Photocatalytic ozonation under visible light for the remediation of water effluents and its integration with an electro-membrane bioreactor

Abstract

Photocatalysis and photocatalytic ozonation under visible light have been applied for the purification of a complex aqueous matrix such as the grey water of Masdar City (UAE), by using N-doped brookite-rutile catalysts. Preliminary runs on 4-nitrophenol (4-NP) solutions allowed to test the reaction system in the presence of a model pollutant and to afford the relevant kinetic parameters of the process. Subsequently, the remediation of grey water effluent has been evaluated in terms of the reduction of total organic carbon (TOC) and bacterial counts. The concentration of the most abundant inorganic ionic species in the effluent has been also monitored during reaction. Photocatalytic ozonation under visible light allowed to reduce the TOC content of the grey water by ca. 60% in the optimized experimental conditions and to reduce the total bacterial count by ca. 97%. The extent of TOC mineralization reached ca. 80% when the photocatalytic ozonation occurred downstream to a preliminary electro-membrane bioreactor (eMBR). Coupling the two processes enhanced the global efficiency. In fact, the eMBR treatment lowered the turbidity and the organic load of the effluent entering the photocatalytic ozonation treatment, which in turn enhanced the extent of purification and disinfection.

Investigation on the Urban Grey Water Treatment Using a Cost-Effective Solar Distillation Still

“…In another study by Itayama et al [17], the COD, the BOD, the SS, the TN, and the TP in the kitchen basin grey water were reduced from 271 mg/L, 477 mg/L, 105 mg/L, 20.7 mg/L, and 3.8 mg/L to 40.6 mg/L, 81 mg/L, 23 mg/L, 4.4 mg/L, and 0.6 mg/L, respectively, using a slanted soil filter. The chemical treatments of grey water were studied in a few studies, such as the use of an electro-coagulation process followed by a disinfection stage [25], the application of coagulation systems with the magnetic ion exchange resin process, and the coagulation process using aluminum salt [26] as well as application of photocatalytic ozonation [27]. Several studies investigated the performances of several biological treatment techniques such as rotating biological contractor (RBC), sequencing batch reactor (SBR), anaerobic sludge blanket (UASB), constructed wetland (CW), and membrane bioreactors (MBR)) in order to treat medium-and high-strength grey water.…”

Surface and Electronic Features of Fluorinated TiO2 and Their Influence on the Photocatalytic Degradation of 1-Methylnaphthalene

“…However, despite the huge amount of papers published so far on environmental remediation by TiO 2 photocatalysis, large-scale applications for water treatment are hardly viable because of the large volume of effluents to be treated and to the low reaction rates exhibited in the presence of highly concentrated pollutants. Coupling photocatalysis with other advanced oxidation processes can be an economically sustainable alternative because of the efficiency enhancement resulting from the synergy between the concomitant processes. − On the other hand, photocatalysis alone can be competitive with traditional remediation processes for niche applications, such as the degradation of nearly insoluble pollutants in aqueous media downstream to physical separation plants. In fact, oil separation is a time-consuming step in conventional plants and does not generally provide the required level of decontamination in reasonable treatment times.…”

Simultaneous Removal and Recovery of Metal Ions and Dyes from Wastewater through Montmorillonite Clay Mineral

“…The disposal of wastewaters from various origins represents a serious environmental issue due to the simultaneous presence of different types of pollutants [1][2][3][4]. Dyes and metals are widely used and often jointly released in large quantities from industrial activities such as dye manufacturing, the textile and leather tannery industries, pulp and paper processing, battery production [5][6][7][8][9][10][11].…”