Brackish Water Remediation for Mekong River Delta

Our innovation is focused on solving two urgent problems threatening the future of the Mekong River Delta (MRD), one of the five biggest river deltas in the world: 1) Drinking water for the majority of the population, and 2) Loss of food production because of rising sea level and land subsidence thanks to the climate change.  A system of Low-Fouling NF Membrane is proposed with zero waste liquid discharge using induced ambient air drying. The system had been tested in the US market.
 

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About This Innovation

Innovation Stats

Funding Goal ($): 
What phase of development is your innovation currently in?: 
Potential Lives Impacted: 
6,000,000
Cost Per Unit ($): 

Provide a status update for your Innovation.

The Dean and the Vice-Dean of the Agri-Aquaculture Department of Tra Vinh University have decided to join the project to launch the initial prototype in the Mekong River Delta (MRD).  Tra Vinh Province is located on the coastal area of the MRD, which is subject to the worst impact of the climate change.  The LF-Nano Filter Module made by EconoPure in the US  is selected to be the engine for the Brackish Water Remediation (BWR) system.  A large-scale LFNano module capable of producing up to 50 cubic meter per day of potable water is being consisdered as the prototype for the MRD.

 

How does your innovation work?

The surface water from the rivers and canals in MRD is the most abundant sources of water.  The surface water in the coastal provinces is deemed unusable since it is contaminated by the tidal seawater, alumina, and polluted contaminants (VN Ministry of Natural Resources).  Currently, no viable technologies are being practised to convert surface brackish water to clean water.  We propose a patented Brackish Water Remediation (BWR) membrane filtration process with Zero Liquid Discharge to convert surface brackish water to clean water for the MRD inhabitants. The game changing innovation of this process is the ultimate protection of the membrane from fouling through: 1) Using of a sacrificial dynamic layer of Diatomaceous Earth (DE) to adsorp fouling impurities, and 2) Automated self-cleaning process is activated periodically to remove the soiled DE layer once it is filled with impurities then replace it with a new one.  The membrane is thus protected from direct contact with these impurities. BWR is designed to operate for years without the complexity of pretreatments and  membrane chemical cleanings.  These attributes make BWR very economical and friendly to users in the rural areas. A Nanomembrane is selected to remove enough salt, and most bio-contaminants, arsenics, aluminates, carbonates  to make product water compatible with the national standards. The waste brine can be evaporated using ambient air in a high-efficiency evaporator with a footprint only 1%-2% of an equivalent evaporation pond.  If electricity is unavailable, BWR can be operated using wind or solar energy.  The 10-year lifecycle cost of producing water from surface MRD brackish water is estimated within $0.3-$0.5/m3, significantly lower than seawater desalination ($1-$3/m3)(Water Reuse Committee White Paper, 2012).

Citations:

  • Erban L. E. , et al, Release of Arsenic to Deep Ground Water in the Mekong Delta, Vietnam, linked to Pumping-Induced Land Subsidence, Procedding of the National Academy of Science of the USA, August 5, 2013.
  • IUCN report: Ministry for Foreign Affairs of Findland, International Union for Conservation of Nature, Ground Water in the Mekong Delta, June 14, 2011.
  • Le, Anh T.  An Overview of the Drinking Water Siupply Situation  in the Mekong River Delta, Can Tho University, VN, March 2003.
  • Mackay, P. et al, SKM Consultants, Asian Development Bank, Climate Risks in the Mekong Delta, Ca Mau and Kien Giang Provinces of Vietnam,  ISBN 978-92-9254-206-1, 2013.
  • Padilla K., International Center for Environment Management,  The Impact of Climate Change on the Mekong Delta, ICE Case No. 265, Dec 2011.
  • Viet Nam Ministry of Natural Resources and Environment, Mekong Delta Plan, Long-Term Vision & Strategies for a Safe, Prosperous, and Sustainable  Delta, December 2013.
  • Water Reuse Association White Paper,  Seawater Desalination Costs, January 2012.

What Evidence do you have that your Innovation works?

Please review attached Excel File: Evidences Support the Innovation (306)

This Excel File summarizes data collected during the development of the LF-Nano, the filtration module utilzed in ther Brackish Water Remediation System (BWR).
The data are presented in the Excel page--(Chart-Sec)-- a chart summarizing 3 main tests: 1) OCWD Spiral Test in Blue, 2) OCWD Test #2 in Red , and OCWD Test #4RI in Green.  All the tests were conducted over several months thanks to the courtesy of the Orange Country Water District  facility in Irvine, California in 2008-2009.  All the tested membranes produce potable watert from the secondary treated effluent (STE).  STE from an OCWD facility should contains about 1200/1300 mg/l Total Dissolved Solids, of which about 800mg/l are Sodium Chloride Salts.  This chemical makeup is very close to the amount of salt in the Mekong River Delta surface brackish water.  The LF-Nano can remove about 50% of sodium salts and almost all minerals, metals, arsenic, virus, bacteria, and other organic contamminants.  The sterilized product water at about 400 mg/l salt is compatible with the international standards for potable water.

The LF-Nano module is constructed similar to a spiral wound membrane module, with membrane sheet wound into a roll.  The LF-module is designed by EconoPure so that the gap between the membrane layers is enlarged to accomodate a layer of Diatomaceous Earth (DE), a porous inert substance that has extremely high surface area per volume.  The DE layer covers the membrane surface to protect it from direct contact with fouling contaminants and debris in the concentrate brine.  Thanks to the large surface area, it can adsorp a large amount fouling chemicals.  Once it is fully soiled, it is scrubbed away from the membrane by the high velocity of the crossflow which is designed to be as high as 2ft/second.  The loss DE is repelenished fresh DE added through the feed. The DE layer is acting as dynamic and sacrificial layer to isolate the membrane from the high concentration of the fouling chemicals in the brine.

