GOALI: Understanding granulation using microbial resource management for the broader application of granular technology

The aerobic granular sludge (AGS) process has emerged as a promising biological wastewater treatment technology that is energy and carbon-efficient with a smaller footprint requirement compared to conventional activated sludge systems. Despite these advantages, the implementation of the AGS process has been slow, especially in the United States, due to several critical engineering challenges including the lack of robust operational data and fundamental knowledge on how to integrate the AGS process into flow-through reactor systems.

In this GOALI project, the lead academic institution (University of Utah) and the industrial partner (DC Water) will combine and integrate their expertise, experience, and resources to address these critical challenges. To advance this goal, the academic partner will focus on the fundamental science of reactor operation, bacterial community analysis in different granular reactors, and kinetic analysis and modeling.

The industrial partner will provide guidance and input in the design of the kinetic experiments, kinetic data analysis, student training and internship, and the translation of the research results to guide the design of full/pilot-scale systems. The successful completion of this project will benefit society through the generation of new fundamental knowledge to advance the design and implementation of granular activated sludge technology in flow-through reactor systems.

Additional benefits to society will be achieved through student education and training including the mentoring of two graduate students and two undergraduate students at the University of Utah.

Unlike the loose bacterial flocs of conventional activated sludge systems used in most large-scale wastewater treatment plants (WWTPs), aerobic granular sludge (AGS) reactors rely on fast-settling, round, compact biofilms called granules that circumvent the need to have separate aerobic-anoxic-anaerobic zones. In addition, they do not require a secondary gravity settler for a follow-up clarification step.

However, the implementation of flow through AGS reactors and their integration into large-scale WWTPs has remained elusive due to a lack of robust operational data and fundamental engineering knowledge. To address these critical knowledge gaps, this GOALI project will generate validated kinetic data in sequencing batch and flow through AGS systems as a function of two critical operational parameters including temperature and food to microorganisms (F/M) ratio.

The specific objectives of the research are to 1) investigate and characterize the granulation process as a function of F/M ratio and temperature in sequencing batch reactors; 2) investigate the process of granulation in a continuous flow-through reactor using optimal temperatures and F/M ratios that are selected following the completion of Objective 1; 3) construct functional gene networks existing in both granules and flocs under steady-state conditions and external perturbations and connect these networks with reactor performance using theoretical ecology and; 4) integrate findings into process design and operational protocols for the optimal operation and maintenance of flow-through AGS reactors in close collaboration with D.C. water. To implement the educational and training goals of this GOALI project, the Principal Investigator (PI) proposes to leverage existing programs at the University of Utah College of Engineering Diversity Office to recruit and mentor undergraduate students from underrepresented groups to work on this GOALI project.

In addition, the PI plans to 1) integrate the research findings into existing undergraduate and graduate courses in the Department of Civil and Environmental Engineering at the University of Utah and 2) develop and deliver outreach activities based on computer animations to demonstrate, for example, how contaminated water affects water quality in receiving water bodies.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.