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Confidential Client
Ontario, Canada
Project
Pilot-Scale demonstration on soil containing
phenoxy-acid herbicides (2,4-D, and 2,4,5-T), and
other chlorinated pesticides (DDT, DDD, and
DDE)
Summary
The application of DARAMEND® served to
reductively de-chlorinate, and subsequently
mineralize the chlorinated herbicides and
pesticides.
The Challenge
Treatment of 350 tons of soil impacted by
phenoxy-acid herbicides (2,4-D, and 2,4,5-T), and
other chlorinated pesticides (DDT, DDD, and
DDE).
The Solution
The treatment process involved the application of
DARAMEND® to a 60 cm thick layer of soil
within a treatment cell. Due to the volatile and
highly toxic nature of the phenoxy-acid
herbicides the treatment cell was covered with a
polyethylene clad greenhouse. Negative pressure
was maintained within the greenhouse by
continuously drawing air from the greenhouse and
discharging it through a granular activated
carbon filter. Soil undergoing treatment was
subjected to several treatment cycles and was
irrigated to 90% of the soil water holding
content at the start of each treatment cycle.
The Result
The concentrations of the target contaminants,
2,4-D, 2,4,5-T, and DDT, were reduced by over
96%, 84%, and 91% respectively (Figure 1).
Initial mean concentrations of 97.7 mg/kg, 8.1
mg/kg, and 54 mg/kg, were reduced to 3.6 mg/kg,
1.3mg/kg, and 4.7mg/kg, respectively.
The Cost
The estimated treatment cost for the full-scale
application of DARAMEND® bioremediation at
this site, which would have involved the
treatment of 35,000 tons of similarly
contaminated material, was approximately
US$127.00/ton. The cost associated with this
project is slightly elevated when compared with
most similarly sized projects due to the
extremely toxic and semi-volatile nature of the
contaminants, and consequently, the extraordinary
steps required to ensure workplace safety and to
prevent any environmental impacts during
treatment.
The Timeline
Treatment of this material to the above levels
required the application of nine treatment
cycles. At this site, each treatment cycled
required approximately one month, for a total
active treatment period of approximately 9
months. Although one month was required per cycle
during this pilot-application, improvements made
in the application procedures for this technology
have reduced the time required per cycle to an
average of about 10 days. Using improved
techniques Adventus estimates that the same level
of treatment could now be accomplished in 3 to 4
months.
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Figure 1. Effect of
DARAMEND® treatment on concentrations of
2,4-D, 2,4,5-T, DDT, DDD, DDE during
pilot-scale demonstration at a site in Ontario,
Canada.
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