Down-Flow Hanging Sponge (DHS) Reactors

Vinay Kumar Tyagi is a Scientist D at the Environmental Hydrology Division, National Institute of Hydrology, Roorkee, India. His research interests include anaerobic digestion, energy-efficient wastewater treatment systems, sludge management, and advanced biomass pretreatment methods. He has over 100 publications to his credit, including full-text books, over 40 book chapters and manuals. Dr. Tyagi is a Fellow and Life Member of several professional bodies and organizations. He is a Management Committee Member of the International Water Association (IWA) Sludge Management Specialist Group and represents the South Asia Division, and also the Anaerobic Digestion Specialist Group. Dr. Tyagi has extensive international research exposure and collaborations in Norway, Taiwan, Spain, Japan, and Singapore in various environmental research domains of wastewater treatment, sludge pretreatment, and biomass to bioenergy recovery.

Takahiro Watari is an Associate Professor at the Department of Civil and Environmental Engineering, Nagaoka University of Technology, Niigata, Japan. His research interests include advanced wastewater treatment systems such as anaerobic industrial wastewater treatment, low-cost aerobic sewage treatment, and recirculating aquaculture systems. Dr. Watari has published over 80 publications to his credit. Dr. Watari’s research achievements have received many academic honors: (1) Japan Open Innovation Prize, Prime Minister’s Award; and (2) Best Annual Paper Award of the Japan Society on Water Environment. Dr. Watari has extensive international research exposure and collaborations in Korea, Vietnam, Thailand, Malaysia, Indonesia, India, Kenya, Egypt, Belgium, the Netherlands, and Chile in various environmental research domains such as wastewater treatment, recirculating aquaculture systems, and water supply.

Tsutomu Okubo, Professor at National Institute of Technology, Kisarazu College, Japan, is a Civil Engineer with a PhD degree from Tohoku University. His research interests include biological wastewater treatment, water pollution surveys, and related microbial risks to humans. Dr. Okubo has been involved in the development of sewage treatment systems based around down-flow hanging sponge (DHS) technology, which uses sponges as microorganism retention carriers. He is an expert in demonstration experiments, having lived and worked at a Karnal sewage treatment plant in India to demonstrate the proposed technology, and conducting experiments in Egypt after becoming a Professor. The proposed system is being applied mainly in developing countries as a system with low energy consumption and low excess sludge generation, and experiments are underway in Malaysia and Thailand. He has published with colleagues over 60 research papers in international journals and received numerous awards at national and international conferences.

Hideki Harada is currently Professor Emeritus at NUT and TU, as well as the CEO of “DHS Technology Co. Ltd.”. His research interests are mainly focused on the development of lowcost wastewater technology from an engineering perspective, and microbial ecology analysis in wastewater treatment processes from a scientific perspective. During his NUT years, he was dispatched to AIT (Asian Institute of Technology, which is an international autonomous institution, located in Bangkok, Thailand), where he devoted himself for 2 years to education and research for graduate students from developing countries throughout Asia. Through his experience at AIT, he became aware of the significance of R&D in appropriate technology for wastewater treatment applicable to developing countries. As a consequence, his research concern was linked with his originally developed technology, i.e., DHS, as one of his lifelong research topics. He (co-)authored 400 scientific papers and book chapters, and has gained an international reputation.