Question by Gary Canny
I was wondering if anyone knows of suppliers of Fenton's reagent in Europe
more specifically in Ireland or someone who is willing to supply the reagent
to Ireland.
I was looking to apply the reagent to a site we have which has been
contaminated with diesel, to an area of contaminated clay material situtated
beneath the foundation of a house which cannot be excavated due to the
structure of the house.
Has anyone used Fenton's reagent in such a situation, is there any problems
I should look out for and are there any known techniques out there for the
deliver of such a reagent into a clay material.
Answer
I just found the following at http://www.clu-in.org/products/tins/
IN-SITU GROUNDWATER REMEDIATION BY FENTON'S REAGENT INJECTION: A CASE STUDY
Smith, M., Wardrop Engineering Inc., Winnipeg, MB, Canada.
Canadian Reclamation, p 4-8, Winter-Spring 2005 [OSTI: DE20607332]
A quarter-hectare site that once hosted a bulk fuel facility was heavily contaminated by a variety of released hydrocarbons. Because the site is underlain by an unconfined aquifer used for drinking water, the cleanup goals aimed to meet Health Canada's stringent guidelines for Canadian drinking water quality. The cleanup was undertaken using in situ chemical oxidation, which involves the injection of chemical oxidants into the subsurface for direct treatment. Fenton's reagent, a combination of hydrogen peroxide and iron sulphate, was used to take advantage of the oxidizing strength of the hydroxyl radicals. Injection of the reagent took place during three separate events in August 2003 and July and September 2004. Ground-water samples from a total of 11 on- and off-site wells were tested for BTEX (benzene, toluene, ethylbenzene, xylenes) and total volatile hydrocarbons immediately prior to each injection. The injections were constantly monitored to prevent excessive gas evolution through the site surface. Maximum total BTEX concentrations in excess of 9.0 mg/L in August 2003 were reduced to below 0.4 mg/L by September 2004. As of September 2004, all off-site wells complied with the standards prescribed by the guidelines for Canadian drinking water quality. Bacterial population increased dramatically over the injection period, suggesting that aerobic respiration has been an important contributor in the degradation of petroleum constituents in the soil and the ground water.
Further, I think the Fentons reagent should be prepared immediately before injection at place.
Answer by John Haselow
there are a number of options available.
Classical Fenton's chemistry involves a transmission metal (typically ferrous
iron) and hydrogen peroxide under acidic conditions.
You should be able to purchase hydrogen peroxide, ferrous sulfate (for
example), and some inorganic acid in Ireland.
There are other options that involve calcium peroxide, chelated iron, etc
that can be used also.
We have used a mixture of sodium persulfate and calcium peroxide also for
residential applications. It is a lot safer to work with.
If you decide to do this yourself with Fenton's chemistry, be extremely
careful, because you are bringing a strong oxidant in contact with fuel and
heat, which can lead to unsafe conditions if you don't know what you are
doing.
Steve Short
Due to its extreme instability/reactivity Fentons Reagent cannot as such be
prepared for sale and supplied.
In fact Fentons Reacgent is simply hydrogen peroxide (of various grades) to
which a ferrous chloride or sulfate solution is dosed just prior to
injection. The ferrous ion catalyses the (free radical) oxidation.
You will need to separately source the peroxide and the FeCl2 solution and
set up some sort of dosing/mixing arrangement.
Hendrik van Herzeele
See www.insitu.nl
Xingzhi Wu
I am doing research on in situ bioremediation of PCE contaminated soil. For
low hydraulic permeable clay, it is very hard to deliver reagent into it. On
the other hand, as the clay was contaminated, there should be some pathway
for diesel transport into the clay, such as fracture. Find the pathway, and
inject the reagent through it. Otherwise, try electroosmosis flow injection.
The reagent is very active and may not stay long time in soil.
Fred Heyrich
Fred Heyrich
As with most inquiries, etc. I probably Need a little more information before I shoot my mouth off.
Q.: pH of Diesel+ and soil. If alkaline, no problem, I can tell you how or send you A VERY modified Fenton Redox effective in Alk. pHs. Is the house occupied? Sounds like the amount of soil to be remediated is relatively small anyway, so I'll shoot my mouth off anyway! Also I have been persuaded that ""finish" remediation should be biological. Also, how the heck did diesel fuel get there? It would help if there had been an analytical concn., C-chain, etc. Using a consortium of bacteria would work without the Fenton R. (VERY) modified but would produce odor and would be considerably slower.
Another alternate would be to use an absorbant inoculated with surfactant and consortia of bacteria, (non-paths)and other agents which degrade and emulsify HCs, which would :
1. effectively encapsulate the HC liquids, [mixing required] emulsify the HC into fatty acids and triglycerides of fatty acids and.2. the consortium of bacteria, yeasts and molds, begin degradation further, in about 2 hours; Est. time to be reduced to 100 ppm is about 2 weeks. The absorbant bacteria need about 30 % moisture during that time. The times I have remediated diesel containing oxyginating additive as well as usual BTEX under pumping stations, near foundation levels, the whole project took about 2 weeks to satisfy levels which were analyzed to be ND. I would most probably recommend the latter remediation since you appear to be not very familiar with Fenton reactions. If interested I would need to know the cubic yards of contaminated soil and the approximate concentration. Incidentally this also worked in a house crawl-space where the drain had collapsed and considerable grease and feces had spilled. The absorbant + 30% moisture was mixed together by the plumber. The odor was abated in about 3 days [and they moved back in] and it took about 2 weeks to finish. The absorbent and degraded stuff were left in place and an additional layer of absorbent was placed at the request of the homeowner "just in case the new drain had a problem". Make a date to recheck, in about 30 days, I did and we had a damn crop of mushrooms. [if that happens I'll tell you how to kill them out. [Some of our composters sell the degraded stuff for potting soil].
James Cashwell
We've just completed a similar project where Fenton's Reagent was used
to treat saturated soils impacted with residual coal tar (PAHs and BTEX)
at concentrations as high as 30,000 mg/kg. The impacts were found under
an old house, and we installed directional injectors.
Fenton's should work well in your situation, but I suggest that you
consider the installation of vent wells around the perimeter of the
house. If you have significant concentrations of diesel present, the
oxidation process will result in a significant amount of gas (CO2 and
oxygen). The site will need to breath if the soils are too tight or the
house foundation is too large to allow for sufficient off-gassing.
Otherwise, your injection rate will likely decrease and your treatment
effectiveness may be limited.
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