollutants from laundry wastewater were investigated,and the optimal process parameters were determined.On this basis,we further investigated the effect of electrocoagulation-ozone on the removal of pollutants in laundry wastewater under different process conditions,and analyzed the relationship between electrocoagulation and ozone oxidation in the whole reaction process by comparing the changes of COD,linear alkylbenzene sulfonate?LAS?and turbidity in laundry wastewater treated by electrocoagulation,ozone oxidation and electrocoagulation-ozone,respectivity.Finally,the morphological structure and elemental composition of the flocs formed during the various reactions,as well as the variation of contaminants in the water before and after treatment,were analyzed to reveal the mechanism of removal of contaminants from the laundry wastewater during the entire reaction process.The main conclusions are as follows:?1?In the experimental process of laundry wastewater treated by electrocoagulation technology,the COD removal rate was 83%,LAS removal rate was 87%,turbidity removal rate was 91%,COD was 90.7 mg/L,LAS was 5.97 mg/L and turbidity was 10.3 NTU in the treated water after 25min reaction under the conditions of anodized stainless steel plate and aluminum plate ratio of 1:1,current density was 5 mA/cm²,initial pH was 5 and the distance between the plates was 2 cm.The quality of treated water does not meet the water quality standards for domestic miscellaneous water GB/T 18920-2002.?2?In the experimental process of laundry wastewater treated by ozone oxidation,the COD removal rate was 53%,LAS removal rate was 68%,turbidity removal rate was 50%,COD was 250.8 mg/L,LAS was 14.7 mg/L and turbidity was57.2 NTU in the treated water after 25 min at an initial pH of 9 and ozone concentration of 73 mg/L.The quality of treated water does not meet the water quality standards for domestic miscellaneous water GB/T 18920-2002.?3?In the experimental process of treatment and reuse of laundry wastewater by electrocoagulation-ozone,the COD removal rate in laundry wastewater was as high as 97%,LAS removal rate was as high as 99%and turbidity removal rate was as high as 99%after 20 min of reaction at a current density of 4 mA/cm²,initial pH 7,plate distance of 2 cm and ozone concentration of 73 mg/L.Compared with electrocoagulation and ozone oxidation technologies for laundry wastewater,the COD removal rate was increased by 14%and 35%,LAS removal rate was increased by 12%and 31%,and turbidity removal rate was increased by 8%and 49%,respectively.This indirectly confirms that there is a synergy between electrocoagulation and ozone oxidation in the whole reaction system,the reaction of anodic electrolysis of Fe²⁺and O₃ in the reaction system to produce a large number of strongly oxidizing·OH could completely mineralize organic pollutants,greatly improving the removal rate of pollutants,after treatment water COD is 16.0 mg/L,LAS is 0.45 mg/L,turbidity is 1.1NTU,after treatment water quality to meet the domestic water quality standards GB/T18920-2002.?4?The results of FT-IR and SEM-EDS analysis of the flocs under the above reaction conditions indicate that the flocs are composed of O,Fe,Al and other major elements,including iron oxide,aluminum oxide,aluminum hydroxide and iron hydroxide,with different particle sizes and different morphological distribution.In addition,the UV-Vis and GC-MS analyses of the effluent before and after treatment showed that 55 organic pollutants were detected in the laundry effluent and the organic matter species and abundance decreased significantly after different treatment processes.After electrocoagulation and ozone treatment system,22 and 36 organic substances were detected in the effluent,and most of the long-chain alkanes,olefins,ethers and aldehydes were completely removed;after electrocoagulation-ozone treatment,only 18 residual organic substances were detected in the effluent,mainly small molecular inorganic acids such as acetic acid and butyric acid.