Towns and cities both large and small dot the miles of shoreline winding around the waters of Lake Erie. Groundwater from beneath plenty of farms, factories, cattle feedlots, and septic systems in these heavily populated areas flows regularly into the lake’s waters.
Last summer, the residents living along the lake saw firsthand just how dangerous this could be.
The news was especially big in Toledo, OH, last August when thick beds of algae turned the water there a sickly green. Some 400,000 Toledo-area residents rely on Lake Erie water for drinking, cooking, and washing. For two days this August, though, these residents could not use their tap water. It was contaminated, marred by high levels of nitrates and phosphorus, much of it coming from sprawling farms.
Timothy Peschman, product manager for remediation at Evoqua Water Technologies, wasn’t surprised. This was just the latest, and one of the largest, algae outbreaks hitting the waterways of the United States. The truth is, municipalities across the country are frequently struggling today to control the nitrate and phosphorus that is washing into their supplies of drinking water.
The reason for this is simple: There is simply more farming and industrial activity along the country’s shorelines.
“It’s a problem that compounds itself as we do more of the agricultural things that we need to do in this country,” says Peschman. “As we add more fertilizers, we have increased the flow of nitrogen into our water supplies. The standard for how much nitrate is acceptable in drinking water has been around for a long time. But the problem seems to be more severe today simply because we are seeing so much more agricultural activity around our supplies of drinking water.”
There is hope, though. While the most popular methods that municipalities and water utilities use today to reduce nitrate levels in their drinking water come with some unfortunate side effects, big names in water treatment are working on more natural, biological means of removing nitrates from water, methods that won’t result in the high levels of waste that other treatment methods generate.
But even with the potential of new treatment methods, the best defense against nitrates and other pollution might remain one that is often the most challenging to implement: reducing the amount of nitrates that flow into water supplies in the first place.
Options
Municipalities today generally rely on two main treatment methods to reduce the nitrate levels in their drinking water supplies. The problem? Both of these methods produce too much waste water. And in parts of the country in which potable water is scarce, this waste becomes a serious problem.
The good news is that both treatment methods–ion exchange and reverse osmosis–can help municipalities reach EPA’s maximum containment level goal for nitrates of 10 milligrams per liter (mg/l).
The waste levels these methods generate, though, is concerning.
Municipalities with the single goal of removing nitrates usually turn to ion exchange. Conventional ion exchange systems, while reducing nitrates, generally produce waste volumes in the 2–4% range.
Municipalities that also need to remove Total Dissolved Solids (TDS ) from their drinking water will usually call on reverse osmosis systems that use membranes to remove both dissolved solids and nitrates from water supplies. This method is effective at removing these unwanted materials. But it also generates a lot of wasted water that needs to be flushed down the drain, from 15 to 25% of the total amount of water treated. Again, in parts of the country where potable water supplies are scarce, this wasted water makes reverse osmosis a less desirable treatment method.
And, as Antonio Inojal, applications engineer with Buford, GA-based AdEdge Water Technologies, says, in some municipalities, dealing with the wastewater created by reverse osmosis and ion exchange systems can become an expensive matter. “Some states have very strict waste discharge criteria into their sanitary sewer systems,” he says.
He also points to California, where municipalities can’t discharge the waste brine from these two treatment methods into their sanitary sewer systems. Instead, they must temporarily store this waste in a holding tank and then transport it offsite for discharge. Municipalities can also eliminate this waste in an evaporation pond. But Inojal says these are costly to build.
“Those methods of disposing of the waste brine are not inexpensive,” he adds. “Generating high amounts of waste, then, can definitely have a financial impact on utilities.”
Dow
Donna DeFlavis, technical service manager for IX Industrial Water in North America for Dow Water & Process Solutions, says that her company offers two products to help municipalities reduce nitrates in their water supply: Dow’s Filmtec reverse osmosis membranes filter out nitrates and reduce overall salinity from water. The company’s Amberlite Ion Exchange resins, which are polymeric beads, remove nitrate by exchanging Chemical Ionization ions for nitrate ions.
