By Clifford L. Fasnacht, MWS
Desalination (also known as desalting or desal) is the process of removing salts and dissolved solids from saline water (brackish or seawater). In addition to minerals, the process removes most biological or organic chemical compounds. Modern desalination processes are based either on thermal distillation or membrane separation technologies.
Looking back at California’s legislative history during the late 1980s, desalination was viewed as a potential and viable water source during those drought years. With the official end of the drought in the 90s, however, the high cost of desalinated water fell out of grace. In 2002, the California Legislature approved Assembly Bill 2717 (Hertzberg, Chapter 957), which states: “This bill would require the Department of Water Resources to convene a Water Desalination Task Force to make recommendations related to potential opportunities for the use of seawater and brackish water desalination” by no later than July 1, 2004. The department was to report to the legislature the potential opportunities for and any barriers to the use of desalination technologies. The task force was to identify any potential roles the state should or could be involved in for furthering the use of this technology.
One of the many findings of the task force noted that economically and environmentally acceptable desalination should be considered as part of a balanced water portfolio to help meet California’s existing and future water supply and environmental needs. Future desalination could provide significant and numerous benefits, which include:
• Augmenting water supplies to help meet existing and potential demands
• With recurring droughts certain, providing water lost to these supplies
• Supporting water reliabilities
• Providing sustainable potable water
• Relieving some overdraft conditions
• Redirecting water for other uses
While many water districts, small towns and communities have expressed growing interests in this technology, several major hurdles stand in the way of implementation. Among the obvious is funding, whether federal, state or local. With the continued drought in the western states, increasing population and decreasing groundwater sources, the high costs of yesteryear are being revisited and appear to be more acceptable as water sources dry up. Technology has advanced significantly since the 90s, providing viable options for energy reclamation, more efficient membranes and greater pump efficiency, all working together to bring the costs of building, operating and maintaining desalination plants into an acceptable range.
Funding isn’t the only distraction for desalination plants. Environmental issues top many of the charts, with concerns over wildlife, fowl and other sensitive creatures the usual suspects. Other concerns include disposition of byproduct discharge streams and where to dispose of them. This generally revolves around the possibility of discharging the concentrate back into the ocean, from whence it came. Additionally, there are concerns about temperature change and increased salinity in the immediate area of discharge. Other issues with desalination plants are location, energy supply and impacts on the surrounding ecosystem. One particular community exploring the desal options is the Monterey Bay area. Among the many listed concerns is who will manage the plant, who will benefit and who will bear the burden of these issues. The struggle is not over and many more concerns will arise before a plant is actually built in the community.
Desalination is a proven viable technology in many parts of the world and is sometimes the only source of life-giving water. Will or would desalination solve California’s water woes? Not likely. Will it help? Studies show that if plants are designed correctly, where feasible, appropriate and economically prudent, desalination can be a viable, economically beneficial source of water for future generations.
What would a desal plant mean to a local community? There are currently more than 40 brackish groundwater-desalting facilities in California that generate approximately 170,000 acre-feet per year (counting both RO and ion exchange desalting). An additional 30 to 35 brackish groundwater desalting facilities that could generate nearly 290,000-acre-feet per year are possible in the next few years. Communities that suffer from contaminated water could use this technology to viably augment current supplies, reducing the strain on other water sources.
Desalination plants can provide jobs, help stimulate community growth and improve quality of life within under-privileged communities. As new processes and technologies are developed to increase energy recovery, balance between negative and positive aspects can be achieved and I believe will continue to favor the positive side. Discharge streams that have heretofore been dumped unceremoniously to waste are being explored as new sources of recovered/reusable water. Techniques are being developed that will allow better overall efficiency in our existing desalination plants and will be incorporated into new plants still in the engineering phase.
These are exciting times we live in today. The hope exists that one day in the not so distant future we will be able to supply clean, potable water to a vast population in our ever-growing world. The current processes will become a thing of the past as the great minds of the industry work and strive to further the technology of using seawater/brackish water to provide clean water for our needs.
About the author
Clifford L. Fasnacht, MWS, President of Pacific Purification Inc., has more than three decades of operational and management experience. As an entrepreneur (he successfully built Dougherty Pump & Drilling Inc. and Pacific Purification Inc.), he has a keen sense of adaptability in the service and construction communities. Fasnacht serves on several executive boards across the nation, including PWQA President and VP of the Central Coast Builders Association. He also serves on several task forces and education committees for the Water Quality Association (WQA) and is a charter member of the California Ground Water Association (CGA) and several trade-related organizations. Fasnacht has been honored with numerous certifications and awards for his work in the water treatment industry.
About the company
Pacific Purification Inc. is a service and custom manufacturing business that designs and builds products for many applications worldwide. Clients range from mega-corporation giants that include fertilizer manufacturers, pharmaceutical manufactures and water treatment companies, to private homeowners.