Advantages and disadvantages of desalination plants
Before explaining advantages and disadvantages of desalination plants. We try to understand history of brackish water and seawater desalination reverse osmosis technology.
History of Brackish Water and Seawater Desalination System with Reverse Osmosis
Brackish water desalination was the first successful application of Reverse Osmosis with the first large-scale plant built in the late 1960s using cellulose acetate membranes. The first seawater reverse osmosis (SWRO) was built in 1973 with the advent of high permeability polyamide membranes. By 1993, the SWRO total capacity had reached 56,800 m3/day. In 2008, membrane desalination constituted 50% of total desalination capacity of which 45% was RO and 5% was EDR. And the rest 50% was thermal. However, 80% of all desalination plants were membrane – 90% RO and 10% EDR (electrodialysis reversal).
Desalination dominates the RO market and breaks down to 51% desalination, 35% industrial and 14% residential/commercial and non-desal water. In 2012, the global desalination capacity exceeded 60 M m3/day with more than 60% produced by RO membranes. The global water production by desalination in 2016 is projected to be 100 M m3/day, twice the rate of global water production by desalination in 2008.
What is reverse osmosis desalination of seawater and brackish water?
With high pressure pumps, water is pressurized to pass through a finely pored semi-permeable membrane. Then filter the water. Around 99% of contaminants including salts, bacteria, and other particles are leaving the water in its most purified form. The system releases the purified (permeate) water from one stream. And also the reject fill with concentrated contaminants from another. Depending on the application of the water, post-treatment may be necessary.
The advantage of desalination plants
- Seawater reverse osmosis systems remove dissolved salts and other minerals from seawater and turn it to drinking water. It provides a solution for areas that have limited resources of fresh water and a reliable alternative source of water in times of severe drought.
- Desalination also produces water that you can use for irrigation. So it is great for arid regions or in many areas around the world where there is no enough fresh water.
- Positive improvements in the performance of RO membranes have greatly enhanced the use of seawater desalination. Since it becomes an alternative for fresh and potable water production.
- Seawater desalination systems have been in use over 10 years now, and its method is effective in creating fresh sources of drinking high quality water that is safe and reliable.
- As the freshwater supply on our world has limit, we should preserve its resources by utilizing the method of desalination to eliminate water shortage crisis that the world might face.
- We have plenty amount of seawater to produce freshwater through desalination, so even in times of droughts, there will be sufficient access to fresh water supply.
- Unlike other solutions that heavily rely on uncontrollable factors like rain or snowfall, seawater desalination systems do not rely on anything other than the ocean or seawater.
- Desalination plants usually locate away from residential areas and some of them are located in industrial areas, so they don’t put residential areas at risk.
- Desalination plants can reduce the pressure on freshwater sources. Seeing the ocean as a water supply, might help with increase the awareness in protecting our oceans.
The disadvantage of desalination plants
- Reverse osmosis Desalination plants consume more electrical power compare to normal reverse osmosis system.
- Desalination plants investment cost because of high pressure pumps and special membranes mpre expensive than standard reverse osmosis system.
- Desalination plant produces higher TDS concentrate water compare to standard reverse osmosis systems.
Conclusion
Desalination plants can be highly beneficial for arid areas or places that are experiencing intense drought. Investment cost and power consumption looks like high but if we compare it with evaporator or crystallization systems, it is economical.