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32. Ecological Risk Assessment and Sustainable Management of Pollutants in Hydroponic Wastewater from Plant Factories.

Author

Ryu, Hong-Duck, Kim, Jae-Hoon, Han, Hyeyeol, Park, Ju-Hyun, and Kim, Yong Seok

Abstract

Although the plant factory (PF) industry is expanding worldwide, there are currently no regulatory measures for wastewater discharged from PFs in South Korea. This study aims to present the characteristics of major pollutants discharged from PFs that have not been reported in the literature and suggest effective management measures for them. The occurrence of 17 pollutants in hydroponic wastewater (HW) from 33 PFs was analyzed, and their potential ecological risk (PER) to aquatic life was assessed. Water samples were collected up to three times from each PF. The detection frequencies of 11 pollutants, including total organic carbon, total nitrogen, total phosphorus, Mn, Ni, B, Mo, Cr, Cu, Zn, and Ba, in HW exceeded 50%. Ni, Cr, and Ba are notably not recommended components of nutrient solutions in South Korea. Among the micropollutants, the concentration of Cu, which is a recommended component, was the highest, at 10.317 mg/L. The PER assessment identified Cu and Zn as "high-hazard" pollutants, with Cu, Zn, Ni, Mn, and B prioritized for management. To ensure the sustainability of hydroponic cultivation, these five pollutants must be managed. Nature-based techniques, such as the implementation of constructed wetlands and phyto-filtration, are recommended for effective treatment. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Strategic usage of redox active materials and sacrificial Zn electrodes for spontaneous hydrogen evolution reaction.

Author

Jeong, Tae Yup, Gudal, Chandan Chandru, Kim, Byeongkyu, Kim, Yong Seok, Ha, Tae Yeon, Mule, Anki Reddy, Yoo, Pil J., and Chung, Chan-Hwa

Abstract

The availability of renewable energy in conventional water electrolysis is random and inefficient. Therefore, exploring the use of efficient materials and designs to improve the performance and durability of electrolysis in renewable energy systems makes it a promising and sustainable solution for green-hydrogen production. Here, the idea of strategically using a redox active material (RAM) as a mediator for storing energy chemically in conjunction with efficient water electrolysis is explained in this study. Another strategy is to use a sacrificial electrode and a RAM to address the disadvantage of traditional water splitting using external energy. The chosen RAM, 2,5-dihydroxy-1,4-benzoquinone (DHBQ), has high solubility, low cost, reversibility, and negative potential in aqueous systems. The spontaneous hydrogen evolution reaction (HER) module was designed based on the standard reduction potential difference between DHBQ and the HER, confirming a maximum power density of 43.12 mW cm−2 at 100 mA cm−2. The oxygen evolution reaction (OER) and the Zn module showed efficient energy utilization in the DHBQ reduction tests. Comparative experiments with an alkaline water electrolyser (AEMWE) and an acidic water electrolyser (CEMWE) vs. our OER–HER system revealed a total energy consumption of 30.4% lower than the average of others, demonstrating efficient energy use. Moreover, both modules achieved spontaneous operation in the complete system with the Zn sacrificial electrode, resulting in a maximum power density of 40 mW cm−2 for the Zn module and 43.12 mW cm−2 for the HER module. Overall, the demonstrated energy output was 1.85 W h per LH2. This innovative approach ensures the utilization of components and reduces power consumption, making it a promising solution for sustainable hydrogen production. [ABSTRACT FROM AUTHOR]

Published
2024
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