A professor in NUS since 1998, he works in the field of environmental and chemical engineering, focusing on R&D in membrane, adsorption, microplastics, carbon sequestration, resource/energy recovery, heavy metals, ballast water management, and exhaust gas treatment. Paul has served as a PI or co-PI for over 20 government funded projects. Paul's work ranges from basic research, set-up, and fabrication and operation of full-scale systems. He is trained over 90 PDFs and PhD / MSc students. He is authored over 250 research articles/book chapters, most of which are published in several prestigious journals, such as Chemical Society Reviews with H-index of 74 and citation of over 20,000 and nine of his papers listed as “highly cited”/“hot” papers by Calrivate Analytics.

Paul has been ranked in the Top 2% of scientists in the world by Stanford-Elsevier since it was started. He authored one book published by CRC and has five edited books by CRC and Springer. He has 12 patents, half of which are being commercialized. He has served as an expert for the review of research proposals for over 20 funding agencies (e.g., USNSF, NRF and RGS). He is in the editorial boards of over 20 journals and publishers, including JCIS and CRC. He is in management committees of several prestigious professorial societies, such as Chair of Nano & Water SG of IWA, Vice Chair and a Congress Member of IChemE and an examiner for Chartered Engineer/Scientist of Engineering Council/Science Council. He is a Chartered Engineer/Scientist, and an elected FRSC, FIChemE, FIET, FIWA, and FIMarEST.

Paul is a recipient of a number of research awards, including the IChemE Sustainable Technology Award and has been invited to deliver keynote speeches in JCIS and IWA conferences.