Both of these methods, of course, remove nitrates. But they also generate waste streams that are high in nitrate. Municipalities need to dispose of this waste. Municipalities can recover 97% or more of their water when relying on standard ion exchange treatments, though, and that’s why ion exchange technology remains the most widely used technology to remove nitrates from drinking water.
Dow offers its Advanced Amberpack technology system–a packed-bed low-waste ion exchange system that can boost water recovery up to 99.8%. For a municipality generating 1 million gallons of water a day, Dow’s system can reduce a loss of 200,000 gallons of waste water to a more manageable loss of 2,000 gallons.
DeFlavis says that Dow is now developing a new nitrate-removal process that, once it is released to the market, should provide municipalities and water utilities with another option for removing nitrates. The company’s brine-recycle process would eliminate liquid waste through the electrochemical reduction of nitrate in the waste regenerant. This would destroy the nitrate in the brine. Dow is now partnering with Severn Trent Services to develop this new treatment method.
“The majority of the cost to operate an ion exchange system is tied up in the regenerants and waste disposal,” she says. “Reducing or eliminating that waste and giving municipalities the ability to recycle the regenerant can have significant benefits.”
A Matter of Supply
The bad news? Municipalities should only expect their nitrate problems to increase over time, Peschman says. There simply aren’t as many sources of drinking water for many municipalities–especially those located in areas prone to drought conditions–to tap today.
So when the wells that these municipalities use for drinking water become contaminated, they’ll have little choice but to treat them.
“What’s happened in the past is if a municipality or drinking water purveyor has found nitrates, it’s been able to shut down the well it was using and look for another source,” says Peschman. “Or they’ve found another water source and blended water from different sources together to get to the limits they need. In the Southwest, though, the water sources are drying up. They don’t have many alternatives right now.”
And it’s not just municipalities in typically drought-ridden parts of the country that are struggling with rising nitrate levels.
“I’m in Minneapolis, and it’s been a problem here for many years, too,” says Peschman. “Iowa has had to do all kinds of different things for its water supply. It’s an ongoing problem, for sure.”
Challenges in Toledo
Water-quality issues have long been a problem for municipalities. But they don’t always make national headlines. Last August’s algae outbreak in Lake Erie, and the contaminated drinking water it caused in the Toledo area, did.
The problems in Lake Erie stem from a flood of phosphorus coming mainly from fertilizers used by farms and cattle feedlots. This turned the water of the lake green, something that made for frightening visuals on evening newscasts and in newspaper stories. But the issue of nutrients in drinking water is far from unique to Toledo and Lake Erie. In 2013, for example, phosphorus in groundwater runoff from farms across the middle of America created algae that choked the waters of the Gulf of Mexico, creating what some news sources have been referring to as an oxygen dead zone.
And the Chesapeake Bay area in Maryland and Virginia has struggled with rising nitrate levels so often that reducing these levels is a prime directive of the Annapolis, MD-based Chesapeake Bay Program.
While there are treatment methods available to water utilities, the truth is that reducing nitrates at the source, as difficult as that task might be, is the best solution for polluted water systems. It’s easier to keep the nitrates out of water sources than it is to treat them once they’ve become contaminated.
The results in the Chesapeake Bay area show this. In 2005, watershed jurisdictions in the bay area enacted a new permit process to limit the amount of nutrients that wastewater treatment plants can send into nearby rivers and streams. According to the Chesapeake Bay Program’s computer simulations, pollution controls enacted from 2009 through 2013 show that nitrogen loads to the bay from wastewater plants and combined sewer overflows have dropped by 54% since 1985. Phosphorus loads from the same sources have dropped 72%.
There remains a challenge here, though: As in most parts of the country, a large amount of the nitrates that end up in water supplies comes from non-point sources, usually industrial or agricultural users. And states and utilities have little ability to change this.
