Why we should recycle instead of Desalinating!

So previously I discussed the links between energy and water in modern society, in particular the costs of desalination.

Today I just wanted to give a short comparison between recycling water (and yes recycling sewage) and desalination. Basically the only reason that Australia's major cities have desalination plants is because people are a little squeamish. Or to put it another way because people are stupid. If you tell someone that the resulting output is cleaner and less contaminated than regular water they still won't touch it, the problem is that it is psychologically dirty. People think that it is dirty and can't drink it.

The problem is people don't think further than that. The reality is that if you live in a country town (or Adelaide for that matter) then you'll probably be drinking 'recycled' water and not really think about it. The difference here is that somewhere further upstream some towns "output" has been cleaned etc and then squirted into the river, then the downstream town pumps this out of the river, processes it etc and pumps it around town as its water supply.

The difference with places like Sydney and the Gold Coast is that that process would be short circuit the "psychological cleansing" that shoving the water into a river and pumping it out again is removed. What people don't understand is that it makes no difference. What is equally silly if you think about it is that this is what is happening in Sydney anyway, they pump the shit out the "deep water outlet" and then suck in sea water for the desalination plant....

I'd love to think that if people knew a few things about it they would want to chose recycling water over desalination anyway. One it is a heap more efficient to recycle water than to desalinate it and two the recycled water is actually a lot cleaner.

To take the first point the efficiency of recycling lets consider Singapore, arguably the most advanced country in terms of both desalination and water recycling technology. Their most efficient desalination plant uses 3 MWh/ML where as their most efficient recycling plant uses 0.7MWh/ML to produce drinking water.

To the second point, again using Singapore as an example, several Silicon processing companies have relocated operations to Singapore because of the reduced costs that surround using the recycled water output. Silicon processing, specifically the production of wafers for semiconductors, requires very pure water. Singapore supplies this companies with output direct from their recycled water plants that is so clean they can vastly cut down on the amount of processing that they do on the water before it is used in their processes.

Finally, and this applies to both Sydney and South East Queensland the power requirements of desalination place such an additional burden on the power systems that we will not be able to meet it without considerable investment in power supply and generation infrastructure. When you factor in the increased water bill to subsidize the construction and then operating costs of the new water plant and the increased power costs for the infrastructure and new generation capacity there will be a serious impact of the desalinized water on the consumer.

Perhaps this hip pocket impact will make people rethink the "Desalination is King" mantra and reconsider both recycled water and storm water capture technologies.


SOURCE: IEEE Spectrum 6.10