Electrochemical methods and membrane bioreactor approach for wastewater treatment and water quality assessment

Abstract

Severe water scarcity, high health standards, and strict disposal limits have necessitated the development of novel and robust strategies for wastewater remediation and water quality analysis at lower cost with reduced energy expenditure. Electrochemistry offers promising and environmentally compatible approaches for the treatment of wastewater and for water quality assessment. Meanwhile, membrane bioreactor (MBR) technology is widely recognized as an effective method for enhanced wastewater treatment or re-use. In this study, an enhanced electrochemical oxidation process was first developed for the decontamination of phenolic compounds. Subsequently, a thermophilic submerged aerobic membrane bioreactor (TSAMBR) integrated with electrochemical oxidation (EO) was constructed for the treatment of thermomechanical pulping pressate. Finally, a photoelectrochemical method was proposed for the rapid determination of chemical oxygen demand (COD). A novel process based on an adsorption and release step followed by electrochemical oxidation was developed for the decontamination of three phenolic compounds: Phenol, p-nitrophenol (p-NPh) and p-cresol. The adsorption step was carried out by adsorbing the three pollutants onto a hyper-cross-linked resin (MN-200). The adsorption equilibrium and kinetics, as well as temperature effects were systematically studied. The MN-200 resin exhibited a high removal efficiency of the three pollutants and the adsorbed phenolic compounds can be efficiently released in a NaOH solution. The pre-concentrated phenolic compounds were further treated via electrochemical oxidation at a Ti/SnO2–Sb2O5–IrO2 electrode. The first-order model fitted the kinetics data of the electrochemical oxidation very well, showing that the degradation rate constant decreased in the order of p-NPh > phenol > p-cresol. The integration of the effective pre-concentration process with the electrochemical oxidation offers a promising approach for the effective decontamination of phenolic pollutants in wastewater.