For years, the United States has managed water for the Safe Drinking Water Act as well as the Clean Water Act, resulting in a gap in the middle “that tends to ignore that the water cycle is a cycle, not a dead-end,” points out Guy Carpenter.
Carpenter is vice president and Water Resources and Reuse Practice Group leader for Carollo Engineers, a California-based water-engineering firm. He serves on the board of directors for the WateReuse Association, whose members work to improve local water supplies, and for the Central Arizona Project, designed to bring about 1.5 million acre-feet of Colorado River water annually to Pima, Pinal, and Maricopa counties from Lake Havasu near Parker, to the southern boundary of the San Xavier District of the Tohono O’odham Indian Reservation southwest of Tucson.
“We are entering an era of water scarcity,” says Carpenter. “West Texas is a great example where many communities are down to just months of supply, and they’re looking at alternatives to their groundwater and surface water and are having a hard time finding regulatory structures that would allow them to do things with other supplies such as stormwater, the effluent from a reclamation plant, or even highly contaminated or brackish groundwater supply.
“There is a regulatory gap in terms of being able to give a public water supply entity the confidence that it would need to make use of the available technology,” he points out. “In many cases, the regulatory frameworks don’t exist.”
The Safe Drinking Water Act ensures water utilities produce water that is deemed a safe, reliable supply for drinking, says Carpenter.
“In the Safe Drinking Water Act, references to surface water, groundwater, and groundwater under the influence of surface water are basically the sources for drinking water supply,” he says. “Much of the regulatory structure of the drinking water side is focused on those sources of supply.”
At GE, water conservation and reuse continues to be an important driver for end users who look for ways to use less water and make use of unconventional sources for needs such as cooling water.
Bucking the Trend
How can the US arrive at the point that closes the gap?
“It seems we start managing things when we get to a crisis rather than anticipating the fact that we’re getting close to a crisis,” says Carpenter. “When it comes up as a need is when we start developing the regulations, unfortunately.”
One state bucking the trend is California.
“Their state legislature wants to have a regulatory structure in place by the end of 2016 for making use of reclaimed water as a potable source,” he says. “I don’t think there’s been a community in California that has required that yet, but it is interesting that they are gearing up for that ahead of time. Other states have not been so proactive.”
The Groundwater Replenishment System (GWRS) project in Orange County is a success story, Carpenter says.
The GWRS–a jointly-funded operation of the Orange County Water District and the Orange County Sanitation District–purifies highly treated wastewater through a three-step advanced treatment process of microfiltration, reverse osmosis (RO), and ultraviolet (UV) light with hydrogen peroxide, producing water that exceeds all state and federal drinking water standards.
The award-winning system went into operation in 2008 as a solution to severe drought and is able to produce up to 70 million gallons of high-quality water every day to meet the needs of nearly 600,000 residents in north and central Orange County, CA. It is undergoing continued expansion.
An additional benefit: the system uses less than half the energy required to pump imported water from northern California to Orange County and other parts of southern California, and uses less than one-third the energy required to desalinate ocean water.
“Other places in the United States have been doing similar things, although maybe not with as high a technology treatment,” he adds. “It’s more of the idea of taking stormwater sources or effluent from the wastewater treatment plant directly into a source of supply right into the drinking water plant–that’s where we have the hiccup on the regulatory framework.”
How to get the public on board is the “golden question,” Carpenter points out.
“When communities get to that point where they are looking at what is possible, they need to look at all of the options,” he says. “They need to look at what it’s going to cost them to import new water supplies, and what they have legally and physically available to them. I don’t think it comes down to cost effectiveness. I do think communities–when they face scarcity issues–need to look at all of the options and decide for themselves whether or not they believe the technology will protect them.”
While engineers have a high level of confidence in the technology, “for people who are not as familiar with it, it needs to be proven to them as much as it initially does to us,” says Carpenter.
In essence, all water is recycled, he points out.
“It’s an intimacy thing,” he says. “It’s one thing for wastewater or stormwater to be discharged at point A on a stream, and then for it to become part of the natural process and be withdrawn as a drinking water supply some point downstream. For whatever reason, humans believe that there is safety in the environment. Even though we know the environment is filled with chemicals and pathogens, for whatever reason the human psyche feels better about water once it’s back into the environment or it gets used again.
“We are getting to a level of intimacy between the point A and the point B, the point where water is being put into the environment, and where it’s withdrawn is getting closer and closer, mostly due to scarcity,” he adds.
There is no prescription for any particular approach, Carpenter says.
