Electrocatalytic Hydrogenation of Bioinhibiting Aromatics to Bioavailable Aliphatics for Wastewater Denitrification
Shan Shao1, Shicong Du1, Asma Batool1
1School of Energy and Environment and State Key Laboratory of Marine Environmental Health, City University of Hong Kong, Kowloon Tong 999077, Hong Kong SAR, China.
Abstract:
Biological denitrification is a key process for nitrogen removal in wastewater, enabling the conversion of nitrate (NO3-) to nitrogen gas (N2). However, this process can be inhibited in the presence of aromatic substrates. Conventional advanced oxidation protocols involve the mineralization of aromatics, but the widespread adoption of such protocols is limited by high energy and chemical requirements. In this study, we present a novel electrochemical hydrogenation (ECH) protocol to transform bioinhibiting aromatics into bioavailable aliphatic products, thereby promoting biologically driven denitrification. A highly active carbon-supported ruthenium electrode was designed to convert various unsaturated, aromatic, and halogenated aromatic pollutants into aliphatic products, achieving conversion efficiencies of 66.0%-100%. After 5 day incubation, the saturated products enhanced the denitrification rate by up to 614.0%. The relative abundance of denitrifiers in the sequencing batch reactor landfill sludge increased, confirming that the aliphatic products from ECH treatment could enhance bioavailability. This work demonstrates the integration of electrochemical and biological catalysis, valorizing pollutants into biologically useful products that can improve denitrification, especially in existing high-organic-load wastewater treatment networks.
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