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Project

Assessing the applicability of ozonation and CuO based AOP’s in the degradation of recalcitrant organic compounds from wastewater

The availability of freshwater resources has become one of the huge challenges worldwide due to ever-increasing water quality problems. Emerging micro-pollutants such as pharmaceuticals, personal care products (PPCPs) and other synthetic organic components largely contribute to this issue. Hence, the removal of these micro-pollutants from wastewater and their presence in reclaimed water have received a lot of attention. They are difficult to be treated by traditional wastewater treatment methods (e.g., biological treatment) due to their persistent and recalcitrant properties. In this regard, more efficient and sustainable treatment processes should become available urgently.

Advanced Oxidation Processes (AOPs) have been demonstrated to be a promising technique to deal with these issues due to the in-situ generation of strong oxidative radicals to degrade bio-recalcitrant organic compounds. Various AOPs have been applied for the removal of a myriad of recalcitrant organic micro-pollutants. However, regardless of the conventional AOPs represented by ozone-based processes or emerging AOPs represented by catalysts-based processes, there are different challenges to be further solved in terms of technical, economic and environmental aspects. Therefore, several represented conventional and emerging AOPs have been selected in this research to compare their applicability for the removal of recalcitrant organic pollutants.

In Chapter 2, sodium percarbonate (SPC) is introduced to activate the O3 system as a substitute for H2O2 for the degradation of dichlorvos (DDVP). The DDVP removal performance is systematically evaluated in terms of initial pH, O3 dosage, SPC dosage and water matrix. The results indicate that the O3/SPC system could be further investigated as a novel oxidation process for the elimination of recalcitrant compounds. In Chapter 3, an ozone-based AOP (O3/UV) is employed on the degradation of benzalkonium chloride (DDBAC). Unlike O3 treatment, the O3/UV treatment is an efficient method for removing DDBAC under low ozone dosage and neutral pH values, which is attributed to the catalytic effect of UV towards O3. Based on the achieved results, it will benefit industries to a greater extent.

In Chapter 4, the performance of direct UV and CuO/peroxymonosulfate (CuO/PMS) systems are compared in terms of DDBAC degradation under various conditions. The applicability of direct UV and CuO/PMS systems for the treatment of water are proposed. In Chapter 5, two main oxidation systems including PMS alone and CuO/PMS system are used to assess their effectiveness to deal with the synthetic effluents containing various types of recalcitrant pollutants, i.e., methylene blue (MB), methyl orange (MO), ciprofloxacin (CIP), Rhodamine B (RhB). It can be concluded that the application of PMS alone can be a good option to deal with low-strength effluents such as polluted water containing relatively low concentrations of less recalcitrant pollutants (MO). However, the CuO/PMS system is quite efficient when dealing with high-strength effluents such as polluted water containing high concentrations or more recalcitrant organic compounds. This study recommends the most sustainable options to treat effluents with various degrees of strength. In Chapter 6, the innovative biochar/CuO and biochar/Fe3O4/CuO composite catalysts are synthesized and employed to activate PMS for the degradation of RhB. The addition of magnetite to CuO nanomaterial suppresses the PMS activation performance to some extent, while there is a negligible effect on the doped biochar ratio. Combined with PMS, the biochar/Fe3O4/CuO composite provides a sustainable and potential alternative for the degradation of recalcitrant organic pollutants from wastewater.

In general, ozone-based AOPs and CuO-based AOPs are quite efficient for the removal of various recalcitrant organic compounds from wastewater. As representative conventional AOPs, ozone-based AOPs can be easily employed in large-scale applications. However, although CuO-based PMS AOPs exhibit many advantages compared with other conventional AOPs, there are still some challenges to applying the nanomaterials directly on a large scale. Furthermore, the selection of AOPs depends on the property of treated pollutants and the pollution load of the wastewater. The results from this research provide criteria to select the most suitable AOPs. 

Date:25 Sep 2017 →  16 Nov 2021
Keywords:AOPs, ozonation, CuO nanomaterial, recalcitrant compounds, wastewater
Disciplines:Inorganic chemistry, Organic chemistry, Theoretical and computational chemistry, Other chemical sciences
Project type:PhD project