You’re on the beach, the phone finally silent — until it isn’t.
When mechanical systems go down, the phone chain starts: your client calls you, and if you’re on vacation, you have to call someone to get the system up and running. Systems have their place — and that place is last resort!
RPI’s BOS and CAT products are in-situ platforms that, once installed, perform without interruption, day and night, weekends and holidays, moving your site inexorably toward meeting your defined goals.
In the end, remediation is just fancy “taking out the garbage”. Why futz around with it? Install something proven, that does not break, and that does not stink for that matter.
So go ahead — answer the phone because you want to, not because you have to.
Eliminating Microbial Homelessness
Successful in situ bioremediation requires more than electron donors, acceptors, nutrients, or added microbes. It also requires a place for microbes to live.
Most aquifer microorganisms are attached to sediment rather than suspended in groundwater, and attached communities are more abundant and metabolically active than planktonic populations (Alfreider, 1997) (Griebler, 2002). Attachment concentrates biomass, retains extracellular enzymes, and establishes stable redox microenvironments that enable syntrophic exchange (Holm, 1992), while forming synergistic communities capable of processes individual species cannot accomplish alone (Fredrickson, 2001) (Beveridge et al., 1997) and providing protection from toxicants, washout, and predation (Caron, 1987)(Matz, 2008).
The preference is measurable. Capozzi et al. (2019) found that dehalorespiring bacteria colonized GAC/PAC blended activated carbon at roughly four times the biofilm coverage seen on sand — 20.2% versus 5.5% — reaching up to 15 billion cells per gram of material. This holds for both GAC and PAC. Meynet found that granular activated carbon supported the highest microbial cell densities in a three-year field study, while powdered activated carbon maintained an equivalent abundance of PAH-degrading genes without harming the native community. Bonaglia found that powdered activated carbon increased microbial diversity and boosted anaerobic naphthalene degradation by up to 96%, an effect attributed to activated carbon facilitating direct interspecies electron transfer between degrading microorganisms. Colloidal and microscale activated carbon are newer to the field, and comparable direct demonstrations remain limited in the published literature.*
RPI products such as BOS 200+® and CAT 100 are designed to provide subsurface microorganisms somewhere to live, not just something to eat. The rough surfaces, protected crevices, and interconnected mesopores of GAC/PAC provide physical habitat. Their adsorptive capacity concentrates contaminants, nutrients, and electron donors and acceptors in biofilm; and their electrical conductivity supports direct electron transfer between neighboring organisms.
RPI does not simply supply amendments to the subsurface — we engineer habitat that enables microbial communities to establish, persist, and perform.
*In my own laboratory tests, PAC and GAC showed clear initial biofilm formation in 72 hours, while CAC developed no observable biofilm over the same period.
References
- Alfreider, A. K. (1997). Groundwater samples do not reflect bacterial densities and activity in subsurface systems. Water Research, 31(4), 832-840. doi:https://doi.org/10.1016/S0043-1354(96)00311-9
- Bonaglia, S. B. (2020). Activated carbon stimulates microbial diversity and PAH biodegradation under anaerobic conditions in oil-polluted sediments. Chemoshpere, 126023. doi:10.1016/j.chemosphere.2020.126023
- Caron, D. (1987). Grazing of attached bacteria by heterotrophic microflagellates. Microbial Ecology, 13(3), 203-218.
- Fredrickson, J. F. (2001). Subsurface Microbiology and Biochemistry. New York: Wiley-Liss, Inc.
- Griebler, C. M.-K. (2002). Distribution patterns of attached and suspended bacteria in pristine and contaminated shallow aquifers studied with an in situ sediment exposure microcosm. Aquatic microbial ecology, 28, 117-129.
- Holm, P. N. (1992). Importance of unattached bacteria and bacteria attached to sediment in determining potentials for degradation of xenobiotic organic contaminants in an aerobic aquifer. Applied and Environmental Microbiology, 58(9), 3020-3026. doi:doi/pdf/10.1128/aem.58.9.3020-3026.1992
- Matz, C. W. (2008). Marine Biofilm Bacteria Evade Eukaryotic Predation by Targeted Chemical Defense. PLoS ONE, e2744. doi:doi.org/10.1371/journal.pone.0002744
- Meynet, P. H. (2012). Effect of Activated Carbon Amendment on Bacterial Community Structure and Functions in a PAH Impacted Urban Soil. Environmental science & technology, 5057–5066. doi:doi.org/10.1021/es2043905
Let’s Play this Game One More Time with a Hint: Last Month’s Newsletter
What is the purpose of this tool? The hint from last month’s newsletter is that it is some tool for repairing clocks.
This is a mainspring hole punch, used by clockmakers to punch the attachment hole in a clock mainspring.
There’s an important lesson hidden in this simple tool. Before the hole is punched, the end of the spring must first be heated to reduce its brittleness. Otherwise, the spring is likely to crack. After punching, the spring must be reheated and oil-quenched to restore its properties. Simply owning the tool is not enough; you must know how and when to use it.
The same principle applies to environmental remediation.
The injection equipment, delivery systems, and specialized tools developed by RPI and deployed by the RPI Group companies are unmatched in the industry. While others have attempted to copy aspects of our equipment, possessing similar-looking equipment does not confer the knowledge and experience required to use it effectively.
Over decades of fieldwork, we’ve learned not only how to build the tools, but also how to apply them under the wide range of conditions encountered in real-world remediation projects. Experience, judgment, and attention to detail are what transform a tool into a successful outcome.
