image: A schematic comparing traditional electro-Fenton and fluidized bed reactor-based electro-Fenton methods. / In the case of conventional reservoir-type water treatment (left), the oxygen (reactant) for hydrogen peroxide generation is low concentrations of dissolved oxygen, whereas in the case of flow-through reactor-based systems (right), high concentrations of oxygen gas are directly injected, resulting in high hydrogen peroxide generation characteristics. In addition, the circulating electrolyte allows for efficient organic removal by inducing the dispersion of excess hydrogen peroxide generated at the electrodes.
Credit: Korea Institute of Science and Technology
Conventional wastewater treatment involves the centralized collection of wastewater from sources through pipes to large-scale treatment plants, where it is treated in bulk. However, this is not feasible in small, decentralized areas such as rural areas. Simple treatment units installed at small non-point sources of pollution mainly focus on disinfection and turbidity improvement, and do not properly decompose the recalcitrant organic matter in wastewater. In addition, even if industrial wastewater is treated in-house, the treatment efficiency is low, and highly toxic wastewater often needs to be re-transported to a final treatment plant.
Dr. Sang Hoon Kim, Extreme Materials Research Center, Dr. Jong Min Kim, Materials Architecturing Research Center, and Dr. Sang Soo Han, Computation Science Research Center, all from the Korea Institute of Science and Technology (KIST), have developed an electrochemical device that can treat sewage and wastewater from pollution sites to the level of discharge. In particular, it can rapidly and completely decompose recalcitrant materials into inorganic substances and discharge them on its own.
While previous research methods mainly focused on the development of electrode materials for the generation of hydrogen peroxide, a powerful electrochemical oxidant, this study introduced a flow cell method to generate a large amount of hydrogen peroxide while circulating wastewater in the device, mixing it well, and oxidizing and decomposing recalcitrant organic matter in situ to rapidly mineralize it. This is a structure that can completely degrade organic matter much more efficiently than conventional treatment tanks.
Conventional oxidation treatments for harmful organics in water often require multiple steps before the organics are completely degraded, and the intermediate products are often still toxic. When organic matter in water is completely decomposed and mineralized, it becomes non-toxic and can be discharged, and the indicator of this is called total organic carbon (TOC). Since last year, after 48 years, the Ministry of Environment has added total organic carbon to the wastewater discharge standards to impose stricter wastewater treatment standards. The small-scale electrochemical device developed by the KIST research team is a technology that can effectively treat sewage and wastewater directly on-site, which is difficult to treat centrally, and can effectively reduce the total organic carbon in a short time. In fact, the researchers demonstrated excellent complete decomposition performance, reducing the total organic carbon of 50pm bisphenol A by 93% in 2 hours.
"The developed device is composed of a continuous and repetitive flow method, which shows higher complete decomposition efficiency than the existing method, and a patent is pending for the device and processing method. We are also planning to transfer the technology to commercialize it."
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KIST was established in 1966 as the first government-funded research institute in Korea. KIST now strives to solve national and social challenges and secure growth engines through leading and innovative research. For more information, please visit KIST’s website at https://eng.kist.re.kr/
This research was supported by the Ministry of Science and ICT (Minister Yoo Sang-im) under the KIST Institutional Program, Usu Shinjin (RS-2023-00209940), Nanomaterial Technology Development Project (NRF-2022M3H4A7046278), and the Ministry of Environment (Minister Han Hwa-jin) Environmental Technology Development Project (2021002800005). The research was published in the latest issue of the international journal Applied Catalysis B: Environment and Energy (IF: 20.2 JCR, top 0.6%).
Journal
Applied Catalysis B Environment and Energy
Article Title
Higher-valent nickel oxides with enhanced two-electron oxygen reduction in advanced electro-Fenton system for organic pollutants degradation
Article Publication Date
1-Oct-2024