Water Resources Research Act Program

Details for Project ID HI_2024_Wang

Harnessing bacteria-microalgae interactions for enhanced onsite wastewater treatment

Institute: Hawaii
Year Established: 2024 Start Date: 2024-09-01 End Date: 2025-08-31
Total Federal Funds: $42,000 Total Non-Federal Funds: $42,000

Principal Investigators: Zhiyue Wang, Marek Kirs

Project Summary: One-fourth of the U.S. population reside in unsewered households that rely on onsite wastewater systems for treatment and disposal. Legacy systems without designed capacity for treatment, such as cesspools, pose serious threats to water resources. The problem is exacerbated in coastal regions like Hawaii, where untreated wastewater in cesspools infiltrates into groundwater aquifers imperiling public health and local ecosystems. Current cesspool replacement technologies, including septic tank and aerobic treatment unit, are either inadequate in its nutrient removal capability or restricted by the high energy demand and maintenance requirement. Novel solutions are needed for low-cost, efficient, resilient, and sustainable onsite treatment systems. Algae-bacteria systems showed promising traits that can be utilized to develop passive aerobic treatment processes with low maintenance and efficient nutrient removal. Nevertheless, maintaining a robust and stable microbial and algal community dynamics is challenging, especially under complex operational conditions for municipal wastewater treatment. Mathematical modeling is therefore chosen in this study to unravel cross-species interactions and guide system design. Conventional mechanistic models use a black box approach and are limited in complexity and accuracy when used to characterize population dynamics of individual species or a group of species with similar functions. A new approach is proposed integrating bioinformatics with mechanistic models, enabling quantitative predictions of key microorganisms involved in nutrient removal and testable simulation results under various operating conditions. There are three main objectives for integrated research and education in this study: (1) Establish a mathematical model with integrated bioinformatics, nutrient flux, and material exchange for a bacteria-microalgae system; (2) Validate model predictions with a prototype system for onsite wastewater treatment; and (3) Develop a graduate-level course on mechanistical modeling and recent developments. The established model will be calibrated with experimental results from batch incubations of microalgae-bacteria co-culture in the laboratory, after which performance data from a pilot-scale system will be used to validate the model. Research findings will be incorporated into the new course developed, focusing on hands-on learning of mathematical modeling and environmental microbiology techniques.