Experimental Study On Treatment Of Drilling Wastewater By Three - Dimensional Electrode Method

Three-dimensional electrode method was used to treat drilling wastewater which came from northwest of Sichuan. The experiment researched the more effect and lower energy consumption with three-dimension electrode method of different power source between pulse power supply and DC electrical source. The experiment also studied the representative parameters that impacted on the test results, and analysis the reason which affected the removal rate of CODcr through the experimental data and the experimental phenomenon by changing the value of the single factor as initial concentration of CODcr, electrical current, initial pH and electrolysis time. The orthogonal experiment was carried on basing on the single factor experiment, and the best reaction condition had been determined. After the pulse power supply was chosen as the reactive power of the three-dimensional electrode, Fenton had been combined with it by its characteristic that can be combined with other technique easily. It had been determined the optimal reaction conditions and the actual processing efficiency under this condition according of the results of the orthogonal experiment.The experimental results showed that the technology for drilling wastewater had good effect by three-dimensional electrode. Through the acidification-neutralization-coagulation-three-dimensional electrode by pulse power+Fenton method process, the CODcr value could be reduced from the initial of12961mg/L to51.30mg/L after treatment and reached the discharge standard. Acidic condition was preferred to neutral and alkaline condition in the results of electrolysis reaction. When pH=2, the chloride ion which in the drilling waste water converted to active intermediates HOCl by electrochemical reaction. It could be strengthened the oxydic reaction process, and decreased of chloride ion concentration as well. Drilling wastewater removal rate increases with the strength of the current rise first and then decreased, The rising trend became to slowly of the removal rate of CODcr by the electrolytic time increasing. Under the optimum conditions:the initial CODcr concentration=1500mg/L, initial pH=2,electrolytic current=2A, electrolysis time=40min. The removal ratio of CODcr could reach69.8%by three-dimensional electrode with DC power supply, and the CODcr removal ratio was67.9%by the other one reaction system with pulse electrical source. Through the contrast experiment, the pulse power supply was chosen as the reactive power of the three-dimensional electrode, and Fenton had been combination of it. Considering the effects of different factors such as initial CODcr values of the waste water, pH value, duty cycle, electrical current, Fe2+/H2O2, electrolysis time and impulse frequency, The best factor combination determined by orthogonal experiment of the three-dimensional electrode with pulse power supply+Fenton was impulse frequency=1800Hz, duty cycle=0.4, electrical current=2A, electrolysis time=40min, initial CODcr=1200mg/L, pH value=3, n(Fe2+)/n(H2O2)=0.2. Under the optimum conditions, The removal ratio of CODcr could reach97.5%.