User:Snehakrishna/ISCO

In situ chemical oxidation (ISCO) is an environmental remediation technique used to remediate soil and/or groundwater by reducing the concentrations of targeted environmental contaminants to acceptable levels. ISCO is accomplished by injecting or otherwise introducing strong chemical oxidizers directly into the contaminated medium (soil or groundwater) to destroy chemical contaminants in place. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation. Common oxidants are persulfate, modified Fenton's Reagent, ozone, [[tri-atomic oxygen (O₃), sodium permanganate and potassium permanganate. Among the organic chemicals amenable to remediation by ISCO are chlorinated solvents such as trichloroethene and tetrachloroethene), and gasoline-related compounds like benzene, toluene, ethylbenzene, MTBE, and xylenes). Some contaminants can be made less toxic through chemical oxidation.

The effectiveness of the oxidation is contingent on the site lithology, the residence time of the oxidant, the amount of oxidant used, the presence of oxidizing materials other than the targeted contaminant, and the degree of effective contact between the oxidant and the contaminant(s). Some ISCO compounds (particularly Fenton's Reagent) can react aggressively with organic contaminants and must be used with care. Oxidants such as Permanganate and Fenton's Reagent are delivered as water-based solutions. Ozone is delivered (sparged) as a gas in either a dry air or oxygen carrier gas. Specialized equipment is required for in-situ oxidation via ozone gas injection.Ozone Eqiuipment for In-situ Oxidation

The primary delivery mechanism for ISCO is through perforated, hollow metal rods hammered with a mechanical hammer into the ground by "direct-push" drilling methods, or by injecting ino wells installed using hollow stem auger, rotary drilling methods. One advantage of injection wells is that they can be used for multiple applications of the oxidant material, while direct push injection techniques are generally quicker and less expensive. Injection wells for ozone are typically constructed of a 1-2" stainless-steel screen set in sand pack, grouted to the surface using a combination of cement and bentoine clay.

Often, a field pilot study must be performed to determine injection parameters and well spacing. The soil and groundwater are tested both before and after oxidant application verify the effectiveness of the process. Monitoring of gases given off during oxidation can also help determine if contaminants are being destroyed. Elevated levels of CO₂ are an indicator of oxidation.