Domestic wastewater typically contains calorific energy which represents five times the energy required for treatment. Municipal wastewater treatment plants have the potential to capture most of the energy present in the waste organic matter, but smaller utilities treating less than 10 million gallons per day, which account for 97% of the wastewater treatment systems in the US, are often reluctant to adopt complex and often costly resource recovery systems. A treatment paradigm using anaerobic mainstream wastewater treatment for primary and secondary treatment can meet secondary standards, harvest the energy from organic matter and eliminate separate sludge digestion. The anaerobic baffled reactors - expanded granular sludge bed - microscreen system represents a transformational change in the wastewater treatment paradigm from multiple separate capital-intensive energy-consuming unit processes to fewer simpler unit processes that maximize energy productivity and payback.
The advantage of the proposed coupled hybrid anaerobic reactor system lies in the advancement of knowledge regarding the factors that control the microbial and solids dynamics to meet the performance goals of a low complexity energy-neutral system at ambient wastewater conditions. The hypothesis is that a hybrid anaerobic baffled reactors - expanded granular sludge bed - microscreen can treat raw wastewater to meet secondary standards and produce stoichiometric amounts of methane. The supporting objectives are to: 1) optimize the hybrid anaerobic reactor system with real wastewater at bench- to demonstration-scale to produce secondary treatment quality, 2) generate stoichiometric amounts of methane from BOD removal, 3) develop a process model to predict anaerobic baffled reactors - expanded granular sludge bed - microscreen performance, and, 4) evaluate the life cycle impacts of the hybrid system by characterizing details needed to add the linked expanded granular sludge bed and microscreen to an existing anaerobic baffled reactors life cycle assessment. The expected outcome is increased process understanding for design and implementation of a low complexity hybrid anaerobic system that will generate energy while conditioning the water for autotrophic nitrogen removal and phosphorus recovery. The team brings decades of experience in microbial process modeling, microbial ecology, environmental engineering, wastewater plant and utility operations. The research will facilitate state and federal regulatory acceptance and industry adoption of new energy positive technology for full-scale applications. The expected transformative results will be disseminated via numerous avenues including workshops at regional council meetings and national conferences, as well as a technology diffusion workshop that will engage change agents from the wastewater treatment industry. The proposed project will also broaden participation in STEM, as the PIs will continue their extensive history in this area by recruiting as researchers undergraduate and graduate students from underrepresented groups, as well as low-income first-generation community college students via our partnership with a local community college. The investigators will also translate conceptual content from these studies into established pre-college outreach efforts to inspire interest in STEM fields in local disadvantaged and predominantly minority school districts.
