A water treatment plant (WTP) using conventional air stripping technology and carbon polishing to remove chlorinated volatile organic compounds (CVOCs) before discharging the treated groundwater was in operation for over 12 years. The WTP was efficient at treating CVOCs to regulatory levels. However, rising operation and maintenance (O&M) costs, e.g., chemicals, electricity, and labor, necessitated an alternative for treating groundwater contaminated with CVOCs. The alternative had to remove CVOCs to below detection limits (BDL) for incorporation into the Monitored Natural Attenuation (MNA) remedy component, decrease O&M costs, and meet regulatory approval.
A series of field pilot tests, based on air stripping/carbon polishing technology, were designed to evaluate a Passive Aeration System (PAS) to demonstrate that CVOCs could be successfully removed to BDL. Based on the successful pilot tests, a full-scale test was implemented and demonstrated that the PAS could consistently remove CVOCS to BDL at flows up to 10 gallons per minute
Removal efficiencies and CVOC speciation from the pilot tests indicated that the PAS technology was a viable alternative to the conventional WTP. Analytical results from the full-scale test showed consistent analytical results of CVOCS that were BDL. The PAS was approved by the U.S. EPA and the Oklahoma Department of Environmental Quality as a permanent remedy modification to replace the conventional WTP.
The electricity savings alone using the PAS amount to more than $20,000 per year. The PAS also employs air stripping and polishing steps but utilizes the sun and wind to remove the CVOCs without electricity or chemicals and with minimal O&M costs.
