Enhancing Water Treatment Using Nitrate-Metabolizing Microbes

Problem: Wastewater treatment plants across Minnesota can effectively remove organic carbon and phosphorus from wastewater, and convert toxic ammonia to less toxic nitrate. However, they still discharge large amounts of nitrate to public waterways, which may cause unwanted algae growth and local ecosystem damages.

Solution: Some microbes remove nitrate from water through a process called denitrification, which turns nitrate into gas phase nitrogen. While this process usually occurs in the absence of oxygen, recent research shows that some microbes can denitrify in the presence of oxygen (called aerobic denitrification). Aerobic denitrification should be compatible with current wastewater treatment technologies. However, it has not been tested as a water treatment solution to remove high concentrations of nitrate. Ishii’s team will explore and assess the efficacy of specific microbes in reducing nitrate concentrations within contaminated water. The lab-based approach will mimic wastewater treatment system conditions to evaluate actual scenarios.

Impact: The optimization of wastewater treatment systems to reduce nitrate can only progress after microbial communities are better understood and characterized. Long-term use of these optimized systems should reduce nitrate impairment of local ecosystems and help Minnesota meet nutrient reduction goals.