“Every community has different water rights, different water portfolios. Obviously, somebody in the middle of Arizona isn’t going to go to ocean desalination,” he says. “It’s also a matter of engineers providing the truthful information about what the technology can and can’t do, and allowing the communities to make decisions for themselves.”
Technology to the Rescue
Graham Symmonds–chief technology officer and senior vice president for regulatory affairs and compliance at Global Water Management, an Arizona company that owns and operates regulated water and wastewater utilities–agrees that water scarcity is a looming issue that is becoming a “limiting factor for residential and industrial development.”
He also agrees that all of the world’s water is recycled.
“If you’re drinking water from the Colorado River, chances are it’s got someone else’s recycled water in it,” he says.
Against the backdrop of a lack of a regulatory framework, technology exists to help solve potable water source issues.
Russ Swerdfeger, global product manager for Memcor Membranes at Siemens, says most of the company’s work in alternative water sources has come through the hollow fiber, low-pressure membrane product line, applied in industrial and municipal settings since the early to mid-1990s.
“We’ll run municipal effluent through the hollow fiber membranes, and that usually gets processed in a secondary step by RO and, in some instances, a UV or an ionization process, depending on the final use of the water,” he says.
Memcor is utilized in Orange County’s GWRS system. The process is indirect in that a significant portion of GWRS water is injected back into the ground for seawater barrier and aquifer recharge to become part of the region’s drinking water supply, Swerdfeger points out.
Siemen’s hollow fiber membrane products also are used in pre-treatment seawater desalination using RO in three large installations in Australia.
Australia’s drought left its residents with no choice, Swerdfeger says.
“In the US, at least at this point, there are still plentiful water supplies in significant parts of the country,” he adds. “The water-stressed areas like California could probably use a few desalination plants, but they focused a lot more on the reuse side of things, really shaving off the use of potable water and going to direct reclaimed water.”
The Infrastructure Issue
Another aspect to why water reuse isn’t more widespread in the US is infrastructure, Swerdfeger points out.
“You have to put in some piping to distribute that reclaimed water into where it needs to go, and that’s when costs start to increase,” he says. “It’s a chicken-or-egg argument.”
Decentralized reclamation is a growing trend, Swerdfeger notes, referencing a Midwestern biodiesel plant that has run a line from the local municipal wastewater plant and installed its own treatment system to use the water for process water needs.
Infrastructure is the biggest challenge in implementing alternative water supplies with higher and more expensive levels of technology, says Carpenter.
“We also have aging infrastructure that needs to be dealt with,” he adds. “The biggest challenge in the future is in making sure people are willing to make the investment in their own infrastructure for their own safe, reliable water supply. Water is going to get more expensive.”
Still, agencies use and distribute their available water at the lowest cost they can secure, points out Randy Truby, comptroller and past president of the International Desalination Association.
“They all employ conservation and education programs to encourage responsible water use,” he says. “If their populations exceed the available water sources, they need to incorporate alternative technologies like wastewater recycle. If they have access to seawater, they can look to this source to expand their water supply. All over the world, from Australia to Singapore to the USA, agencies are putting together a water management plan that uses all of these options to meet their citizens’ requirements for water.”
Selecting the best combination of treatment technologies is one challenge faced in planning for alternative water sources, says Leo Zappa, director of municipal marketing for Calgon Carbon, adding that a utility’s location plays a significant role in those choices.
“If you’re located near the coast at the ocean, membrane technologies will generate a concentrated waste stream,” he says. “If you are near the coast, the same way that you see plants that use ion exchange–they have access to brine lines that go straight into the ocean–you can dispose of the concentrated waste streams from these membranes in much the same way, and that might help swing toward reverse osmosis.”
In land-locked areas, an entity may swing away from RO to something like granular activated carbon (GAC), because there is not going to be a concentrated waste stream, Zappa adds.
At GE, water conservation and reuse continues to be an important driver for end users who look for ways to use less water and make use of unconventional sources for needs such as cooling water, points out Glenn Vicevic, product management leader for GE Power & Water–Water & Process Technologies. GE’s Water & Process Technologies’ portfolio of products to treat impaired water sources for reuse includes Ultrafiltration (UF), RO, and Electrodialysis Reversal (EDR) membranes.
“Last year, we launched our Integrated Pump and Energy Recovery (IPER) system, which overcomes a significant technical and economic obstacle for larger desalination facilities by reducing the energy demands by at least 10%,” says Vicevic.
Calgon Carbon manufactures GAC, used to prevent the formation of disinfection byproducts (DBPs) and remove other organic contaminants found in surface water and groundwater.
The company also manufactures UV technology. When contaminated water is passed over ultraviolet lamps, the UV energy disrupts the DNA in viruses, bacteria, and protozoa, rendering them unable to reproduce. UV is especially effective in treating chlorine-resistant organisms such as Cryptosporidium and Giardia.
