In the News

DESALINATION PLANT IN SANTA CRUZ TO TURN SEAWATER INTO DRINKING WATER

By Graham
cournalist.com, 04/15/2009

On the furthest edge of Santa Cruz and the cutting edge of science itself sits a small, unassuming pilot plant that promises us greater abundance of the most basic ingredient of life. Water, the taken‐for‐granted liquid that we use to shower, wash our hands, flush our toilets and drink when we’re thirsty. Water, the one thing you truly can’t live without and the very cornerstone of the civilized, industrialized world. The project is the latest attempt to deal with a stark reality: Santa Cruz is running out of water.

It's no surprise that we’re running out of water. We have an expanding population, thanks in large part to UCSC, and a climate that is trending towards hotter and drier. Simple math shows that more people using less water leads us towards what could become massive water shortages if action isn’t taken. Luckily, the people of Santa Cruz and Soquel have enough foresight to act now against the water troubles of the future.

Currently, our water comes from a diversified portfolio that includes surface water, ground water, banked water and recycled water. The effort on behalf of the Santa Cruz Water Department and the Soquel Creek Water District (scwd2), to identify and utilize a new water source looked at over 30 solutions including constructing new reservoirs, importing water, recharging groundwater, and making increased use of recycled water. In the end, the search has landed in the most likely of places: the ocean. Water doesn’t grow on trees but it does grow in oceans, or so it would appear, and if sea water could be efficiently harnessed and purified we’d be looking at the holy grail of water sources.

A number of problems stand in the way of anyone turning sea water into drinking water. On top of the 35,000 parts per million of salt that need to be removed from the water, you have bacteria and viruses, pharmaceuticals, solids and metals in the water that need to be removed to a safe level. Then there is the issue of where you are getting the water from. You need an intake pipe big enough to meet your desired output, but it needs to operate such that it doesn’t damage the environment or the ecosystem. You need a large enough plot of land close enough to the ocean to build the plant. And you need something to do with all the brine ‐the concentrated salty waste solution that is produced as a bi‐product of purification.

The people of scwd2 have been dealing with all these issues effectively, scientifically and quickly. The eventual goal of scwd2 is to get a large‐scale desalination plant up and running that will be capable of producing 2.5 million gallons per day of drinking water. This is water that has not only been desalinated, but has been cleaned of other harmful constituents and perhaps even supplemented with a few minerals to mimic the water we’re accustomed to drinking. Because this is a joint effort on behalf of Santa Cruz and Soquel, the water produced will be divided between the two municipalities. During draught conditions, Santa Cruz will run the plant at full capacity, generating 2.5 million gallons per day for immediate use. All other times, the Soquel Creek Water District will use the plant to generate 1 million gallons per day to absorb into their water portfolio.

In March 2008, the scwd2 launched a pilot plant at the Long Marine Lab to investigate four different methods of desalinating and purifying sea water over the course of one year. Once the year‐long experiment had concluded, they will pick the most effective, reliable, and energy efficient purification process, and construct a new, large scale desalination plant. For the sake of comparison, the output of the current pilot facility is 72,000 gallons per day, whereas the projected output capacity of the full-scale plant is 2.5 million gallons per day.

We’re still years away from seeing the large scale desalination plant up and running. The pilot facility will run until March 2009. At that time, the processes will undergo a final evaluation and a best process will be selected for use in the future plant. An Environmental Impact Report on proposed locations for the plant and intake pipeline could take us through 2010. Finally, construction of the new plant is not projected to be complete until 2015.

The good news is that the tests are going quite well. All four of the pretreatment systems being investigated have been effective in removing solids and foulants, and have produced filtered water that has met or exceeded the goals for water quality. The reverse osmosis membrane technology being used in all processes meets all federal (EPA) and state (CDPH) drinking water standards. The people behind the project are working hard to be as energy efficient as possible, and to minimize any impact on the environment. So even though the full‐scale seawater desalination plant won’t be affecting our water supply until 2015, its good to know that when we start tapping it, it will be good clean water, it will be produced with energy efficiency in mind, and it will not be harming the environment.

Now if only the multinational conglomerate corporations of the world would take a page from the scwd2 playbook, and prioritize thorough scientific investigation, environmental impact and energy efficiency over profits and immediate output.

 

 

 

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