What are the Environmental Implications of a Seawater Treatment Plant?

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.

In this article, we will look at three causes for concern in a sea water treatment plant and discuss the ways they can be avoided.

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• Reverse Osmosis
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• Desalination
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• Membrane Filtration
• Sea Water Desalinisation
• Equipment & Machinery
• Sustainable Desalination
• Desalination Pre-treatment
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6 Comments

1. 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.

2. 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.

3. 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.

    

   1 Comment reply

   1. John, reverse osmosis desalination can be used in both decentralized and centralized platforms based on the client (municipality or commercial/industrial user). Air to water systems has its place in certain smaller applications, however, the cost per production ratio is fairly high as well.

4. 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.

   1 Comment reply

   1. Guy, there is certainly regional water scarcity. This is apparent is coastal communities and island nations without a regenerative water supply.  Droughts, which are typically cyclical cause regional water scarcity as well. There is also water scarcity due to the effects of regional water contamination. Yes, adding chlorine to a centralized waste collection system prior to discharge alters surface water ecosystems and should not be done. UV is a better choice for these applications. 

5. 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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   1. Deni, even though desalination plants do have their place for potable water. Of course, too many desalination plants close together could potentially cause elevated regional salinity if properly engineered dispersant discharge systems are not utilized and the body of water is rather narrow. For example, the red sea has witnessed elevated salinity levels with large desalination plants operating in a relatively narrow body of water. However, ocean salinity tends to remain stable with relatively mild impact on the hydrological cycle. Remember, each of these water supply solutions are to be used in aggregate with other solutions as well. For instance, island nations or water scarce coastal areas could potentially use sea water desalination, in addition to potential air to water systems, wastewater reuse systems, rainwater collection systems to meet the water supply requirements that are needed.  

6. One of the biggest concerns around Desalination and RO is the release of super concentrated Brine. The technology offers many positives but the negative side cannot be ignored! Studies has been done in the ocean around harbor areas and found the concentrations of heavy metals toxins are much higher where desalination plants are installed. This will affect the ecology and water life systematically in these areas and ultimately end up in the fish we consume. RO has the same negatives and although the release of brine is highly regulated, the enforcement is the issue in many countries, especially developing countries. I have come across countless RO systems where the brine is merely released into ground water, today in countries like Pakistan, India etc the ground water is contaminated with heavy metals, toxins, phosphorus etc. With these systems becoming less costly and more popular, I am afraid the negative environmental impact is only increasing...

   1 Comment reply

   1. Dave,

      Of course there is pros and cons to desalination and RO. In fact, one of the previous articles that I wrote and that was published on Water Network dealt with this issue directly.

      Yes, the brine needs to be dealt with, and there will probably be in the not to distant future technology to handle brine stream treatment effectively.

      One item worth mentioning is RO pretreatment. Using pretreatment mechanisms to limit/reduce heavy metals, toxins, phosphorus before entering the RO system will allow significantly lower concentrations of these parameters in the brine streams that are discharged.

      I agree that other technologies need to be utilized in addition to RO to handle these parameters in third world/emerging countries with RO handling TDS reductions primarily.