Advanced treatment of biologically pretreated coking wastewater by electrochemical oxidation using Ti/RuO₂–IrO₂ electrodes

Abstract

BACKGROUND: Electrochemical oxidation has attracted wide attention in wastewater treatment because of its strong oxidation performance and ease of control. This work investigated the feasibility of electrochemical treatment using a Ti/RuO 2 -IrO 2 anode as an advanced treatment of coking wastewater. The influential operating factors including current density (9.6-108.2 mA cm −2 ) and electrode gap (0.5-2.5 cm) were evaluated. RESULTS: The current density and electrodes gap had significant effects on COD and NH4 + -N removal and the energy consumption. The degradation of COD and NH 4 + -N followed pseudo-first-order kinetics. In most experiments, high levels of NH 4 + -N removal (NH 4 + -N removal ratio > 95%) was achieved along with moderate mineralization (COD removal ratio: 60-80%). COD (178.0-285.0 mg L -1 ) and NH 4 + -N (55.0-76.0 mg L -1 ) were degraded by 62% and 96%, respectively, at the optimum conditions (electrode gap: 0.5 cm, current density: 15.6 mA cm −2 ) after 60 min treatment. Under this optimal condition, the corresponding energy consumption was 8.60 kWh m -3 for effluent meeting the discharge standards. Furthermore, gas chromatography-mass spectrometry (GC-MS) analysis indicated that this technique could be employed to eliminate bio-refractory and toxic compounds such as phenanthrene, indole, quinoline and pyrimidine in coking wastewater. CONCLUSION: Ti/RuO 2 -IrO 2 anode systems were confirmed to be effective in advanced treatment of biologically pretreated coking wastewater. NOTATION E S Energy consumption (kWh m −3 ) U Average cell voltage (V) I Applied current (A) T Electrolysis time (h)

Potential control of cyanobacterial blooms by using a floating‐mobile electrochemical system

“…The electrochemical cell was equipped with three mixed metal oxide (MMO) titanium coated electrodes as anodes (RuO 2 ‐IrO 2 , Pt‐IrO 2 , PbO 2 ) and four uncoated Ti mesh electrodes as cathodes (Magneto Special Anodes BV, The Netherlands). Each electrode surface area was 4 × 6 cm, and the distance between the electrodes was adjusted to 0.6 cm, connected to the DC power supply adopting monopolar electrodes connection method . The electrodes were fixed to the underneath of a floating vessel made of Depron foam, with the top edge of the electrodes erected on the upper surface of the vessel bottom.…”

Trends in Research on Electrochemical Oxidation

“…High levels of NH 4 + -N removal (95.0 %) was achieved along with moderate mineralization (60.0−80.0 %) with Ti/RuO 2 -IrO 2 electrodes as anodes in the advanced treatment of biologically pretreated coking wastewater. 1 BDD showed high current efficiency and low energy consumption in ammonia removal, attributed to its high oxygen evolution overvoltage and low chloride evolution overvoltage (1.5V vs. SCE). 37 Exposures to herbicides/pesticides were associated with an increased Parkinson's disease risk in a dose-response relationship in the univariate analysis.…”

“…Furthermore, gas chromatography-mass spectrometry analysis indicated that this technique could be employed to eliminate biorefractory and toxic compounds such as azo dyes, phthalates, bisphenol-A, phenanthrene, indole, quinoline and pyrimidine in wastewater. 1,5 As a result, electrochemical oxidation related-research had attracted more and more attention in many fields, such as wastewater treatment, drinking water purification, disinfection, electrochemical determination and so on. 3,8−11 The limiting factor in implementing electrochemical technology for the effective degradation of organic pollutant is often the electrode material.…”

Factors controlling adsorption of recalcitrant organic contaminant from bio‐treated coking wastewater using lignite activated coke and coal tar‐derived activated carbon

“…Therefore, elimination of ROC before being sent to the reuse system is an urgent need being long pursued. Different approaches have been studied in terms of polishing biological effluent, such as coagulation, ozonation, reverse osmosis and advanced oxidation processes …”

“…Different approaches have been studied in terms of polishing biological effluent, such as coagulation, ozonation, reverse osmosis and advanced oxidation processes. 6,7 Adsorption on activated carbon is proven to be an effective technology to remove organic pollutants from wastewaters, owing to the large surface area, economic viability and easy operational procedures. Nevertheless, the difficult and costly regeneration process limits its application, and exhausted carbon incurs a serious disposal problem.…”