Built on years of successful collaboration, Microbial Insights (MI) maintains working relationships with a variety of leading companies that develop and provide amendments like electron donors, electrons acceptors, and bioaugmentation cultures. MI is a privately held woman owned business, not owned by a consulting firm, product vendor, or investor conglomerate. As an independent laboratory committed to providing unbiased, high-quality analysis, we are trusted by product companies and their clients alike for data-driven product validation. This month, we spotlight the In Situ Microcosm (ISM) study—a powerful, practical tool for evaluating remediation performance under real aquifer conditions. ISMs provide clear, defensible insight into how products actually perform in the field, helping stakeholders make confident, science-backed decisions.
In Situ Microcosm Studies
An ISM study is performed to assess multiple remediation options including MNA, biostimulation, and bioaugmentation. An ISM assembly is a group of individual microcosm units, each representing a different treatment strategy. Each ISM unit contains passive samplers that provide the chemical, geochemical, and microbial data. Following in-well deployment, the ISM units are retrieved, and the passive samplers are shipped to MI for analysis to determine the impact of each treatment option on contaminant concentrations, daughter product formation, geochemistry, and concentrations of microorganisms and functional genes of interest.
Key Benefits of an In Situ Microcosm Study
- Cost effective: Study design allows for the simultaneous evaluation of multiple remediation options in the field for a fraction of the cost of a pilot test.
- Multiple lines of evidence: Chemical, geochemical, and microbial samples are collected from each unit to assess the effectiveness of the treatment options.
- In situ: Unlike lab bench studies, ISMs are deployed in monitoring wells and exposed to the subsurface conditions occurring at the site.
- Turnkey: Microbial Insights procures all amendments and bioaugmentation cultures from the vendors of your choice, and they are prepped and shipped along with the ISM units for easy field deployment. At the conclusion of the study, the interpretive report highlights key observations and summarizes all analytical results.
Cost Effective Remedy Selection at a Chlorinated Solvent Site
An ISM study was performed at a site contaminated with chlorinated ethenes and methanes where there had been concern about failures in on-site permeable reactive barriers (PRBs). A carbon + ferrous iron substrate had been injected in the past along with two different microbial cultures, but one culture appeared to be more compatible with the PRBs. The goal for the ISM study was to determine the strategy for the next injection event by identifying the amendment that best complements bioaugmentation and produces rapid effects. The ISM study was designed to evaluate four different conditions as shown in Figure 1.
Results: Contaminant analysis indicated daughter product formation in all four units (Figure 2). The Electron Donor + ZVI unit had the lowest total CVOCs and the highest ethene concentration, suggesting enhanced biodegradation of chlorinated ethenes and methanes relative to the other treatment conditions.
The geochemical data demonstrated that volatile fatty acids were higher in the treated units compared to the unamended control, indicating that microorganisms were fermenting the electron donor amendments in the treated units.
QuantArray®-Chlor analysis showed that Dehalococcoides concentrations exceeded the 104 cells/bead threshold in all four units, including the unamended control. These results suggest that a generally effective rate of complete chlorinated ethene degradation is possible even without bioaugmentation. Dehalobacter DCM and chloroform reductase genes were present in the three treated units but were below detection in the control unit, indicating that the genetic potential for chlorinated methane biodegradation was highest in the treated units.
Decision: Based on the ISM results, site managers selected the electron donor + ZVI amendment combination for the next injection event. The multiple lines of evidence collected clearly indicated that within the study period the electron donor + ZVI amendment created reducing conditions which stimulated both chlorinated ethene- and methane-degrading microorganisms, resulting in enhanced biodegradation of CVOCs.
ISM studies are highly versatile and can be tailored to evaluate a wide range of treatment strategies and contaminants. Critically, they also allow you to assess whether a bioaugmentation culture will survive and perform in situ before committing to full scale deployment, potentially saving thousands of dollars in ineffective treatments.
Whether you’re validating a product, optimizing a remediation strategy, or reducing uncertainty before moving to the field, an ISM study delivers actionable insight you can trust. Let MI help you make the right decision with confidence. Contact us at 865-573-8188 or [email protected] to discuss an ISM study or explore additional product evaluation solutions.
