One of the hard truths revealed by California’s five-year drought is that many small, rural communities lack the resources to adapt to water shortages. In this case, that means both money and expertise.
It can be very expensive, for instance, to build a new water treatment plant or connect with one in the next closest town. Even if a community finds the money to build a small treatment plant, it may not have anyone locally with the expertise to operate it.
These problems are not unique to California, but common to rural areas worldwide.
Now a team of engineers and students at the University of California, Los Angeles, has developed a water treatment system that fits in a 40ft shipping container. It can turn agricultural runoff, brackish groundwater and nearly any other water source into drinking water.
Mechanical efficiencies make it cheaper and more compact than existing technology. Real-time monitoring allows the system to adapt to changing water conditions, and wireless communications mean an engineer can monitor the system remotely using a smartphone or tablet.
The system is operating successfully at the Panoche Water District in California’s San Joaquin Valley, transforming up to 60,000 gallons per day of agricultural runoff into clean drinking water. The next step is networking a few small systems to serve several small communities in the Salinas Valley. Eventually these could be linked into a “virtual water district” that is overseen remotely by a single engineer.
To learn more about this new frontier, Water Deeply recently talked to Yoram Cohen, a UCLA engineering professor and director of the school’s Water Technology Research Center.
Water Deeply: Why did you embark on this project?
Yoram Cohen: We came to realize one of the things that is being neglected is the treatment of different water sources – and, in some cases, desalination – in areas that are not part of an integrated water infrastructure. The thought at the time was that centralized systems, like in major cities, are less of an issue. You’ve got large plants. In those plants you have folks who can be present 24/7 and run the plant, and they can handle upsets that occur and ensure the plant runs properly.
Now translate that to smaller communities that are scattered not just throughout California but throughout the U.S. and in fact the world. They are in a different position. As we were talking to folks from industry, we realized one of the key issues with such systems is how to improve the operation so that you will not need an operator 24/7. In many cases, where there are variations in water quality and water demand, such systems have to be able to respond autonomously and adjust their operating conditions – whether it means changing flows, changing chemical additives, the rate at which they are fed, and changing the pressure accordingly.
All of that would have to be done in a smart way, which means the system has to understand what is the impact of any changes in environmental conditions outside of the system and how to respond appropriately.
Water Deeply: You also looked at networking small treatment systems, right?
Cohen: Yes. The other element was, while this is OK for one system, imagine you have many systems that are distributed around. Then the question is, how will you be able to manage multiple systems and be able to have some sort of centralized but remote supervision? How do you learn from each system so that knowledge gained from one system can be used to improve the operation of another?
Since we have the small systems and they are distributed, how do we determine if something goes wrong with particular hardware, if there’s a problem with a monitor or with pressure, flow rate or salinity? So we started to get into the idea of fault detection and isolation. How do we know if the membranes are operating correctly?
So we developed technology for membrane monitoring as well. What that means is being able to assess in realtime what’s happening on a membrane surface. We’re using membrane technology for both water purification and water desalination. So if you have clogging of the membrane surface by particulate matter or bacteria, then that is detrimental to the operation. So we developed a specialized optical membrane monitoring. That really allowed us to utilize this smart monitoring, and on the fly develop various controls that allow us to respond in real time.
Water Deeply: Tell me about your first application in the San Joaquin Valley.
Cohen: We are operating at the Panoche Water District. The issue in that water is very high salinity. It’s groundwater and it’s also agricultural drainage water, a lot of which, if it could be reused, would make a huge difference. It also has organics. It has biological materials. So it’s not water you would reuse in many cases. Some of the really poor-quality water is not even water you would reuse for agriculture.
We have been in operation there, I think, for almost four years. This particular one is a high-end plant but it’s more than probably you would need for just commercial deployment. We have a technology being deployed specifically to harvest salts, to avoid any discharge that is typically created. We’re in a location there that is very advantageous because we have multiple water sources in one location. We have agricultural water and we also have water that is from the state project canal, and water that is a drainage water. Salinity where we are ranges from 1,000mg/l to almost 20,000mg/l. That’s compared to seawater, which is about 35,000mg/l.
The idea for the water we are treating is to be used either for agriculture or it’s of a quality that can be used for drinking as well.
Water Deeply: And what’s your next project?
Cohen: We have an effort to transfer that technology to much smaller systems to serve remote and disadvantaged communities in the Salinas Valley whose water supplies are contaminated with nitrates. They also have high salinity in quite a few cases, but they also have nitrates so they can’t drink this water. Some of them are getting subsidies in the form of replacement bottled water. Some are even afraid to bathe their babies with the local well water because it is high in nitrates.
They’re small communities. They don’t have either the expertise or the level of funding or income to be able to hire somebody who’s going to be able to run the system continuously. On the other hand, if we think about economies of scale, imagine you have 10 of those systems – 100 of those – and then the expert doesn’t have to be on site. The expert can be offsite and every system gets the same level of expertise because it operates in an intelligent way. All the systems, with today’s technology of wireless communication, they are also under the supervision of a remote expert. That’s what we’re driving for now.
Water Deeply: How expensive are these systems to set up?
Cohen: If you would use it to provide water for residential, you would probably be looking at $40 to $50 per household per month. It’s not a lot. It’s really cheap relative to bottled water.
The savings are mostly in terms of capital costs. We would probably save about 30 percent or even 40 percent of capital costs. It’s quite significant. Instead of using, let’s say, 10 membrane modules, if I use only one, that’s already reduced the cost of membranes considerably. It also reduces the cost of valves, connectors, the framing. And if your pump is a low-pressure pump, it also can be smaller, it also costs less.
To me, the flexibility is really the key. Which basically means with one system you can go and utilize it for seawater as well as brackish groundwater, and you don’t have to redesign the system. Because you can have a small footprint you can even put it in a smaller container or have a completely mobile system.
Water Deeply: What’s the growth potential for water systems like this? Where do you see it going?
Cohen: I really see it as going toward virtual water districts. This is really what we are pushing for. We first had to demonstrate that the technology is doable. Now we’re moving towards having three or four systems that are part of a virtual district probably within a year in the Salinas Valley.
Our goal has been to basically put ourselves to work and prove that we can form a virtual district that is enabled by advanced, self-adaptive technology and remote monitoring. The system will tell you if there’s anything wrong. In other words, the remote supervisor is a computer. At the end of the day, it will have to report to a human being, because a computer cannot go to the site and replace a valve or repair a pump. But it can do everything else all the way to decision support, and inform not just one person but whoever you want.
We’ve also been pushing toward technology, so all stakeholders can have access to information. The ratepayers would be able to watch what the treatment plant is doing, how much water is being used at what times, what kind of maintenance is being done, and so forth.
There are institutional concerns or hurdles to overcome, because anytime you’re trying to do something new you’re up against the old. But that’s what I see as the future.