Comprehensive characterization of aerobic groundwater biotreatment media

• Published in: Water research (Oxford) Vol. 230; p. 119587
• Main Authors: Keithley, Asher E., Ryu, Hodon, Gomez-Alvarez, Vicente, Harmon, Stephen, Bennett-Stamper, Christina, Williams, Daniel, Lytle, Darren A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.02.2023
• Subjects: Ammonia; Arsenic - chemistry; Biofilter; Biological treatment; Carbon; Groundwater; Groundwater - chemistry; Iron - metabolism; Manganese; Manganese - chemistry; Water Pollutants, Chemical - chemistry; Ammonia; Biological treatment; Groundwater; Biofilter; Manganese
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2023.119587

•Aerobic biofilters effectively treated ammonia, iron, manganese, and/or arsenic.•Ammonia impacted microbial communities more than iron, manganese, or arsenic.•Comammox Nitrospira detected in biofilters treating < 0.01–3.34 mg/L NH3-N.•Heterotrophic bacteria may be important in nitrifying biofilters.•Slight negative correlation between manganese oxidase and water concentrations. Aerobic biotreatment systems can treat multiple reduced inorganic contaminants in groundwater, including ammonia (NH3), arsenic (As), iron (Fe), and manganese (Mn). While individual systems treating multiple contaminants simultaneously have been characterized and several systems treating one contaminant have been compared, a comparison of systems treating co-occurring contaminants is lacking. This study assessed the treatment performance and microbial communities within 7 pilot- and full-scale groundwater biotreatment systems in the United States that treated waters with pH 5.6–7.8, 0.1–2.0 mg/L dissolved oxygen, 75–376 mg CaCO3/L alkalinity, < 0.03–3.79 mg NH3-N/L, < 4–31 µg As/L, < 0.01–9.37 mg Fe/L, 2–1220 µg Mn/L, and 0.1–5.6 mg/L total organic carbon (TOC). Different reactor configurations and media types were represented, allowing for a broad assessment of linkages between water quality and microbial communities via microscopy, biofilm quantification, and molecular methods. Influent NH3, TOC, and pH contributed to differences in the microbial communities. Mn oxidase gene copy numbers were slightly negatively correlated with the influent Mn concentration, but no significant relationships between gene copy number and influent concentration were observed for the other contaminants. Extracellular enzyme activities, community composition, and carbon transformation pathways suggested heterotrophic bacteria may be important in nitrifying biofilters. Aerobic groundwater biofilters are complex, and improved understanding could lead to engineering enhancements. [Display omitted]