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this post was submitted on 03 Oct 2023
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Salt is highly corrosive, especially when concentrated into a slurry. If you dump it directly from shore you kill any local wildlife and destroy the local area before it dilutes. If you pipe it further out into the ocean the pipe will continually need maintenance due to corrosion and makes it more expensive
Isn't that assuming you pipe it out using metal. Would plastic or carbon fibre be viable for this? Or at least coating a metal pipe?
There are a number of alloys that are used when working with desalinization plants, but the effective ones are cost prohibitive.
Even if they had a way of pumping it out cheaper, it still comes with issues that are costly. There are chemicals used during the process which pollute the brine and cost money to remove. It also comes out much warmer than surrounding water which disrupts the ecosystem. The brine eats up oxygen levels and suffocates animal life in the area.
They are trying to dilute the brine before releasing it back to the ocean but this is either not effective enough since you're using salt water from the same source you're pumping into, especially if the area doesn't have strong currents to carry it away. Or you're using water which doesn't have high salt levels and can dilute it to healthy levels, which you might as well just treat and use in the first place instead of using saltwater.
It's not an easy problem to solve at the moment
Fair points. I appreciate the response.
UK water companies are starting to explore this option and are hitting huge regulatory barriers as the by-product is considered industrial effluent. It will require regulatory shift. I'm wondering if anyone has done the maths properly though. How much salt do we mine each year? And how does it compare to the salt produced by desalination? If the average consumption of water in the UK is 125 l, then we can compare the salt produced to the salt consumed per capita every day in the country (e.g. industrial use, salt spreading on roads, etc.).
The truth is that you'll never be producing 125 l for 69M people all from desalination. Only a very small fraction of the 125 l will come from desalination.
The challenge is being driven by climate change and stringent environmental legislation in the UK water industry. These challenges are creating large gaps in their water resource planning for their future water supply. Hence desalination and effluent reuse now being considered as options. Its all in the water company water resource plans that have been published on their websites.
And BTW, I don't fully understand why 3 people have down voted this post. Its an incredibly interesting topic.