In-tank recirculating arsenic treatment system
| DWPI Title: Water treatment system for reducing contaminant e.g. mercury in water, comprises water storage tank, recirculation pump, treatment column having contaminant-sorbing media, and piping, where water continuously recirculates through the column |
| Abstract: A low-cost, water treatment system and method for reducing arsenic contamination in small community water storage tanks. Arsenic is removed by using a submersible pump, sitting at the bottom of the tank, which continuously recirculates (at a low flow rate) arsenic-contaminated water through an attached and enclosed filter bed containing arsenic-sorbing media. The pump and treatment column can be either placed inside the tank (In-Tank) by manually-lowering through an access hole, or attached to the outside of the tank (Out-of-Tank), for easy replacement of the sorption media. |
| Use: As water treatment system for reducing the level of a contaminant (arsenic), chromate, perchlorate, heavy metals, trichloroethylene (TCE), perchloroethylene (PCE), selenium, vanadium, phosphate (PO 4 ), and radionuclides claimed). |
| Advantage: The water treatment system reduces the arsenic concentration below 10 ppb MCL (maximum contaminant level) requirement therefore enhancing the media utilization, which extends media life. The arsenic removal capacity of the arsenic-sorbing media is 1-3 mg As/g media. The recirculation flow rate through the treatment column is sufficiently high so that at least one tank volume turns over every 1.5-2 days. The water treatment system reduces capital costs by continuously removing arsenic, while the water is inside a community water storage tank. The water in the tank is continuously recirculated, at a significantly greater velocity than conventional adsorption, through a treatment (filter) column filled with arsenic adsorbing media. The in-tank arsenic removal system could be built and run at minimal cost and useful for small systems. The major cost savings relative to existing approaches occurs because no operators or new constructions would be needed. The system design is unique from other, traditional contaminant removal approaches because it uses the water storage tank as the reaction vessel; and provides the opportunity for multiple passes of tank water through the sorption media by continuous recirculation. The system maintains output arsenic levels by optimizing the flow rate through the media column. The in-tank system treats water in a single pass, and has size that can be much smaller due to continuous treatment. |
| Novelty: A water treatment system comprises a water storage tank (10); a recirculation pump (12); a treatment column, containing contaminant-sorbing media; piping (14) for recirculating water from the storage tank to the pump, then through the column, and then back to the storage tank. The water continuously recirculates through the treatment column, thus reducing level of contamination in water after multiple passes through the column, and before any treated water is distributed from the storage tank to users. The treatment system is not a once-through treatment system. |
| Filed: 5/1/2008 |
| Application Number: US2008113354A |
| Tech ID: SD 10055.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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