Onsite Carbon Regeneration with Chemical Recovery

Superfund Site Remediation

pilesThe National Institute of Environmental Health and Sciences (NIEHS) has awarded SBIR Phase I and Phase II grants totaling $1,120,000 to CHA Corporation to develop the microwave technology for Superfund Site Remediation. Under the NIEHS SBIR Phase I work, CHA Corporation built and field demonstrated a prototype microwave reactor system capable of regenerating saturated Granular Activated Carbon (GAC) on site and recovering chemicals from soil vapors.

The CHA Corporation conducted a two-month field demonstration at a soil remediation site designated IC 34/35/37 in what was formally McClellan Air Force Base (AFB), Sacramento, California. The field demonstration was also supported by the US Air Force Real Property Agency (AFRPA) and the URS Corporation.

The prototype microwave system operated for more than two months with no major operational problems. Thirteen cycles of adsorption and microwave regeneration were completed using two batches of GAC at 200 pounds each. The amount of liquid chemicals recovered indicates that microwave regeneration restores the original working adsorption capacity of GAC, thereby creating a continuous destruction and regeneration cycle.

Enhanced Recovery Inc. and CHA Corporation are currently combining microwave technologies developed by the two companies for contaminated site remediation. The microwave-enhanced soil vapor extraction is applied to increase the VOC removal rate from soils, which significantly reduces the time required for complete site cleanup. The on-site microwave carbon regeneration system is applied to recover or destroy VOCs in soil vapor, which eliminates the need for a large catalytic oxidizer that would produce secondary air pollutants and greenhouse gas. The microwave water treatment system is applied to treat ground water contained in the contaminated site without creating any air pollution or greenhouse gas. This combined microwave technology provides significant environmental benefits and cost savings.

Results from Extensive Field Testing

Under the NIEHS SBIR Phase II work, CHA Corporation designed and constructed a field mobile unit capable of reactivating 100 pounds GAC per hour. This mobile unit was transported and field demonstrated in May 2006 at the Site S of McClellan AFB. This mobile unit is of commercial size and ready to be used for removing and recovering VOCs from vented air streams. The two field tests demonstrated clearly that the microwave technology is a cost-effective commercial solution for recovering VOCs from a number of different sites. Using the field demonstration test results, technical and economic feasibility of the microwave technology was assessed. The results indicate that the onsite microwave regeneration with chemical recovery is the most economic method that can replace currently operating catalytic and high temperature oxidizers.

The microwave-enhanced soil vapor technology has been demonstrated at an abandoned gas station site in Atlanta, GA. A well was drilled to lower a 915 MHz microwave applicator. Microwaves were then applied at depths of 22-28 ft. A blower was used to extract the vapors from the extraction wells. The microwave-enhanced soil vapor extraction increased the VOC removal rate seven times compared with the conventional soil vapor extraction using air sweep only. Microwave run time totaled 57 days in which 1800 pounds of contaminants were removed, which is 7 times greater than 250 pounds estimated by using the vacuum air sweep only. Soil analysis results clearly show that contaminants contained in soil are almost completely removed and the site is completely restored for reuse. It took 82 days to remediate this site with the in-situ microwave technology. This suggests that the time required for complete restoration of a contaminated site could be reduced significantly by applying the in-situ microwave technology.

Using microwave technology is the economic method for the onsite carbon reactivation and enhancing soil vapor extraction, allowing for significant cost saving in the remediation of contaminated sites. Also, the microwave-enhanced soil vapor extraction will reduce the site remediation time significantly and the onsite microwave reactivation eliminates secondary air pollutants such as NOx and dioxins and reduces green house gas generation significantly. The onsite microwave reactivation technology combined with microwave-enhanced soil vapor extraction is the most economically feasible method for contaminated soil remediation.

Laboratory Air Pollution Control

In addition to our own NIEHS work, Montana State University (MSU) awarded CHA Corporation a mid-size grant totaling $590,000 to design, construct and field demonstrate a treatment facility to clean laboratory fume hood exhaust air. The goal of the project was to eliminate emissions from the planned EPICenter building to be constructed at the MSU campus in Bozeman, Montana. In 2001 CHA Corporation completed a two-month onsite test at the Safety & Risk Management facility at MSU. This test saw a successful performance from both the GAC (Granular Activated Carbon) adsorber and the microwave regenerator.