Additionally, Calgon Carbon manufactures ion exchange technology, which treats municipal water contaminated by inorganic compounds, such as nitrate, perchlorate, hexavalent chromium (Cr VI), and color. While regulatory requirements are already in place for nitrate across the United States and perchlorate is regulated in several states, EPA intends to regulate perchlorate and hexavalent chromium.
The Need for Regulation
The biggest challenge utilities face in planning and implementing systems based on alternative water sources is that while the technology is available, the regulatory framework is generally not in place. The lack of a federal regulation is a significant challenge, says Zappa.
“Presently, various states have put their own regulations in place and, in other cases, just guidelines,” he says. “Out of 50 states, I believe there are 31 that have either regulations or guidelines and can differ pretty significantly from one state to another. But that’s not the whole country, and you’re not getting any federal guidance at this point.”
Permitting is a challenge because alternative water sources for potable use is “still unchartered territory,” notes Zappa.
“Most of this work, especially reuse, is happening in only a handful of states, but if you look at the United States, two states dominate in terms of water reuse–Florida and California. Texas is a distant third, and then there’s Virginia, and maybe Arizona. But the first two lead by huge margins.”
Swerdfeger cautions that any entity looking to alternative sources for potable water “needs to pay close attention to what rules are already in place and if there are no clear well involved early in the process, to make sure you don’t get a wrench thrown into your plans.”
“There are a lot of potable reuse projects being designed and even being constructed without the regulatory framework, so the regulatory guys are doing this on the fly as well,” adds Symmonds. “In Arizona, we’re working with the WateReuse Association in trying to establish what that regulatory process needs to be.”
Some advocate the prescriptive technology process wherein specific treatment technologies are defined and proven, and others advocate performance-based criteria, says Symmonds, adding that he believes the industry will ultimately embrace a combination of both methodologies.
The “Triple-Bottom” Line
Many firms in the industry–including CH2MHill–are looking at triple bottom-line analyses of various treatment trains, Zappa says.
“The triple bottom line has come to be defined as first and foremost the actual technical performance,” he says. “You have to be able to hit the treatment objectives. Economics is a second element, and the third is the social, environmental and cultural impact.”
Zappa says some comparisons show GAC can “outperform on a triple bottom line basis” a RO-based treatment train.
“It’s not to say that GAC from a technical performance standpoint outperforms RO, treats to high levels. It does not,” he says. “But it treats to high enough levels to meet most of what has been recognized as the parameters you want to hit in treatment of water from alternate sources.”
From an economics standpoint, GAC can be 50% of the cost of an RO-based treatment train, Zappa says.
“From a carbon footprint standpoint, it can also be close to half, which I found surprising until I read some of the data that went to the argument of the electrical power required for the membrane systems,” he says. “That is detrimental to the carbon footprint of that entire treatment train. RO can be the best water quality, but in some ways it’s more than you need to meet the requirements.”
Most agencies responsible for water supply to their constituents have an overall water management program that includes conservation, water purchase, groundwater, surface water, wastewater recycle, and, in the case of coastal communities, seawater desalination, says Truby.
“These potential sources have different costs and treatment requirements and the agencies do their planning and budgeting appropriately,” he says.
When planning to use alternative sources of water for indirect and direct potable use, utilities need to think about where they’re getting the water from and what treatment technology is going to be required to achieve the target water quality they want, says Swerdfeger.
It’s important to understand the quality objective for the reused water and the impaired water contaminants, Vicevic says.
“With this information, the best solution can be identified and installed,” he says. “GE Water & Process Technologies works with our customers to determine the best system for their desired water needs.”
Planning and Implementation
“The purveyor needs to be certain they have a clear understanding of these specific regulations and guidelines,” says Vicevic, adding that GE’s team attempts to stay abreast of those regulations so when customers need to build or upgrade a facility, the company can help them understand the requirements needed to meet specific guidelines.
Carpenter points out that stormwater and wastewater has significantly high concentrations of pathogens and chemicals, “and we have to be respectful of that fact, and, in making use of those sources, we have to take a multi-barrier approach,” he says.
“In the treatment process, we have to make sure we’re paying attention to those critical control points more closely than we would if we were using a surface water supply,” he adds.
Another factor in using alternative supplies is the need to do operator training differently, Carpenter says.
“Historically, we’ve had wastewater treatment plant operators and water treatment plant operators. Now there is a need for a new advanced water treatment plant operator who is looking holistically through the whole process. Along with that training comes things we’ve never needed to use before, like checklists and online monitoring. There is a higher level of scrutiny in using alternative supplies and regularly reporting that back to the public so they have the confidence they need to make the investment in it.”
