Question by Bob Brooks
Is anyone familiar with the use of surfactants to aid in bioremediation of clay.
I have been investigating the possibility of using a surfactant for soil washing. Many of the companies that sell these products make some fairly exaggerated claims. One chemist from a surfactant company suggested using Liquid Humus to prep the clay followed with surfactant and microbes.
Digging up the contamination on site is preferred but not practical due to numerous utilities present.
If anyone has any experience or knowledge of surfactants, I would appreciate the advice.
Answer
what is your purpose - bioremediation or soil washing or one of several combinations of the two?
Further, the chemical composition of the contaminant and distribution/binding of the contaminant is of great importance!
For soil washing (unless the contamination is not present as separate phase or highly volatile) the high surface area of clay will result in need of high surfactant concentrations to achieve efficient removal. Even in case of a tailor-made surfactant combination you will need at least a 1 - 2 % aqueous solution.
Soil washing as a pretreatment step might ease subsequent bioremediation.
Addition of surfactants in low concentration might work in some cases to enhance bioremediation provided there are capable biodegraders in place.
Answer by Fred. J. Heyrich
Answer
what is your purpose - bioremediation or soil washing or one of several combinations of the two?
Further, the chemical composition of the contaminant and distribution/binding of the contaminant is of great importance!
For soil washing (unless the contamination is not present as separate phase or highly volatile) the high surface area of clay will result in need of high surfactant concentrations to achieve efficient removal. Even in case of a tailor-made surfactant combination you will need at least a 1 - 2 % aqueous solution.
Soil washing as a pretreatment step might ease subsequent bioremediation.
Addition of surfactants in low concentration might work in some cases to enhance bioremediation provided there are capable biodegraders in place.
Answer by Fred. J. Heyrich
I have been encountering clay, cleche, aggregae and the mix, sometimes just sand which is a distinct pleasure to work in. On the compacted sils, following a lead from the Aussies, I use a modified Fenton Reagent, following a fairly dilute application of a wetting, surfactant/penetrating agent with some sodium silicate to reduce foaming and try to be patient for about 2 days. Per monitor hole [now also a treatment hole] softens and partially slurries the clay/cleche
to an area about 4 -6 feet, depending on just how compact the "soil" is. I have also, when I didn't have reagents handy used vinegar and bicarbonate mix. KIn each case, pull up samples and use them on the spot [lab-scale] to determine strengths. Then I added our consortium of bacteria, molds and yeasts and fungi (I know the difference). We sample about 3 feet away from the previous monitor hole, to what ever depth the hole was originally. Modified Fenton also serves to gradually release Oxygen for the consortium.
My proportions are millimole.
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