Grantee Research Project Results
Small-Scale Solar Desalination for Drinking Water
EPA Grant Number: SU840155Title: Small-Scale Solar Desalination for Drinking Water
Investigators: Venkatadriagaram, Sundararajan
Current Investigators: Venkatadriagaram, Sundararajan , Deuling, Ryan , Salameh, Yazan , Leon, Jose de , Gonzalez-Almacen, Aileen
Institution: University of California - Riverside
EPA Project Officer: Page, Angela
Phase: I
Project Period: December 1, 2020 through November 30, 2021 (Extended to November 30, 2022)
Project Amount: $24,995
RFA: P3 Awards: A National Student Design Competition Focusing on People, Prosperity and the Planet (2020) RFA Text | Recipients Lists
Research Category: P3 Challenge Area - Safe and Sustainable Water Resources , P3 Awards
Description:
In this project, we combine solar energy with flash distillation and latent heat
recovery. Solar energy provides electrical energy to operate an air blower and water pumps, and
to heat water. Air is forced by a blower through a Venturi section where air pressure drops. With
appropriate dimensional design of the intake and the Venturi throat, the pressure in the throat can
be reduced below the vapor pressure of the water. The water flashes into its vapor phase due to
reduced pressure and is blown by the air into a condenser where it condenses into freshwater on
the outside of tubes that carry the feed water. Feed water is heated inside the tubes, and is further
heated in a solar water heater. The hot water gives up some of its heat to increase the temperature
of the incoming air. Since the heated air can hold a greater amount of moisture, this leads to
increased throughput.
This project proposes the following innovations: the use of an alternate method to create
low pressures to effect rapid vaporization of water, the use of solar energy as the sole motive
power for the entire system, a design that can be readily scaled from the current target market of
single-family homes, the use of high water and air temperature to prevent the growth of biofilms
and negate the need for biocides. Lastly, due to the use of flash distillation, it is able to remove a
majority of contaminants without selectivity.
Objective:
The goal of this project is to develop a stand-alone water treatment system that can
provide potable water for indoor use in single family homes. The system will utilize solar energy
entirely and will not require the use of reverse osmosis. It will employ the principle of flash
distillation, but use fluid flow to produce low pressure rather than vacuum pumps or steam
injection common in flash distillation systems. The system will work with brackish groundwater,
seawater, or reusable water that has undergone simple filtration. This system is intended for use
in isolated communities in arid places such as southwestern areas of the United States where
clean water is in short supply but saltwater or brackish water may be more available and where
water reuse may be necessary.
Expected Results:
The project will create a desalination system that can convert brackish groundwater,
seawater or filtered used water into potable water. The system is estimated to deliver 1100
liters/day, and will rely entirely on solar energy. The water will meet drinking water quality
standards. The project aims to alleviate water scarcity and enable water reuse in arid areas of the
United States. It will make the beneficiary communities self-sufficient for water and will reduce
the strain on public water infrastructure systems that may be difficult to construct or maintain.
This system will reduce the need for expensive, environmentally damaging and energy intensive
water delivery systems such as canals and pipelines. It is assumed that suspended solids in the
feed water have been filtered through sand or other simple filtration methods, but that there may
still remain salts and other dissolved contaminants that require removal. Although initial
filtration is not considered in the scope of this project many inexpensive, well-established
methods of pre-filtration may be used to accomplish such filtration before introducing the water
into the proposed system.
Achievement of objectives will be measured by testing the throughput and quality of the
water produced by the system. During the initial phases of optimization, we will use laboratory
equipment to determine contaminant levels. We will use commercially available sensors and kits
to monitor pH, salinity, and chemical contaminants such as nitrates, arsenic and phosphates. We
will also collaborate with the R’Water community, a collaborative initiative at UC Riverside that
focuses on water issues, to obtain guidance on water testing. When the system has been
optimized we will use EPA certified water quality testing stations to ensure water quality.
As this system utilizes thermal distillation, it will not create byproducts typically seen with
chemical treatment methods. This also eliminates the need to manufacture, maintain and dispose
of membrane filters. Additionally, the sole use of solar energy power, and placement of systems
close to the output destination will lower pollution associated with operation and transportation,
compared to current technologies.
Supplemental Keywords:
Water Treatment, Desalination, Brackish, Reuse, Sustainable, Household, TransportAlternatives, Groundwater, Solar, Flash, Distillation, Greywater, Desert communities, Seawater
Progress and Final Reports:
The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.