Muhammad's research investigates various ecological and microbial aspects of advanced biological wastewater treatment processes, including aerobic granular sludge (AGS) system and biological nitrogen removal processes, particularly anaerobic ammonium oxidation (anammox) process. His primary focus is to understand these engineered ecosystems by metagenomics and metatranscriptomics profiling using high-throughput sequencing, which includes next-generation "short-read" and third-generation "long-read" sequencing methods. Further understanding of these bioprocesses' application would optimize wastewater reuse technologies to provide fit-for-purpose reuse water quality with minimum energy inputs, resources, and carbon footprint.