Recalcitrant Wastewater Treatment Done Right
Advanced oxidation system based on a novel synergistic approach to remove organic compounds from industrial wastewater
Organic compounds are the main pollutants in industrial effluents, such as those released by pharmaceutical industries, oil refineries, and coke plants. Some aromatic compounds, such as phenols, cannot be effectively removed by conventional physicochemical and biological treatments and pose a serious threat to the ecosystem and public health. Conventionally, advanced oxidation processes (AOPs) are used to treat phenol-containing water, for example, drinking water, wastewater and contaminated groundwater. Classical AOPs use ozone or the Fenton reaction, which produces hydroxyl (•OH) radicals to degrade and mineralize phenol compounds.
However, these current processes require the continuous addition of expensive chemical reagents. Moreover, the non-recyclable soluble iron salts from certain AOPs produce a large amount of iron sludge, which needs to be further separated from the treated water. These issues significantly increase the associated costs of currently used AOPs. There is thus a need for better tertiary wastewater treatment systems that overcome these limitations.
We have developed an advanced oxidation system that synergistically produces hydroxyl radicals from multiple sources. In this system, •OH groups are generated in an electrochemical cell, which, upon UV illumination, yields more •OH groups and H2O2. Moreover, in the presence of Fe2+ ions, an electro-Fenton reaction is triggered. This leads to the degradation of organic contaminants through multiple reactions.
The proposed system yields mineralization efficiencies that are 20% higher than those achieved by conventional approaches. Moreover, the synergistic quality of the reactions involved in the proposed system eliminates the need to add expensive chemical reagents, as by-products are continuously reused as reactants to produce •OH radicals. This results in reduced overall costs.