The problem is most municipalities have no regulatory or statutory powers to limit the amount of fertilizer–or the placement of this fertilizer–that farms and other agricultural users can spread on their land. And without this ability to enforce any sort of limits, states and municipalities must instead rely on agricultural and industrial users that voluntarily agree to reduce the amount of nutrients they are discharging.
It’s not that the federal EPA isn’t aware of the seriousness of the problem. In 2009, the agency, along with a variety of state-based water associations, issued “An Urgent Call to Action,” a report highlighting the increasing pollution of the country’s rivers, streams, and lakes.
But water experts say that until state and federal agencies gain real power to impose limits on pollutants such as phosphorus, waterways will continue to be at risk. Asking agricultural users and industries to enact voluntary discharge limits can help, but won’t fully address the pollution issues, these experts say.
Members of the State EPA Nutrient Innovations Task Group in “An Urgent Call to Action” write: “Current efforts to control nutrients have been hard-fought, but collectively inadequate at both a statewide and national scale.”
The task force members write, too, that the problem is certain to grow. They point to estimates showing that the US population will increase by more than 135 million people by 2050. As the country’s population increases, the rate and impact of nitrogen and phosphorus pollution will only accelerate, too, the authors say. And this could erase any progress that states and federal agencies have made in protecting the country’s bodies of water and supplies of drinking water, according to the report.
The report states, too–in no uncertain terms–that all the advanced treatment methods available won’t make a dent in water pollution if point and non-point sources of contaminants don’t act in a responsible manner:
“Sound science, technical analysis, collaboration, and financial incentives will fail to adequately address nutrient impacts at a state-wide and national level without a common framework of responsibility and accountability for all point and nonpoint sources. This framework does not presently exist.”
The report says that tools that might limit the amount of nitrates and phosphorus dumped into waterways are rarely used today. These include such tools as water-quality assessments, urban storm water controls, nutrient permit limits and animal-feedlot controls. And when these tools are used, they are often poorly coordinated or monitored, according to the report.
What would work? The task force recommends a common framework of rules that would apply to both point and non-point pollution sources across the country. The task force said that a federal overlay of rules and limits would protect those states that do want to enact tougher pollution standards.
Today, farms and industrial users not happy with their current state’s regulations can move to a nearby state that has less rigorous standards.
“We believe that absent a profound change in current approaches and support for the development of a multi-sector framework of accountability for both point and non-point sources, we are unlikely to be successful in responding to an increasingly pervasive source of pollution,” write the report’s authors.
Treating for nitrate and percholorate using ion exchange
Cooperation and collaboration
Jim Taft, executive director of the Arlington, VA-based Association of State Drinking Water Administrators, says that it always makes more sense for states and municipalities to do everything they can to reduce the amount of nitrates getting into their supplies of drinking water.
“It is far better, cheaper and easier –and more sensible–to prevent nitrates from getting into drinking water supplies than it is to treat them once they are in there,” says Taft. “The first and best course should be to take steps to keep nitrates and nutrients out of the water supplies.”
That is no easy task for municipalities, though. As Taft says, most water utilities and states don’t have the regulatory authority to prevent unwanted nutrients from coming into their water supply.
These suppliers of drinking water can only reduce the nitrates and other pollutants entering their water streams by working cooperatively with the source of these nutrients. That means working with both point and non-point sources to craft voluntary limits on the amount of nitrates and phosphorus that these users can let flow into waterways. It also means working out monitoring systems that the sources of these nutrients agree to abide by.
“What can states and water utilities do? Right now, they can mostly collaborate and cooperate,” says Taft. “The challenge is that the collaboration and cooperation must occur with the folks who are contributing the sources of nitrogen. That can be a challenge, but it’s what states and utilities must do.”
This collaboration will usually take place in steps, Taft says. First, states and utilities need to understand exactly where the excess nitrates in their water supplies are coming from. They then need to take this information to the sources of these nitrates and begin discussions with these users on what steps they can take to reduce their discharge of nutrients.
Next, utilities and state agencies need to figure out a way to treat their water supplies that already have high nitrate levels. This, again, is no easy task.
