In Situ Chemical Reduction (ISCR) for Removal of Persistent Pesticides; Focus on Kepone in Tropical Soils
| Country: France
| Start Date:
Project Type: Demonstration
| Contract Number:
| Organisation Type:
Consultancy, contractor or other service provider
Contaminated land-->Contaminated land overview
| Project objectives:
The global use of organochlorine pesticides (OCPs) such as Kepone, Lindane, DDT, Dieldrin, Chlordane, and Toxaphene has resulted in long-term soil impacts
at many sites. Given the potential risks to human health and the environment, some OCP-impacted sites require treatment. In certain cases, the “dig-and-dump”
approach is not practical due to magnitude of the problem, access issues, and/or resource constraints. Here, “bioremediation” can be used to treat the soil
on site, often at lower costs, and certainly with lower generation of greenhouse gases. Unfortunately, most OCPs are not amenable to conventional bioremediation
technologies, hence they persist over time.
Use of the insecticide Kepone on banana plantations until the mid-1990’s in the French West Indies islands has led to major environmental impacts. These
include damage to drinking water supplies, bans on vegetables, fish and sea food consumption and commercialization, and increased occurrence of prostate
cancer in Guadeloupe. Kepone is widely considered as an extremely persistent neurotoxic organochlorine insecticide, with no evidence of environmental
attenuation. Natural, very slow leaching from the impacted soils to the water compartment will take centuries to significantly reduce current Kepone soil
concentrations. The study presented here was financed by the French Ministry of Environment.
The term ISCR is used to define the combined effects of stimulated biological oxygen consumption (via “fermentation” of complex organic carbon sources),
reduction with reduced metals, and the corresponding enhanced decomposition reactions that are realized at the lowered redox (Eh) conditions. In brief,
the ZVI oxidizes to
form ferrous iron and releases electrons in the process. The organic carbon is consumed by microorganisms that are indigenous to the soil, resulting in release
free electrons. These electrons transferred to the OCPs result in the removal of chlorine
from the compound’s structure (reductive dechlorination); ultimately, complete destruction of the pesticides can occur. Most soils can be effectively
treated in a reasonable time frame (e.g., from 4 to 8 weeks) using standard agricultural machinery at a price typically less than €15 per tonne of soil treated.
| Achieved Objectives:
This case study summarizes implementation of the ISCR theory, followed by results on
technology validation tests for remediation of Kepone impacted soils (banana fields) from the French West Indies (Caribbean). Bench-scale studies with
spiked sand demonstrated rapid (< 2 weeks) and extensive degradation of Kepone: catabolites with up to 7 Cl removed were identified by GC/MS/MS. Extensive
validation of an analytical procedure involving the use of Kepone-13C as internal standard was conducted for the three soil types. Mesocosm (scale-up) studies
with tropical soils determined that treatment duration of 6 months resulted in 90% decrease in Kepone concentration for two of the major soil types, and 45%
for the third soil type. Significant effect of the treatment was observed on microbial biomass and activity, and genetic structure of the bacterial community.
Ecotoxicity tests and bioaccumulation studies will also be considered in the evaluation of the process. Recognized technology development needs include
insight into catabolite environmental fate/affect. Significant advances in
the biogeochemistry of OCP degradation are anticipated from basic research on microbiology and genetics of ISCR processes.
| Product Descriptions:
DARAMEND® in situ chemical reduction (ISCR) technology uniquely combines controlled-release carbon with a reduced metal such as zero valent iron (ZVI) or
zinc to yield a highly effective material for stimulating the complete degradation (no accumulation of
catabolic intermediates) of persistent organic compounds present in soil, sediment and
groundwater. DARAMEND is an advanced biological treatment technology for soil, sediment, and solid wastes contaminated with recalcitrant organic compounds.
This patented technology has been successfully applied to more than 9,000,000 metric tons of soil, sediment, and other wastes contaminated with polycyclic
aromatic hydrocarbons (PAHs), PCP, phthalates, chlorinated herbicides and pesticides, organic explosive compounds and wood preservatives at a variety
of industrial and military sites in the USA, Canada, Australia, Europe and China. Independent audits conducted by the US EPA and Environment Canada found DARAMEND
to be effective for the treatment of soils at wood preserving sites. DARAMEND has been successfully applied to soils containing organic explosive compounds
at US Navy and Army sites in Virginia, Iowa, New Jersey, Nevada, and Illinois. The technology is uniquely advantageous because it can often be applied without
excavation, generates no odors or leachate, and does not result in bulking. The use of DARAMEND can result in substantial cost savings and shorter remediation
schedules compared to traditional bioremediation processes, such as composting.
| Additional Information:
| Project Resources:
| Funding Programme(s):
| Link to Organisations:
BRGM - Geosciences pour une Terre durable (Geosciences for a sustainable Earth)
Environmental Protection Agency
Dr Jim Mueller
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