Prof. Ruan is widely recognized for his research in biomass and solid waste conversion, including plastic waste pyrolysis and gasification to produce chemicals, materials, fuels, and energy. His work extends to innovative wastewater treatment and utilization solutions, airborne pathogen disinfection, catalytic non-thermal plasma, microwave and photocatalytic technologies, and food engineering advancements. His research has resulted in significant contributions to engineering knowledge, with over 50,000 citations, an h-index of 112, and an i10-index of 574. Dr. Ruan has been elected and inducted into US National Academy of Engineering (NAE), is also a Fellow of US National Academy of Inventors (NAI), the American Society of Agricultural and Biological Engineers (ASABE) and the Institute of Food Technologists (IFT), among others.