The Treatment Of Wastewater Containing Complexing Copper And Nickel By Electrofenton Method

Complexing heavy metal in electroplating wastewater is the key point in treating this kind of wastewater,and the key to effectively removing complexing heavy metals is breaking down the complex.The way of fenton oxidation to break down complex has been generally used to deal with such wastewater nowadadys,which has disadvantages such as large production of sludge,long residence time and low utilization rate of medicament.Compared with the traditional fenton reaction,the electro-fenton method has obvious advantages of high utilization rate of H₂O₂ and Fe²⁺,and less sludge production,which can effectively handle electroplating waste water containing complexing heavy metal,thus avoiding shortcomings of the traditional fenton process.The selection of electrode material plays a crucial role in electric fenton.Although many related research results have come out,electrode materials got from such researched remain hard to prepare and still are of high price,difficult to practical application.This research will take iron,aluminum and graphite as the research objects,which are easily accessible from markets and of lower prices.Then treatment effects the three electrode materials have on C u-EDTA and N i-EDTA wastewater in electro-fenton methods by contrast tests are observed in order to determine the optimal electrode materials for practical engineering,combined with the processing cost.Based on these processes,I optimize electricity fenton process though bench-scale laboratory tests and determine the suitable conditions of the process parameters by the pilot run.Through bench-scale laboratory tests,I investigate on the main factors of handling the complexing copper and nickel wastewater in electrode fenton methods when iron,aluminum and graphite are used as electrode materials respectively,and make a comprehensive comparison about the process effects and costs of the three electrode materials under their own optimal conditions.The results show that electro-fenton methods of the three kinds of electrode materials all have good removal effects on Ni-EDTA and C u-EDTA simulation wastewater.After the comprehensive comparison,the iron electrode is optimal.The electrode-Fenton method of the iron electrode material in conditions of initial p H value of 2.0,current density of 20 mA/cm² and hydrogen peroxide dosing quantity of 6 mL/L·h,can remove 98.54% of N i and 99.8% of Cu,respectively,and the comprehensive cost is 12.75 yuan/tons of water.Optimal experiment parameters were used for processing the C u/N i-EDTA wastewater in the sacrificial iron-anode electro-Fenton method to study the effect of temperature,initial concentration.Experimental results show that the iron electrode material achieve a good removal efficiency of heavy metals when the electrode gap is 2 cm,current density is 20 mA/cm²,and hydrogen peroxide dosing quantity is 6 mL/L·h by continuous dosing.The existence of C l-is beneficial for electrode-fenton reaction,but citric acid and hypophosphite ha ve inhibitory effects on the electrode-Fenton method of the iron electrode material.When using the electrode-Fenton method of the iron electrode material handling C u/N i-EDTA simulation wastewater,the removals of Ni and C u are mainly by flocculation settling after breaking down complex and separating precipitation of hydroxide made from metal ion and additive of OH-from water.In addition,a small amount of metal ion is removed by being adsorbed to electrode-plate with the current migration.As for the actual wastewater,determined optimal operation parameters of electrode-Fenton process under the concentration of complexing heavy metal effluents ranging from 2 to 30 mg/L.Main operation parameters of electrode-Fenton process are as follows: residence time of 0.5-1 h,hydrogen peroxide dosing quantity of 3.4-8.5 mL/L·h,current density 20-30 mA/cm².In these conditions,C u and N i can be stably discharged with living up to standards,under which,COD and TP can also be removed to some extent.