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Park, Gikonyo, Schmidt, Tobiason Develop Greener Wastewater Treatment Technology Supported by the NSF Partnerships for Innovation

Photogranules in hydrostatic cultivation (left) and in reactors treating wastewater (right)

Photogranules in hydrostatic cultivation (l), in reactors treating wastewater (r)

An interdepartmental team from the College of Engineering will work together to push the oxygenic photogranule (OPG) process, a UMass lab-born and patented technology, toward commercialization to address the world’s needs for effective and sustainable wastewater treatment. A new $550,000 grant from the National Science Foundation, titled “PFI-RP: Developing Light-Controlled Mixing to Advance Energy Efficient Wastewater Treatment by Oxygenic Photogranules,” will support the team’s research, outreach activities, and student researchers’ entrepreneurship development.

The team is composed of Professor Chul Park of the Civil and Environmental Engineering (CEE) Department, the principal investigator for this new grant, and two co-PIs: Professor John E. Tobiason, P.E., the new department head of CEE; and Professor David P. Schmidt of the Mechanical and Industrial Engineering Department. Another co-PI is Dr. David Rhu from BKT, Co., Ltd. who will lead the project as the industry mentor. Joseph Gikonyo – Park and Tobiason’s co-advisee Ph.D. student in CEE – who contributed significantly to developing this awarded proposal, will be a student research and business lead for this project.

Park explains that OPGs are microbial aggregates composed of oxygen-producing photosynthetic microbes and other microbes, growing in spherical shape. Since Park and Sona Dolan co-invented the discovery of OPG formation in a CEE laboratory, they have carried out extensive research on this “photogranulation” phenomenon.

As Park commented, “It has been fascinating experience to learn about this phenomenon. It seems like this phenomenon has been always with us, basically from the time when living entities appeared on earth. It continues to occur these days in many different environments, even in the environment unlikely to support the photogranular growth, polar glaciers.”

Park added: “However, it seems that photogranules can still be grown only under given environmental settings, because, if you miss one condition, you lose this phenomenon. We have been investigating to decode this secret.”

While basic research on OPGs are underway in Park and his collaborators’ laboratories, the PFI team is working to advance the application of OPGs for wastewater treatment. Park contends that the OPG process requires less electricity to provide oxygen for treatment ordinarily used in treating wastewater, as well as incorporating atmospheric carbon dioxide into easily separable grown biomass.

Park said that “The current usage of electricity by wastewater treatment is not trivial. In the U.S., wastewater treatment systems alone use about 25 percent of municipal energies, and up to 60 percent of this energy is designated for aeration in the treatment systems.”

As his project abstract explains, “This [process] could be retrofitted in the infrastructure in developed countries and could be included in new wastewater treatment facilities. For regions where wastewater treatment is absent or inadequate, sanitation via the OPG technology can potentially improve public health and the environment at a lower cost than conventional technology.”

Park notes that this process has been demonstrated successfully at small scales, but scale-up and implementation requires the scientific and technical advancements described in his NSF proposal.

The proposal abstract explains that, despite prior advancements in photogranulation knowledge and success of bench-scale OPG systems, “process scale-up in a natural light setting recently failed after initial success. The PIs hypothesize that this outcome was due to photoinhibition of photogranulation, which has not been studied in previous OPG research.”

Objectives of the proposed research are to investigate the photoinhibition phenomenon by studying the photochemical capacity and the photosynthesis range of the OPG process, and to develop a fluid-mixing and irradiance-based method to limit photoinhibition of OPG reactors.

“Integrating these critical new knowledge sets is expected to yield an innovative irradiance-based mixing scheme to control photoinhibition and support adequate oxygenic photosynthesis,” say Park and his collaborators. “Research methods include operation of batch and continuous flow reactors under different irradiance and mixing conditions and modeling of reactor hydrodynamics and OPG transport. These activities will significantly improve knowledge of photogranulation and enhance the translation of a new wastewater treatment technology to a commercial scale.”

The PFI research also includes a new collaborative plan with Dr. Jeeyon Jeong, an assistant professor in the Department of Biology at Amherst College, to determine photochemical range of OPGs. In addition, the project includes significant advanced training of future engineers and scientists, including underrepresented groups. Outreach to students, increased graduate study opportunities for women and minorities, and technology transfer are also benefits to the society at large. (October 2019)