Study On The Treatment Of Toxic And Harmful Wastewater Electrocatalytic Oxidation

With the acceleration of the industrialization process,petroleum,fine chemical and other industries have produced a large number of toxic and hazardous wastewater with complex organic species,high concentrations,large emissions,and difficult to degrade,and have carcinogenic,teratogenic and mutagenic effects,which seriously affects environmental safety and people health.At present,conventional wastewater treatment methods have been difficult to meet people's requirements for environmental protection.Electrocatalytic oxidation technology has multiple functions such as redox,air flotation,and flocculation.It also has the advantages of simple operation,small equipment footprint,and avoid secondary pollution.It shows obvious technical advantages in advanced wastewater treatment.Two widely used additives in the fine chemical industry were selected:Nekal BX and Benzotriazole(BTA).Based on the reaction conditions such as current,pH,electrolyte dosing amount and number of plates were examined,the COD removal rate,energy consumption per ton of water and COD per unit mass,and the degradation mechanism of multi-plates electrocatalytic oxidation technology on treating two kinds of simulated wastewater were studied.Multi-plate electrocatalytic oxidation technology was used to treat Nekal BX simulated wastewater with 500 mg/L concentration.Under the optimum experimental conditions,the COD removal rate is 80.23%,the energy consumption per ton of water is 1.722 kW·h/m3,and the energy consumption per unit mass COD can reach 2.21 kW·h/(kgCOD).To treat benzotriazole simulated wastewater with 800 mg/L concentration the COD removal rate can reach more than 90%,the energy consumption per ton of water is 1.2075 kW·h/m3,and the energy consumption of unit mass COD is stable at 0.893 kW·h/(kgCOD).The removal rate of COD can reach 50%and the removal rate of BX is stable at 78%in the actual wastewater treatment of Nekal BX from a petrochemical plant in Lanzhou.After combined with ozone catalytic oxidation technology,COD drops below 50 mg/L and unzipped powder BX also drops below 10 mg/L,which meets the emission standards.It is proved that electrocatalytic oxidation technology has the potential for industrial application in the treatment of practical wastewater.The study of multi-electrode plate electrocatalytic oxidation technology for treating toxic and harmful simulated wastewater shows that under certain reaction conditions,the number of plates has a great influence on the treatment effect of pollutants and energy consumption.When the number of plates increased from 2 to 6,the COD removal rate increased from 21.44%to 80.23%,and the energy consumption per unit of COD decreased from 12.3 kW·h/(kgCOD)to 2.21 kW·h/(kgCOD),energy consumption per ton of water decreased from 2.81 kW·h/m3 to 1.89 kW·h/m3.Therefore,by increasing the number of plates,both the processing effect can be improved and the energy consumption can be reduced.The mechanism research on the treatment of toxic and harmful wastewater by multi-electrode electrocatalytic oxidation technology shows that the treatment of wastewater by electrocatalytic oxidation technology is the result of the combined action of electrochemical oxidation reduction,metal ion flocculation and electric floatation,of which the contribution rate of electric floatation is about 9.5%.Through the change of pH in the reaction process,it is found that chloride ion has a great influence on the degradation effect.