A novel advanced oxidation process—wet electro-catalytic oxidation for high concentrated organic wastewater treatment

Abstract

A novel advanced oxidation process --wet electrocatalytic oxidation (WEO) was studied with p-nitrophenol as model pollutant and β-PbO 2 electrode as the anode. Compared with the effect of the individual wet air oxidation (WAO) and electrochemical oxidation (EO), the effect of WEO showed synergistic effect on COD removal under the conditions of temperature 160℃, C=1000 mg·L −1 , P N 2 =0.50 MPa, P O 2 =0.9 MPa, current density = 3 mA·cm −2 , Na 2 SO 4 3 g·L −1 . And the synergistic factor got the best value of 0.98 within 120 min after 180 min treatment. The synergistic factor was studied after 120 min treatment at 100℃, 120℃, 140℃ and 160℃, and the effect of 120℃ was the best with the value of 1.26. Possible mechanism for the synergistic effect was discussed based on the analysis of free-radical generation and intermediates detected by HPLC and GC/MS. wet air oxidation, electrochemical oxidation, wet electrocatalytic oxidation, synergistic effectThe wastewater containing high concentrated aromatic compounds cannot be treated effectively by conventional biological or physical-chemical treatment due to their structure stability, bio-resistance and strong toxicity. It has been one of the key technical difficulties in wastewater treatment for a long time in China. At present, wet air oxidation (WAO) and electrochemical oxidation (EO) are two ways dealing with organic wastewater [1][2][3][4][5] .WAO is an effective method dealing with many types of high concentrated organic wastewaters with some equipments application in industry [1,2] , but the application of this process is limited for the harsh operational conditions of high temperature and high pressure [1,6] . Recently, catalytic wet air oxidation (CWAO) is extensively studied to lower the operational conditions and some improvements have been achieved. But the introduction of catalysts, the applicability and toxicity of the catalysts should be carefully considered [7] . So, CWAO is still far from solution due to the second pollution and the declination of treatment efficiency. Sound processes with less rigorous operational conditions, being more efficient for high-concentrated organic wastewater treatments without second pollution are urgently required.Electrochemical oxidation (EO) is a newly advanced oxidation process and has been one of the key technologies of wastewater treatment for its high efficiency, being friendly to environment and easy facility. But present researches showed that it could only work well to the organic wastewater of low concentrated and less efficiency to that of high concentrated [8,9] .Based on the review of these two technologies, this paper tries to combine the advantages of WAO and EO at relative moderate conditions, and uses wet electro-

The Bimetallic Synergistic Effect in Heterogeneous UV/Fenton System for the Treatment of Refractory 6-Nitryl Wastewater

“…The treatment of organic wastewater is a difficult problem due to its high concentration, poor biodegradability and toxicity [7][8][9]. The combination of UV and the homogeneous Fenton reagent will increase the decomposition rate of hydrogen peroxide, enhancing oxidation capacity.…”

Study on dynamics characteristics of wet air oxidation of non-ionic surfactants

“…A lot of research work indicated [5,6] that wet air oxidation was mostly suitable for wastewater treatment of the high-strength refractory organic wastewater or toxic and dangerous effluent. Presently, the studies on wet air oxidation go deeply into the reaction mechanism and kinetics of prime matter, and furthermore, develop in the directions of catalytic wet air oxidation (CWAO) [7,8] and supercritical wet air oxidation (SWAO) [5] .…”

非离子表面活性剂的湿式氧化动力学

“…明 [1~4] , 湿式氧化(wet air oxidation, WAO)对乳化液废 水具有较高有机物去除率, 并显著提高出水的可生 化性, 是有效的处理技术. 众多研究表明 [5,6] , 湿式氧 化特别适于高浓度难降解或有毒有害废水的处理, 目前的研究已深入到纯物质的反应机理及动力学, 并 向 催 化 湿 式 氧 化 [7,8] (catalytic wet air oxidation, CWAO) 和 超 临 界 湿 式 氧 化 [5]…”