The removal of the soiled DE is strongly assisted by a patented process, the Periodic Self Cleaning Cycle (PSCC) developed by Dr. Dong Nguyen.  During this automated cycle,  pressure on both sides of the membrane are nearly equalized, allowing the soiled DE to be loosened from the surface to be conveyed away by the high cross flow velocity of the brine (2 ft/sec). Depending on the quality of the feed, the PSCC can last from several minutes on every few hours, or several hours on a few days. The PSCC is a powerful tool to eliminate or minimize the membrane chemical cleaning because of membrane fouling-- the major obstacle to the application of membrane technology in the developing world.  

The data collected at OCWD indicated that the most common commercial spiral wound seawater RO (SWRO) membrane reaches complete fouling point in about 7 days (blue line in the chart or OCWD Spiral Test).  When DE is added to the membrane (Red line or test #2), the life of the membrane can be extended to a month or two before cleaning is required since there is a slighly decline in flux rate.  The flux did not diminish with time or even slightly increased at the beginning when the PSCC is added to the operation every day (Test #4RI or green line).  The results were duplicated many time in subsequence tests on the field with other feed water types.

Do you have current users or testers?

The most popular size of the systems using the LF-Nano can produce 4 m3/day of potable water.  They are purchased by the following companies in various countries:

  • Pearl Blue Water co. for fracking water recycle, Bridgeport, West Virginia, US.  
  • Rexroad McKee Co., a Hydroponic grower in Reno, Nevada, US
  • Drinking Water plus additional hotel utility application in San Nicolas Hotel and Casino, Ensenada, Mexico. 
  • Makevale Polymer plant, Vadadora, Gujurat, India

What is your strategy for expanding use of your innovation?

The application of using the LF-Nano membrane in a Brackish Water Remediation system (BWR) is expected to be part of the infrastructture development for a country.  We choose the Mekong River Delta (MRD) to simplify our initial logistics since we currently have a network.  We believe that once the application is proven in Vietnam, it can be applied in many developing countries.

We need to demonstrate that the BWR is the optimal solution for the test country.  The system should require a minimum interference from users, produce consistence water quality and production rate, and economical.  The MRD is crisscrossed by a network of canals and river while only a skeleton of road structure is available.  Centralized water works can reach about 60% of the population.  The optimum water supplied to the remaining inhabitants, especially in the coastal areas,  is through decentralized water plant.  Clusters of 10-20 houses in a hamlet can share a water plant which takes the feed water from the local canals.  We plan to showcase our BWR with 40-50 cubic meter product water for this market.  

The market of drinking water for the coastal provinces are particularly suitable for the BWR.  The groundwater is contaminated with arsenic and salt.  The surface water is ladden with commercial and biological pollutants.  Both cannot be processed easily by the current technologies used by the public water work.  It is estimated that about 40% of the public water is not up to potable water standards.  The BWR can purify either undergroundwater or surface water to reduce Na salt, arsenic, aluminate and sulfate salt, and sterilize water.  The BWR can be economical at the size of 50 m3/d plant.  The BWR can be a good fit for the MRD inhabitants since it can bring clean water to the user without the costs of an elaborate distribution system.  It is estimated that about 6 million plus of MRD inhabitant can be beneficial of the BWR.

The BWR also includes an ambient air dryer which can replace the function of an evaporation pond at 1% of the footprint area.  This evaporate rate was confirmed in a demonstration at Alamogordo, New Mexico in April 10 2015 during the Desal Prize Contest orgainzed by US AID.  A description of the dryer is included in the "Description of the Innovation (308)".   The test at Alamogordo also show that if the elecrical grid is not available, the BWR can be operated using either solar or wind energy or both.

To pilot the BRW, the dryer, and the solar/wind energy option, it would take roughly 4 months at a demontration site.  First, a membrane needs to be optimized for the feed water, then a full-scale pilot plant can be built.  A detail cost analysis can be completed specifically for the location to prove that the technology is optimzed for the feedwater.

The BRW can be built mostly by the local shops using local supplies, except the filter elements.  They can be imported from the US or ordered from a country which has membrane module processing capability.  The cost of a BWR can go significantly below $20,000/unit if the System construction can be outsourced to VN.

Next Steps

The critical pathway is to demonstrate the technology and prove to the local inhabitants that the BWR technology is economical and optimzed for the MRD.  The demonstration entails the costs of construction of a LF-Nano from EconoPure, solar panels/ wind generator, a dryer, and to operate the system for at least 4-5 months. Once the demonstration is accomplished, the remaining tasks are less challeging since the supply of clean water to the MRD has been elevated to the national priority level by the Vietnamese government.  Commercialization of the BWR would be secured since it has becomes part of the nattional infrastructure development. The government would step in to provide low interest loans for the remote communities to acquires BWR water plant.  The role of Tra Vinh University would be pivoting since it has been an organization to disseminate  information for new technologies in the rural areas.  

Securing the grant or investment for the demonstration step is now the most critical step for this project.

 

Related Resources

  • In this powerpoint presentation, a general description of the Brackish Water Remediation Sytem, including the dryer is provided.  An outline of the ten year Life Cycle Cost for a system capable of providing 20 cubic meter of potable water is analyzed.  In cluding evaporation of the brine, the cost of water would not exceed $1.00/cubic meter.  This cost is considered to be very economical industry-wide.

    The cost is much lower if evaporation of the brine is not considered.

  • application/vnd.openxmlformats-officedocument.spreadsheetml.sheet LCCEXchange.xlsx (38.17 KB)

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