ERI: Dynamic membranes in anaerobic wastewater treatment systems: Enhancing mitigation of emerging microbial threats to promote safe water reuse

Anerobic membrane bioreactors (AnMBRs) are providing new opportunities to design, build, and deploy a new generation of treatment processes that can recover clean water from wastewater while generating energy (biogas) and/or valuable products such as medium-carboxylic acids. AnMBRs combine membrane filtration (microfiltration or ultrafiltration) with anaerobic digestion in specially designed bioreactors.

Anaerobic dynamic membrane bioreactors (AnDMBRs) have emerged as promising alternatives to address the shortcomings of current AnMBRs including low flux, high capital and operating costs, and high propensity for membrane fouling. In AnDMBRs, in-situ formed biofilms on stainless-steel meshes (or woven/nonwoven fabrics) with pore sizes ranging from 5-200 microns provide the filtration media thereby circumventing the need to use commercial microfiltration or ultrafiltration membranes.

The overarching goal of this ERI project is to evaluate the effectiveness of AnDMBRs to remove pathogenic bacteria, genes, and other biomarkers associated with the spread of antibiotic resistance with the goal of producing water effluents that are safe for agricultural reuse. The successful completion of this project will benefit society by advancing fundamental knowledge on the use of AnDMBRs to enable the sustainable and safe reuse of rural wastewater for crop irrigation.

Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student and two undergraduate students at the New Mexico Institute of Mining and Technology.

Anaerobic membrane bioreactors (AnMBRs) combine membrane separation with anaerobic digestion to produce a high-quality effluent suitable for agricultural reuse. In anerobic dynamic membrane bioreactors (AnDMBRs), in-situ formed biofilms on low-cost porous substrates (e.g., stainless-steel meshes or woven/nonwoven fabrics) serve as dynamic membranes and filtration media.

Recent studies have shown that the biofilms that form on membrane surfaces in AnMBRs can enhance effluent water quality and aid in the removal of pathogenic bacteria and emerging biological contaminants. However, it is still unclear if the biofilms of AnDMBRs can maintain similar benefits for the removal of pathogenic bacteria, genes or other markers associated with antibiotic resistance.

This ERI project will address this critical knowledge gap. The specific objectives of the research are to 1) Quantify the concentration and abundance of antibiotic-resistant bacteria (ARBs), antibiotic resistance genes (ARGs), and other relevant gene transfer elements in AnMBR system effluents; 2) Establish a baseline for assessing the abundances of both intracellular and extracellular ARGs in AnMBR system effluents during the treatment of real and representative rural wastewaters; and 3) Evaluate the effectiveness of AnDMBRs to remove ARBs and ARGs during the treatment of rural wastewaters.

The successful completion of this project has the potential for transformative impact through the development of new fundamental knowledge to advance the design and deployment of more efficient and cost-effective technologies for the sustainable and safe reuse of wastewater for agriculture and farming in rural communities. To implement the education and outreach activities of the project, the Principal Investigator (PI) plans to leverage existing programs at the New Mexico Institute of Mining and Technology such as the K-12 outreach program, the STE2M summer experience for high school students, and the Upward Bound Math and Science program for local high school students to communicate the outcomes of the proposed research and engage the local community on water management and reuse.

This project is jointly funded by the CBET Environmental Engineering program and the Established Program to Stimulate Competitive Research (EPSCoR).

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.