Drilling Wastewater Treatment Based On Three - Dimensional Electrode Method

A large number of drilling wastewater was generated in the development of the gas and oil industry. It contained a lot of oil, heavy ions, refractory organic compounds, chloride and other toxic and harmful substances. Direct discharge of drilling wastewater into the environment without any treatment progress would cause a serious harmful impact on human life and production. In this paper, drilling wastewater from MOXI was treated with coagulation+three-dimensional electrode technology for treatment. In order to further strengthen the treatment efficiency, Fenton’s reagent was injected in three-dimensional system. The optimal coagulants and coagulation conditions were explored. In addition, activated carbon fiber (ACF) used as third pole material of three-dimensional electrodes system were investigated to explore the treatment efficiency. The optimum process conditions of treating drilling wastewater with three-dimensional electrode technology was analyzed as well as optimization of experimental conditions and treatment efficiency were investigated after joining Fenton’s reagent.The aluminum sulfate was selected as an optimal coagulant and nonionic polyacrylamide was selected as an optimal assistant-coagulate through a serious of coagulation experiments. The optimal coagulation conditions were as follows:pH value was9, aluminum sulfate dosage was9g/L, nonionic polyacrylamide dosage was10mg/L. Under these optimal conditions, CODCr removal rate was65.4%and the decolorization rate was90%. The treatment efficiency of activate carbon fiber and granular activated carbon (GAC) as adsorbent and third electrode material of three-dimensional electrode system was compared respectively. It indicated that ACF was better than GAC to be third electrode material. The optimal conditions of orthogonal experiment about the treatment of drilling wastewater with ACF three-dimensional electrode technology as follows:initial CODCr was1000mg/L, pH value was5, current density was31.8mA/cm2, aeration quantity was0.8L/min, electrolytic time was60min. Under these optimal conditions, CODCr removal rate was40.3%. ACF three-dimensional electrode technology which degraded the CODCr of drilling wastewater obeyed the apparent first order reaction kinetics, the kinetic equation was: CODCr=C0*e-(0.00834t+0.00585). The optimum operators of three-dimensional electrode method with Fenton’s reagents treating drilling wastewater were c(H2O2)/c(Fe2+)=13.6, Fenton’s reagent dosage (c(H2O2)+c(Fe2+))70.1mmol/L, under this condition, CODCr removal rate was72.5%as well as TOC removal rate was72.5%. Three-dimensional electrode-Fenton’s reagent technology which degraded the CODCr of drilling wastewater obeyed the apparent first order reaction kinetics, the kinetic equation was:CODCr=C0*e-(0.01984t+0.01468).