Korea University and Harbin Institute of Technology unlock new pathways in circular waste-to-energy solutions

With increasing pressure on global resources and the urgent need for climate action, the concept of “waste” is undergoing a major transformation. No longer viewed as the end point of consumption, waste is now being redefined as a valuable starting point within a circular economy. Prof. Yong Sik Ok of Korea University is at the forefront of this shift, advocating for science-driven strategies that convert waste into critical materials, renewable energy, and economic value. In the context of post-pandemic recovery, his work highlights how circular economy principles are evolving into a key driver of industrial and environmental transformation.

Prof. Yong Sik Ok of Korea University is a leading researcher advancing circular economy solutions for waste management and renewable energy. His work emphasizes transforming waste into valuable resources through plastic circularity, resilient waste systems, and biomass-to-energy innovations. Collaborating with global researchers, including Harbin Institute of Technology, his team has developed advanced technologies such as microbial electrolysis cell–anaerobic digestion (MEC–AD), significantly improving methane production and system stability for sustainable energy recovery.

Plastic Circularity: From Reduction to a Closed Loop
Plastic waste continues to be a global environmental concern, and traditional reduction strategies alone are no longer sufficient to tackle its complexity. In research published in Nature Reviews Earth & Environment (2021), Prof. Ok emphasizes the need to transition from linear consumption models to closed-loop systems. His work advocates for “intelligent design” at the production stage and the adoption of advanced upcycling technologies to convert plastic waste into high-value materials. This approach not only minimizes environmental impact but also enhances long-term resource efficiency and industrial sustainability.

Resilient Chains: Building Waste Management Systems for Uncertainty
The vulnerabilities of global waste management systems were starkly exposed during the COVID-19 pandemic. Findings published in Science (2020) highlight how sudden disruptions can lead to environmental degradation and social inequities. Prof. Ok’s research underscores the importance of embedding resilience and disaster preparedness into waste management frameworks. Modern systems must go beyond routine waste handling to function as critical infrastructure that safeguards public health and environmental stability, even under extreme conditions.

Biomass Empowerment: An Efficient Energy Factory for Value Recovery
Biomass waste, including fruit and vegetable waste and waste activated sludge, represents a significant opportunity for renewable energy generation. Through anaerobic digestion (AD), microorganisms break down organic matter in oxygen-free environments to produce biogas, primarily methane. This methane can be used for electricity generation, heating, or upgraded into bio-natural gas. Additionally, carbon dioxide and nutrient-rich residues generated during the process can be repurposed into valuable chemicals and agricultural inputs. However, conventional AD systems often face challenges such as over-acidification, which limits efficiency and stability.

To overcome these limitations, Prof. Ok collaborated with Prof. Xue-Ting Wang from Harbin Institute of Technology to develop a hybrid microbial electrolysis cell–anaerobic digestion (MEC–AD) system. As reported in Bioresource Technology (2026) and Chemical Engineering Journal (2025), this system integrates electrodes and low-voltage inputs to enhance microbial activity. The innovation achieves a 65.4% increase in methane production while improving system stability. The research also highlights a functional partitioning mechanism within the system, where bio-anodes drive methane production, bio-cathodes stabilize the process by reducing acid accumulation, and suspended microbes facilitate the breakdown of complex organic matter. This advancement significantly improves the efficiency and reliability of biomass-to-energy conversion.

Responsible Innovation: A New Era of Circular Economy
Prof. Ok’s work reflects a broader vision of integrating multiple waste streams and technologies into a cohesive circular economy framework. By combining plastic circularity, resilient infrastructure, and advanced biomass conversion technologies, his research demonstrates how waste can be transformed into a strategic resource. This integrated approach not only addresses environmental challenges but also contributes to energy security and sustainable economic development.

Researcher extraordinaire
Prof. Ok and his team’s exemplary research work has yielded a remarkable portfolio that includes a series of influential publications addressing critical challenges in plastic circularity, waste management resilience, and biomass-to-energy conversion through innovative technological solutions. Some of these publications are highlighted below:

1. “The COVID-19 pandemic necessitates a shift to a plastic circular economy”, featured in Nature Reviews Earth & Environment (2021, DOI: https://doi.org/10.1038/s43017-021-00223-2).
2. “COVID-19's unsustainable waste management”, published in Science (2020, DOI: https://doi.org/10.1126/science.abc7778).
3. “Linking microbial functional partitioning with methane productivity and stability in microbial electrolysis cell–anaerobic digestion hybrid systems”, published in Bioresource Technology (2026, DOI: https://doi.org/10.1126/science.abc7778).
4. “Mitigating over-acidification and enhancing methane production in hybrid microbial electrolysis cells–anaerobic digestion (MEC–AD)”, featured in Chemical Engineering Journal (2025, DOI: https://doi.org/10.1016/j.cej.2025.164749).

It is undeniable that Prof. Ok, along with his collaborators, continues to push boundaries with their innovative research initiatives. Not only are they advancing scientific understanding, but they are also delivering practical and scalable solutions to some of the most pressing environmental challenges, helping shape a more sustainable and resource-efficient future for the world.

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About Professor Yong Sik Ok
Professor Yong Sik Ok currently serves as President of both the International ESG Association and the International Society of Trace Element Biogeochemistry. In 2022, he was recognized as a Highly Cited Researcher (HCR) in three fields—Environment and Ecology, Engineering, and Biology and Biochemistry. He was also the first Korean scientist to receive HCR recognition in Environment and Ecology, beginning in 2019. In 2025, Prof. Ok was ranked first globally in Environmental Sciences by ScholarGPS. His Google Scholar profile shows an h-index of 193, over 140350 citations, and 108 highly cited papers. He leads global research and serves as Editor-in-Chief of CleanMat.

About Professor Xue-Ting Wang
Professor Xue-Ting Wang is an Associate Research Professor at the School of Environment, Harbin Institute of Technology, China. Her research focuses on low-carbon treatment and resource recovery from organic wastewater and biowaste. She has led multiple national and provincial projects, including funding from the National Natural Science Foundation of China and the National Key R&D Program. In recent years, she has published extensively in high-impact SCI journals such as Nature Communications, Water Research, and Chemical Engineering Journal. She also contributes as a reviewer for leading journals, supporting advancements in sustainable environmental technologies and mentoring students in interdisciplinary environmental research fields.