The U.S. Navy has significantly improved its operational capabilities in littoral and near-shore seawaters, which has resulted in the need to achieve much better pre-treatment of the seawater withdrawn from the often turbid and debris-filled shallow waters for the onboard desalination systems. Low-maintenance microfiltration is now used for pre-treatment, and it relies upon periodic electrolytic hypochlorite-enhanced seawater flushes. Increased littoral deployment of naval vessels has also seen an increase in biological fouling and clogging of vessel cooling systems, leading to the installation of electrolytic chlorination systems on ships and submarines to control biological fouling. Efficient electrolytic chlorination requires an active control feedback system in the form of a compact, near real-time in-stream detector capable of continuously detecting and reporting the total residual oxidant (TRO) content in the hypochlorite-enhanced seawater streams that the Navy uses for periodic biofouling control flushes. Efficient control/monitoring of electrolytic chlorine-generation systems requires a TRO sensor that will operate accurately, reliably and for long durations without maintenance in the marine environment. Pronghorn Technologies proposes to develop a proprietary halogen oxidant sensor technology with proven robust, long-term measurement stability to operate from 0 to 500 ppm TRO to provide near real-time control feedback in a seawater chlorination system.
Benefit: The proposed technology will be designed to meet the most stringent operational needs of the Navy. We expect to eliminate the current problems with todays state-of-the-art total residual oxidant detectors, including excessive dead time 0x9D between measurements, large size, logistical challenges, and problematic and labor-intensive maintenance/calibration requirements. We anticipate that the Pronghorn next-generation chlorine sensor will meet or exceed all Navy performance requirements and will be compact, rapid, reliable, and very simple to operate, with no need for expendables or consumables. Moreover, potential dual-use commercial applications for improved seawater desalination systems that make use of the proposed total residual oxidant sensor and sensing system include the increased use of land-based metropolitan water systems and extend to the automation of biological fouling control for industrial cooling towers, HVAC make-up air humidification, marine fire mains, vessel ballast water, fishing vessel holding tanks, seawater cooling systems, and pressurized seawater cleaning systems, in addition to the hypochlorite-enhanced seawater flush systems described in this proposal. With respect to the sanitation aspects of automated halogenation systems, commercial applications include potable water supplies in ships, recreational vehicles, pools and spas.
Keywords: water purification, water purification, microfiltration sensors, hypochlorous acid, Total residual oxidant sensor, electrolytic chlorination, biological fouling, Desalination, hypobromous acid
