Research On Pretreatment Of Electroplating Wastewater By Micro Electrolysis-fenton Combined Process

In recent years, the development of manufacturing industry in China is very rapid.As these industries cannot do without the electroplating industry, such as automobiles,machinery, aerospace, construction and so on. The electroplating industry is related topeople's livelihood. The electroplating process will produce large amounts of acid,alkali, organic matter and heavy metal ions. These pollutants will release into theenvironment with the discharge of electroplating wastewater. This phenomenon willhave a great threat to the environment and human health. The electroplatingindustry wastewater contains not only heavy metals but also refractory organics. Theelectroplating wastewater cannot into the biochemical process directly withoutpretreatment. Most of the current electroplating factrories use the traditionalchemical process as a pretreatment process. The heavy metal removal effect is poorwhen the wastewater is treated by traditional chemical precipitation process. Therequired chemicals cost high and it will produce large amounts of sludge. Therefore, itneeds a method which can treat organic complexation of heavy metals efficiently.This paper presents micro electrolysis-Fenton combined pretreatment process,which study to the comprehensive wastewater in electroplating industry as the researchobject. First, the wasterwater was treated by micro-electrolysis and Fenton respectively.The best technological conditions of micro-electrolysis and the Fenton were optimized.These studies results the effects of the treatment of electroplating wastewater. Themechanism of micro electrolysis was also studied. Micro electrolysis Fenton continuousflow process was established, if it has a stable treatment effect.Through the micro-electrolysis static test, under these conditions: iron carbon ratioof1:1, pH=3, reaction time30min,0.2m3/h of aeration, the effects of microelectrolysis is best. The COD removal rate reached60.31%, the copper removal ratewas98.37%in copper containing wastewater, and the biodegradability of thewastewater is improved from0.1to0.43; for the zinc containing wastewater, the CODremoval rate was59.06%and the zinc removal rate was98.35%, the biodegradability ofthe wastewater is improved from0.09to0.24. The surface analysis of the microelectrolysis fillerand and flocs was studied, the main mechanisms of micro-electrolysisare oxidation reaction and adsorption and flocculation of iron filings. Fenton static test results show that: H2O2of dosing ratio was3‰, the dosage of0.1mol/LFeSO4was1.5mL, pH value is4, reaction time is30min. Under theseconditions, the effects of Fenton process in electroplating wastewater treatment arebest. In the case of copper containing wastewater, after the Fenton reaction, the removalrate of COD is78.22%, the biodegradability of the wastewater is improved from0.24to0.57.On the basis of previous research, the micro-electrolysis-Fenton continuous testwas studied. When iron filings and activated carbon as filler, the stability of treatmenteffects of the electroplating wastewater is poor. The removal rate of copper andCOD decreased rapidly. It shows that in practical engineering, We need regularreplacement of packing or filling of regeneration treatment.