What is the Environmental Considerations of a Sea Water Treatment Plant?
July 24, 2019 By // by Genesis Water Tech
A sea water treatment plant was designed as one of the solutions to the recent water scarcity problems. Fresh and drinkable water isn’t easy to find in some places. As the world’s population grows and industrial production increases, even the largest of the world’s freshwater sources can eventually become strained. Therefore, desalination is meant to expand our sources of water across the world.
As with any technology and/or process, there are implications that must be considered with regards to the environment. Many newer designs are promoted with the intentions of improving on an environmental issue encountered with past designs.
However, there are often negative side effects from these new designs on ecosystems as well. Some effects can be circumvented with considerate design, additional technology, and/or processes.
A sea water treatment plant is one of the world’s solutions to water scarcity. However, it also has its own possible environmental concerns. Of course, there are ways to reduce or negate those effects.
Below, we will look at three causes for concern in a sea water treatment plant and discuss the ways they can be avoided.
Intake
Before treatment of seawater can even begin, it has to actually be pumped in from the ocean or a beach well. The easiest way to draw in ocean water is directly.
As everyone knows, the ocean is filled with marine life of all sizes. Remember the scene in Finding Nemo when the aquarium fish are attempting to escape to the ocean? Nemo, the smallest, shimmies his way up the pipe into the filtration unit and nearly gets himself killed. Now imagine a much larger group of fish and even smaller creatures within the vicinity of a pump sucking in thousands or millions of gallons of water a day.
These sorts of intakes can displace and cause harm to local marine life via impingement or entrainment. Larger fish and organisms can become trapped on the intake screen while smaller organisms can get sucked into these intakes piping.
It is difficult to tell exactly what effects this has on the marine ecosystem at large, but unnecessary injury or death to marine life should be avoided at all costs.
To minimize damage to any marine organisms, one of the simplest solutions would be to remain cognizant of the location of the intake suction lines. Ideally, this would be in an area with a lower population density of marine life.
There are also design and technological measures such as low-velocity intakes, increased recovery, physical barriers, and behavioral deterrents. These measures can minimize ecological impact potentially caused by a sea water treatment plant.
Specialized gravity feed low intake velocity sea water intakes would allow fish and other marine life to escape the induced pump suction. This reduces strain on RO pretreatment systems.
In addition, increasing the recovery rate based on the seawater salinity source would decrease the required seawater intake volume. Physical barrier deterrents like air bubbles, or strobe lights could keep marine life from wanting to go near the intake.
Brine Outflow
When I was in high school, I took a marine science course. Our rather eccentric teacher decided to invest in a saltwater fish tank for the class. That particular teacher ended up retiring before the semester was over, but before he left, all the fish in that tank died.
Saltwater fish tanks are notoriously difficult to maintain because the salinity of the water cannot drop too far below or above 3.5%. Many marine organisms are extremely sensitive to such changes in their environment. The ocean happens to be self-regulating, but local salinity can be influenced with large amounts of concentrated brine water, especially in areas with slower moving currents.
After desalination, a brine concentrate is left over with a salinity twice as high as normal ocean water. The easiest way to dispose of it would be to simply return it to where it came from, the ocean.
But in many cases, simply dumping it all in one location could cause imbalances that can harm wildlife.
Care should be taken when discharging reject brine water back into the ocean. The main issue is with poor mixing areas with slow currents. To combat this, solutions such as specialized multi-port diffusers are utilized. These diffusers would be added to the discharge system, and are specifically designed and tested to dilute the concentrate over a wide range of ocean area.
Other options to handle this brine concentrate if available, could also be diluting with treated wastewater discharge from treatment plants or cooling water from power plants based on seawater treatment plant location.
For more information about some of the possible impacts and solutions for seawater desalination intakes and outflows, have a look at this report from the Pacific Institute from 2013.
Subsurface Pipes
Unfortunately, I don’t have an anecdote for this one. It’s pretty straightforward, really. When dealing with underground pipes there is always a chance that they will leak, and when subsurface pipes leak, whatever fluids they are carrying (and any subsequent contaminants) can penetrate through to groundwater sources. In the case of desalination plants, leaks could result in higher salinity groundwater.
Not only could groundwater be affected, but if the pipes happened to pass underneath any plant life, the salts could affect the soil composition, This could cause harm to vegetation by impeding their absorption of water.
Preventing such things from happening is pretty standard for any treatment systems that have underground pipes. Sea water treatment plant personnel should make sure to monitor for potential leaks and respond accordingly.
Looking for a seawater treatment plant, but are concerned about the environmental implications? Contact the seawater desalination experts at Genesis Water Technologies, Inc. at 1-877-267-3699 or reach out to us via email at customersupport@genesiswatertech.com for a free initial consultation to discuss your particular project details.