Be it wastewater, seawater, or rainwater, any alternative water supply is going to contain solids, particulate matter, and organic and inorganic contaminants, says Zappa, of Calgon Carbon. He agrees that a multi-technology, multi-barrier approach is necessary “to getting that water from a point where it came to you from these sources to where it can be used.”
There are a few treatment train models in existence, but the first task in any model is initial filtration, often a microfiltration membrane system, Zappa points out.
The second pass–which addresses smaller contaminants and chemical contaminants–entails technologies such as RO and GAC.
“Even beyond all that, you’re going to have a third line for further disinfection,” says Zappa. That usually entails a UV or ozone system; if used, GAC would come into play after ozone.
“That way, they can get huge biological activity on the carbon, which will improve its performance for removing organic contaminants,” he says.
If the intent is for direct potable reuse, “you’re looking at not going straight to the water plant or the distribution, but doing something in terms of a buffer,” says Zappa. “In some cases, that can be using it to recharge groundwater aquifers, and then it is pumped out as it is needed. That provides an additional psychological comfort, because quite frankly, there’s no reason why after the treatment train I just described that water couldn’t go straight to distribution.”
“The issue isn’t so much technical performance or level of contaminants, it’s more the public perception. That remains to be the biggest single impediment to direct potable reuse in the United States.”
Public perception is not so much a problem with desalination, Zappa says, adding permitting tends to be the major prohibitive issue.
Rainwater catchment also requires a certain level of disinfection and organics removal, depending on where the water came from when it rained and what it was exposed to, says Zappa.
Treatment and water quality monitoring are critical factors in integrating alternative water sources.
Modern membrane technology provides water that is “very high quality and safe with the kind of monitoring agencies are accustomed to providing,” says Truby. “All water agencies have their own laboratories and or access to a lab that can sample and analyze water quality. This is in addition to the online equipment that continuously measures key parameters of water quality. Additionally, many states or governments have oversight organizations that monitor the water to be sure the agencies are carrying out their duties.”
In the case where a purveyor was using a membrane, the impaired water would be separated into a treated high-quality water and a reject stream, says Vicevic.
“The treated water would be monitored for the specific contaminants of concerns either by grab sample and laboratory testing and/or an online instrument,” he says. “GE Water & Process Technologies also offers customers InSight, our remote monitoring and diagnostics platform. InSight not only connects customers with a team of GE experts, but provides them with software designed to help make timely and proactive decisions to maximize system performance and reduce costs.”
Desalination cost has been one of the factors that have prohibited utilities from pursuing desalination. “The costs of wastewater recycling and seawater desalination have come down over the last two decades, and these technologies–both of which use membranes–are playing an increasing role,” says Truby. “As populations grow globally, the demand for more water and better quality water is also pushing agencies to employ membrane technology to meet their goals.”
While most desalination plants are located in the Middle East and Australia, San Diego, CA, is in the process of constructing a desalination plant, Zappa says.
The San Diego County Water Authority expects to add desalinated seawater to its water portfolio by 2016 as to reduce its dependence on water from the Colorado River and the Bay-Delta.
RO membranes will be used to remove water molecules from seawater. Water from the ocean will be forced through tightly wrapped membranes under very high pressure, allowing smaller water molecules to pass through and leave salt and other impurities to be discharged from the facility.
Desalination facilities are presently treating brackish groundwater from the county’s underground aquifers using the same reverse osmosis technology.
The Carlsbad Desalination project is expected to produce enough water to supply 7% of the San Diego region’s water supply. Poseidon Resources, a private, investor-owned company that develops water and wastewater infrastructure, will own and operate the desalination plant and will design and build a 10-mile conveyance pipeline to deliver desalinated seawater to the aqueduct system of the Water Authority, which will own and operate the pipeline.
Indirect Potable Reuse
Indirect potable reuse “introduces some new considerations,” explains Zappa. “One of the things you see people do with the water once they treat it from the wastewater plant is re-inject it into the ground, so you’re essentially recharging groundwater aquifers.
“But what’s interesting about that is that you’ve changed the nature of what you’re bringing up out of that aquifer, so the treatment process you’re using at the tail end to treat that water coming out of the well may not be what you use when it was naturally recharging with a traditional groundwater aquifer.”
The amount of total organic carbons (TOC) is low compared to surface water, Zappa says.
