The International Information Center for Geotechnical Engineers

Soil Remediation Techniques: Examination of In Situ Chemical Oxidation


2. Background

In Situ Oxidation is based on oxidation methods originating from drinking water and wastewater treatment as early as 1930. The development and use of ISCO to remediate contaminated soil is fairly young and stemmed from on site or ex situ treatment in reactor systems (Tsitonaki, 2008). Watts et al.(1990) recognized that “a large number of hazardous waste disposal and spill sites are characterized by surface soils contaminated with chemicals that are resistant to degradation” and an alternative to bioremediation needed to be studied ( Watts et al., 1990). The first reports discussing ISCO treatment were published in the 1990s and by the middle of the decade companies were already offering ISCO services (Watts & Teel, 2006). 

The first of ISCO processes to be investigated in laboratory research and fully developed was catalyzed H2O2 propagations (CHP), also known as modified Fenton’s reagent. Next, use of ozone sparging and permanganate treatment became common, and in the early 2000s persulfate became another oxidant option for ISCO remediation (Watts & Teel, 2006). ISCO has become widely used in the US with permanganate leading as the most common oxidant used in application. Persulfate is emerging as a successful oxidant with increasing field applications and a variety of implementation approaches (Tsitonaki, 2008). In oxidative treatment systems, numerous reactions could potentially occur, including acid/base reactions, adsorption/desorption, dissolution, hydrolysis, ion exchange, oxidation/reduction, precipitation, etc (Hueling & Pivetz, 2006). 

ISCO has been used to remediate thousands of hazardous waste sites in the United States and is considered the fastest growing subsurface remedial technology nowadays (Hueling & Pivetz, 2006). As for any other remediation approach, the following steps need to be followed: 1) Site characterization (soil and contaminants), 2) Risk assessment (present or potential, it will determine if site will be remediated or not) and lastly 3) Selection of effective remediation technique.

The following sections of this document will further discuss this soil and groundwater remediation technology. 

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