SOME COMMENTS
Arturo Constante 10 months ago
Nanoplastics into fish is one of the negative consequences of polymer (or monomer) membrane treatment, mainly RO; the other is high saturated salty brine, around 65,000 ppm while deadsea is around 45,000 mg/l, also high energy consumption is another considerable CO2 footprint.
any "solution" with negative environmental or sustainable disadvantages is just a palliative but never a solution, so my position is that RO is just a drinking water palliative while contaminating sea fish unhealthy for humans and planet.
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Garry de la Pomerai a year ago
Its necessary to reasonably blunt about the technologies of desal and its daughter tech RO. Both are indeed highly destructive to their discharge environments. RO is highly inefficient, discharging a residual very high brine of 40 to 60% of intake. The older larger RO facilities are even less efficient. And as RO is predominantly inland, their discharge is usually designed to be into wells deeper than their intakes and anywhere up to a Km from the intake. The critical problems for RO discharge are: 1. assuming the cheapest extraction is from the shallower unconfined aquifer , by discharging deeper below intake, you are discharging into the confined aquifers at a lower level; these deeper confined aquifers are often the best potable water resource , so 2. effectively you are dumping into others water supply, or 3. indeed you are contaminating the regions long term water supplies that are hydrating the earths crust with brine. Brine ascent through the soils to the surface via the evaporation process, thus long term you add to the devastating permanent contamination of productive agricultural land. RO has also a heavy carbon footprint due to its energy needs, its high consumables of filtration and chemical additives and the need for manpower attendance usually 24/7. That's the main damage of RO.
As for desal. People have correctly suggested their discharge is a problem even when regulated. Infact from experience most discharges regulations are not complied with, as it has to be dumped if the desal operation is to operate. Similar to pure RO, the residual discharge can be anywhere between 40 and 60% dependent upon the age of the system. This all goes into the shoreline. The damages include: a rise in local sea temperature by between 1/4 and 3/4 a degree along with potential tripling the saline ppm . The effect is bleaching of coastline corrals, with the knock on effect of killing off the shoreline eco system, ie fisheries, shell fish/ crustaceans, pearls, which long term effects offshore sea life and the reliant birds and onshore eco system. Interestingly the rise in the residual high mineral brine and rise in temp encourages the red algae, which blocks the desal intakes. Karma? Remember we are not discussing only today or the next 20 years but the 100 years long term sustainability of our eco systems and the present strategy damage of employing and creating a reliance upon more and more desal and RO facilities.
Ok so that's the knocking of the presently technology and the recommendation that in fact it ought be phased out! rather than expanded. But we should not suggest this IF we dont have alternatives. We do, and with no buts, we could almost eliminate RO now, by employing different strategies. Sorry , there is a but, but there is such a commercial industry built up around RO especially when we are losing our natural potable resources, that to suggest phasing them out would be political suicide. So how we are asked. Here a few headings. 1. Correct management of Diversification of water usage ie the right water for the right purpose. 2. Alternative water extraction from the atmosphere. The existing tech with a modified business model, minimizing its consumables simply needs to improve capacity. 3. Restructuring the present grossly mismanaged water resources 4. Education and redesign of home water usage 5. STOP polluting our existing water resources on surface and below ground eliminating the need for RO.
Did you know that outside of the extreme arid desert regions, where we should actually be living anyway, most communities and cities, villages once had their own private water resources in the forms of ponds, dykes, canals and leats, lakes, nearly ALL neglected, abandoned or abused, contaminated, therefore disused since centralised reservoirs were introduced with new infrastructure piping to abodes. That infrastructure from the reservoirs has also not been maintained. Consequently more and more wells and bore wells are dug, sucking the potable water aquifers dry. thus the present proliferation of RO and demand for desalination. a vicious circle of decline. The complexity of solution can be further discussed. The solutions exist.
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John Turner a year ago
Whilst we continue to be obsessed with centralization of all utilities supply for profiteering and control, there will never be enough. Decentralizing gives people choices. I can give you a system of air to water generators that can be owned and operated by co-operatives leaving very little impact compared with other systems, certainly any needing the RO routes. Contact me.
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Guy McGowen a year ago
Nick; it seems man will do anything to make a profit instead of allowing nature to clean itself. The solution to any problem is to stop doing what causes that problem. follow natures rules and problem solved. There is actually no scarcity of fresh water. Just persons adding chlorine to centralized waste collection system when nature has the proper microbes for this billion year old task. Taking sea salts out for fertilizers is ok. But hundreds of millions of gallons WILL mess up the hydrological cycle.
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Deni Gray a year ago
Additionally, although these desalination plants may help with potable water scarcity, how many is too many before a negative impact occurs in the hydrological cycle? How would this removal of sea water potentially impact climate change? I don't know the answers, but have a lot of questions.
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