“Obviously, surface water has very high levels of TOC, because you’ve got all of the organic matter running into the lake and reservoirs and the river from the leaves and the animals. You have issues with disinfection byproducts when you disinfect it with chlorine–disinfection to date has been a surface water issue. You disinfect groundwater, but unless it’s a shallow water aquifer under the influence of surface water, you don’t have much to worry about in terms of DBPs.
“But now that the water source is coming from a wastewater treatment plant, the effluent is still going to have a pretty significant organic loading to it, and then you’re going to put it into the ground and then you’re going to pull it back up–now you can see levels of TOC in that water that are not something you would see with natural groundwater.”
Not all organic matter is equal, Zappa adds. “Organic loading from a wastewater source that has been treated and put into the water is different organic matter, as opposed to naturally occurring matter,” he says. “There are hundreds if not thousands, of potential constituents, and that mix that comes through a wastewater treatment plant may be a little bit different than what happens naturally.”
Another element to consider when pumping reused water into the ground is using the correct technology to address contaminants of emerging concern, such as pharmaceuticals and personal care products, says Zappa.
“A traditional wastewater treatment process usually does not effectively hit those,” he says. “If you go to a reuse plant and further treat it until you put it into the ground or send it into distribution, and if you’ve got GAC or RO and ozone in addition to that, then you’re going to be pretty confident you’ve gotten those,” he says, adding that, for the most part, water reuse is still focused on agricultural and landscape irrigation usage.
The reduction of potable water for uses other than human consumption, such as irrigation, is the driving force for many clients of Clearwater System’s Dolphin WaterCare, a non-chemical pulse-powered water treatment solution used in multiple commercial and industrial applications.
Dolphin WaterCare’s pulse-powered technology is a low-power consumption technology that induces an electric field through the water that passes through a unit. The water treatment module is unobstructed and designed to handle high flow rate water without creating any obstructions in the water.
“As the water passes through the electric field, it creates precipitation on suspended particles,” says Anupam Bhargava, CEO. “In a normal cooling water application, precipitation typically occurs on heat transfer surfaces that leads to scale build-up, obstruction of flow, and loss of heat transfer. We changed the location of precipitation of solids coming out of solution in the water.”
That prevents scale, he adds.
Biological activity is controlled through encapsulation and electroporation, designed to provide treated water with lower biological counts than accepted drinking water standards.
“This is compelling because when you look at the cocktail of biocides used to control bacterial activity in cooling water, to be able to do it without the use of those biocides is very valuable, especially when you consider that 60% of the water that leaves the cooling tower leaves either through evaporation or drift,” says Bhargava.
“So if your cooling tower is at a hospital, a university or even a shopping center, the people in the vicinity of that cooling tower are also getting exposed to these different chemicals,” he adds.
Corrosion control is another element of a water treatment program.
Dolphin WaterCare creates a benign corrosion environment achieved by the formation of cooling water chemistry where calcium carbonate is concentrated sufficiently for precipitation to take place, says Bhargava.
He says the water treatment system offers the “sustainability benefits of water savings, energy savings, chemical avoidance, and pollution prevention, typically using whatever water that’s provided by a facility.”
Clients are exploring opportunities for the company to use for the company to use facility greywater and other discharge waters into the cooling tower as makeup water, an approach now in its early stages.
“Because we’re not introducing chemicals into the mix, that presents a whole host of benefits,” points out Bhargava. “We’ve seen customers, large and small, start taking that blow-down water from the cooling tower and repurpose it, so not only are they reducing the amount of wastewater going into the sanitary sewer or to their onsite wastewater treatment facility, they’re actually lowering their potable water consumption by reducing potable water demands for those applications such as irrigation.”
Offsetting that demand can be significant. According to Clearwater Systems, more than 10 billion gallons of water are used daily in the more than 4.9 commercial buildings in the US. Citing the US Energy Information Administration, the company points out that a typical office building uses 33% of total water demand for cooling.
Some 37% of water used in office buildings is for domestic/restroom use; 33% for cooling and heating; 20% for landscape, and 10% for other uses, including the kitchen.
Facility owners treat water to extend the operational life of expensive cooling equipment for efficiency and to prevent the spread of disease from pathogens. More than 99% of building cooling water is treated with chemicals, according to Clearwater Systems.
Bhargava contends that the problem with chemical treatment is that biocides and corrosion inhibitors have a negative effect on the environment and human health; there is difficulty in administering and balancing multiple chemicals throughout the life-cycle, and there is chemical discharge into the environment via water discharge, air emissions, spills, and drift.
Compared to traditional water treatment on a 1,250-ton system, the Dolphin WaterCare is designed to provide a drinking water and makeup water savings of 1.3 million gallons per year (MGY) with a 1.9-MGY blowdown water available for reuse.