Use of Surfactant Modified Clay and Zeolite for Treatment of Perchlorate Contaminated Water

Perchlorate threatens the drinking water supplies of more than 20 million people in the United States and the number keeps growing. The cost of treating perchlorate and other emergent contaminants in drinking water using ion exchange resins, nanofiltration, and granular activated carbon (GAC) is a growing financial burden to many municipal and regional water boards. PLANTECO Environmental Consultants, LLC, has conducted preliminary testing of low-cost surfactant modified clay (SMC) and surfactant modified natural zeolite (SMZ). These unique “tailored” clays and zeolites show great promise as effective filtration media for removal of perchlorate from freshwater, brine solutions (produced during regeneration of ion exchange resins), and process wastewater. Further testing is needed to determine feasibility. The tailored clays developed by PLANTECO are produced from widely available natural raw materials that are significantly less expensive than ion exchange resins, GAC, and other products currently used to filter perchlorate from water. A very unique feature of the tailored clays and zeolites is that all perchlorate adsorbed onto the spent nonregenerable (load and toss) clay/zeolite is completely destroyed using a very low-cost proven biodegradation technique. The bioremediated SMC or SMZ is rendered nonhazardous, which eliminates potential future liability and minimizes disposal costs. This 6-month project will evaluate the relative feasibility and performance of uniquely formulated SMC and SMZ for the sustained low-cost treatment of perchlorate in drinking and waste waters. Batch sorption tests will be conducted at perchlorate-concentration ranges commonly observed in municipal water supplies and process wastewaters. The selected and optimized SMC and SMZ will be pelletized and used in Phase II rapid small-scale column tests (RSSCT) to determine the most cost-effective sorbent. Potential commercial configurations for application of the technology include use in packed bed reactors as filtration media for removal of perchlorate and other groups of contaminants from drinking, agriculture irrigation, and fresh water. Additionally, the relatively low-cost SMC and SMZ may be used in combination with GAC in canister-type water filters in homes. Prefiltration with SMC or SMZ should extend the useful life and reduce replacement costs for GAC, resins, and ion exchange media. Tailored clays and zeolites also show great potential for removal of perchlorate from brines produced during regeneration of ion exchange resins, process wastewater from manufacture of some medical products, and munitions. In summary, our system provides a low-cost sustainable alternative to the traditional systems now in use. We believe our system will exhibit high-efficiency removal of perchlorate from drinking water and wastewater. While other perchlorate filtration techniques (e.g., ion exchange resins) produce a hazardous waste (i.e., perchlorate-contaminated brine) the spent nonregenerable (load and toss) tailored clays are rendered nonhazardous and may find use in other applications.