We are facing grand challenges in the nexus of food, climate, and water. As an engineer in environmental and biochemical engineering, of importance are to transfer ground-breaking discoveries and develop innovative technologies applicable to low-carbon-footprint purification technologies, energy autarky wastewater treatment, mitigation of greenhouse gas emissions, and production of valuable compounds from wastes. Given substantial progress on analytical tools looking into microbial resources in natural environments, surprising discoveries on the functions of unexplored microorganisms have been reported. This symposium invites leading researchers working in the field and discusses the significance of managing and harnessing microbial communities for water reuse/recycle, sustainable society development, and global warming mitigation.