Portable Seawater Pulse Flow RO System with Feed Flow Reversal
Abstract
Clean, safe, potable water is a universal need for military personnel work but faces additional barriers for mobile and military needs. The dominant technology for purifying water is reverse osmosis (RO), as it can reject all contaminants down to the smallest salts and particles. However, small-scale RO systems (<100 L/hr.) have poor water recovery, often wasting ~70%, and have membrane fouling issues that increase maintenance. Centralized water systems typically involve transporting vast volumes of bottled water providedby RO, which entails enormous logistical complexities encompassing added security risks, vulnerabilities, and potential disruptions. To address these challenges, small-scale RO desalination systems that decentralize drinking water production have been developed for has low a population as 45 people. An extension of downscaling efforts to even smaller groups of about ten persons has been challenging due to the need for regular maintenance and inefficiencies introducedby fouling in membranes associated with conventional RO systems. We propose a novel system that uniquely combines two pioneering technologies: the first-ever passive pulse flow reverse osmosis (RO) system and the first-ever flow reversal desalination system with pulse flow. The proposed system incorporates the batch reverse osmosis (BRO) configuration, the most efficient method for moderate salinity desalination in a pulse flow reverse osmosis system with feed flow reversal (PFRO-FFR). The aim is to design and build a lightweight and portable, small-scale RO desalination systemthat not only accomplishes water desalination with low maintenance and few failure modes but also significantly reduces dependence on antiscalants. The proposed system is designed to maximize the amount of potable water (diluate) filtered, achieve higher recovery, enhance system efficiency, and enable fouling resistance using the PFRO system in feed flow reversal mode. We propose a system that prioritizes efficiency and reliability and develops specialized membranes with high salt rejection and fouling resistance, boosting the system s overall performance efficiency.The methodology for the proposed mechanical passive PFRO-FFR system temporarily blocksthe membrane module s concentrate outlet port, elevating the feed solution s internal pressure. This pressure increase drives additional water through the membrane, enhancing permeate production. The result is a higher water recovery rate and the induction of biocidal salinity cycling. Raw feed enters the RO membrane module through a 4-way, 2-position directional control valve during the normal forward flow. The permeate travels to the permeate tank while the brine is momentarily restricted for a pulse flow reverse osmosis (PFRO) operation using the pilot-operated valve. The brine is released for approximately 2 seconds, and then the flow is reversed with the same 4-way, 2-position valve. The same flow operation occurs in the feed flow reversalmode with a feed entry and exit switch. The project goals include a production rate of five gallons of filtered water per hour. The system is designed to be easily deployed (2ft x 2 ft x 1 ft), with a low weight (20 lbs.) and a low power consumption (battery powered, less than 1kW/Hr.). This emphasisis on practicality and ease of deployment. Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Nov 09, 2024
- Source ID
- N000142412780
Entities
People
- David Warsinger
Organizations
- Office of Naval Research
- Purdue University
- United States Navy