by Mackenzie Anderson
Today, Los Angeles depends on water diverted from the San Joaquin Sacramento River Delta, the Colorado River, and the snowpack in the Eastern Sierras. These are the waters that enabled LA’s existence through feats of engineering. While conservation is always beneficial, LA ‘s move away from diversion requires people to take a step away from these ontological roots. Ideas about what water is good and what water is bad needs to be reframed.
SAVE THE DROP LA
California recently experienced a 7-year drought. The farmers felt it, scientists studied it, and politicians knew it too. Several initiatives were put in place to reduce urban water use. After all, mobilizing a dense population is a lot faster than solving legislative, agricultural, or infrastructural challenges impacting water distribution and use. In the future, it’s projected that LA’s population will continue to grow and that droughts will become more intense in California and across the world.
“Save the Drop” is one organization that helps citizens do the most with the water that they have, and to save money in doing so. Central to Save the Drop’s website are LADWP rebates for practicing water-saving habits, like using a rain barrel, or installing water saving appliances, like a faucet aerator. Angelinos also encountered signs like the one shown here on trains and buses across LA.
Other government initiatives in LA arose in response to the drought across all departments. For example, residents can apply for free trees for yards and LAUSD has been introducing new curricula and programs focused on water management and conservation. With the success of Save the Drop under its belt, the Mayor’s Office has, contained in LA’s “Green New Deal pLAn,” a lofty outlook for water use in LA. With the goal of 70% local water use by 2045, the expansive plan specifically talks about purifying water for groundwater recharge, using non potable water in local industry, and collecting storm water runoff.
While all of this is beneficial, sometimes the most straightforward ideas for really closing the loop on water use in cities are avoided. What about having a world where local water, zero diversion from “natural” systems, refers to a very specific set of water molecules kept and used over and over again.
A LESSER KNOWN DISCOVERY
When walking by the engineering school at the largest public University in California, the University of California, Los Angeles, tour guides like to brag about how “the birth of the internet” happened there in 1969. Most visitors can grasp the impact of that technology and how it changed how we live. Few know the tale of a slightly more eclectic discovery that happened a decade earlier in the same building, one that has and is changing the world in less visible ways.
In the late 1950’s, Sidney Loeb an immigrant from Israel and Srinivasa Sourirajan, an immigrant from India serendipitously gained access to a new source of potable water. The source: the ocean, a briny solution that compelled the Ancient Mariner to say “Water water everywhere, nor any drop to drink.” Taking the salt out of ocean water, was not a new idea, but in many cases, in was prohibitively expensive.
Let’s take a look at the options available before their discovery. One could force water through a symmetric membrane, which for them referred to a dense layer of synthetic material (like plastic), and eventually some water would pass through. This was impractical because of the energy required. The other option was to heat the water until it evaporated. One can then cool and condense the steam and collect the clean water. This too took a large amount of energy, and had its own set of infrastructure challenges.
The Loeb-Sourirajan membrane was the first that made the former process happen a lot faster and using much less force. By discovering that membrane asymmetry, arising from the process used to make a certain type of membrane, could reduce the energy required well below evaporating and condensing water, a new industry was born.
A membrane works by essentially slowing down one substance while letting the other pass through quickly. Think of rush hour traffic on a freeway. As the cars slowly navigate past each other, inching along, motorcycles are able to zip right through and reach their destination. With a membrane process the membrane material slows down the substances dissolved in water (the cars) much more than it slows down the water (the motorcycles). This interaction is based on the chemical makeup of the membrane where atoms of different sizes and charges slow some molecules down more than others. Some separations are more complicated than others and arranging the atoms and charges has to be tailored for the specific compound(s).
WHERE WE ARE NOW
Presently, most commercially available membranes are made from a material called polyamide, which is similar to the nylon used in clothing. Although designed for separating salt from water, it’s also the standard for aqueous separations including the purification of sugar cane and pharmaceuticals, the concentration of fruit juice, the processing of dairy products, and for cleaning up some Superfund sites.
In order to truly reap the rewards membrane technology offers, it needs to be everywhere. Membrane scientists and engineers in LA and across the word are working to make water re-use the rule, not the exception, as we move toward a more sustainable future.
BRING ON THE MEMBRANES…?
Most of the water that comes from a tap in LA has passed through a treatment plant in Sylmar after taking the long journey over the mountains from northern California. This is costly in and of itself. After being thoroughly cleaned, distributed, and discharged from a tap, it is then sent to Hyperion Water Reclamation Facility, where it’s purified again. Purified water from Hyperion Water Reclamation facility in Los Angeles is then discharged into the ocean. Only 2% of water is recycled in LA, mostly by industrial plants like the Exxon Mobil Refinery in Torrance. The refinery treats the water again and then uses it in their cooling towers. One might think the name ought to be Hyperion Water Discharge Facility.
What many would like to do instead is to further treat it send it back to the water grid. This is called “Direct Potable Reuse” or DPR. This begs the question, why isn’t this closed circuit system in the pLAn for LA? Indirect potable reuse or IPR, in contrast is collecting the clean water, pumping it into the ground, and then pumping it out again, which sometimes makes the water dirtier than when injected. Now, groundwater recharge, similar to IPR is in the pLAn, But, in addressing water recycling more specifically, it is clarified in the fine print as “*including but not limited to non potable reuse, groundwater recharge, and supporting environmental and recreational uses such as those in the L.A. River.” This is easy to overlook, but in the eyes of some, it is a loaded comment. There’s a hidden barrier there someone is not willing to break through.
WATER WATER EVERYWHERE
Plans to bring DPR or even IPR to LA county in the past have failed due to cost and consumer fear. Fear of what the water might be keeping. But as technology is getting better and information is at our fingertips to vet, it’s time to get ready for a vote. In the end we are the water keepers; we choose what to pay attention to regarding water. Truth be told, all water is good water, never permanently tainted, and now it is easier than ever to see and remove what might be hidden in it.
The Mayor’s fund for Los Angeles has already set aside 1.8 billion dollars for water projects with a goal to reach 30% imported water by the year 2035. Right now, we import 85% of our water. When discussions such as these make their way to the ballot again, think about the Ancient Mariner and how today several middle eastern and gulf countries rely on desalination for most of their potable water. When it is time to move beyond Saving the Drop, LA cannot afford to miss its window of opportunity.
Mackenzie is part of the 2018-2019 INFEWS program cohort and a PhD candidate in the Department of Chemistry and Biochemistry at UCLA. Her research focuses on developing new membranes for water purification.
This is a pop science article produced in the Science Communication course. The blog is part of the INFEWS Social Media Series.