Taft says that there are some parts of the country in which voluntary measures have led to the reduction of nitrates and other nutrients in drinking water sources. But in other parts of the country, the problem is only getting worse, he states.
“Overall, this is still a big challenge,” he says. “The challenge has been exacerbated by increased temperatures in the summer and by water shortages. There are reservoirs that are shallower than they were a few years ago. The water is slightly warmer, so algae blooms are happening more frequently than before. It all makes it more challenging.”
In Ohio, where the Toledo drinking water problems made national headlines, the Ohio EPA has long advocated for stricter limits on the amount of nitrates and phosphorus that agricultural and industrial users can send into the state’s waterways.
According to a recent report by the Ohio EPA, a surprisingly high number of the state’s watersheds–48%–are degraded by nutrient loading from phosphorus and nitrogen.
“Conditions in Ohio’s surface waters have reached a critical situation,” says the Ohio EPA’s report.
To help solve this problem, the state EPA says that Ohio residents and businesses themselves will have to make changes to the way they manage agricultural and urban landscapes. Only by changing their behaviors, can they reduce the amount of nutrients seeping into the state’s waterways, the state EPA says.
US EPA has asked states to develop their own nutrient-reduction plans. Ohio’s EPA, Department of Agriculture, and Department of Natural Resources worked together to develop a statewide program for Ohio. The agencies submitted the final plan to EPA in June 2013.
The report, which comes in at 92 pages, includes several recommendations for point and non-point sources of nutrients. Some of the highlights:
- The Ohio EPA should encourage and promote operational experiments at wastewater treatment facilities designed to boost low-cost nutrient removal.
- The state government should appoint a panel of economic, financial, and policy experts to consider options for funding nutrient-reduction efforts in Ohio.
- The Ohio EPA should publish a report every year on nutrient loads and water-quality conditions throughout the state.
- The Ohio EPA should combine watershed management and green infrastructure planning with a statewide nutrient-reduction strategy.
The report, though, makes it clear that reducing the amount of nitrates and phosphorus materials in Ohio’s bodies of water won’t be an easy task.
Nitrate and perchlorate treatment system
Heidi Griesmer, media relations manager with the Ohio EPA, says that even though reducing nitrate flows is a challenge, the hard work is necessary. She says Lake Erie is a source of drinking water for 23 Ohio public water systems that serve about 2.6 million customers. Reducing nitrate and phosphorus levels, then, is a matter of public health.
“A multi-faceted, multi-year approach to reduce the discharges and runoff of nutrients is vital to protect public health, the environment, and our valuable water resources,” says Griesmer.
Griesmer says the Ohio EPA is providing funds that public water systems can use to add treatments to mitigate the toxins related to harmful algal blooms. The state EPA is also providing funds that wastewater treatment plants can use for technology that will reduce the nutrient levels in their discharges. At the same time, the state EPA is partnering with the Ohio Department of Natural Resources and the Ohio Department of Agriculture to manage the discharge of nutrients throughout the state.
A Biological Advantage?
While it’s unclear just how effective states like Ohio will be in reducing the amount of nutrients flowing into their rivers and lakes, there is some progress being made on the treatment side.
While reverse osmosis and ion exchange systems can be effective in removing nitrates and other nutrients from drinking water sources, as noted earlier, these treatment methods do generate unwelcome waste.
Fortunately, water treatment experts are developing new biological treatment methods that, if all goes well, will not only reduce nutrient levels in water supplies but also generate little waste while doing so.
AdEdge is one company working on a new biological treatment method for reducing nitrate levels, its new Biottta method.
This biological solution is designed to remove nitrate, perchlorate, hexavalent chromium, VOCs, and other contaminants from drinking water supplies. The Biottta treatment method uses naturally occurring bacteria to eliminate these contaminants.
The big selling point? This treatment method does not create the same waste streams that result from reverse osmosis or ion exchange treatments.
So far, AdEdge has run pilot programs for the Biottta method in California and Minnesota. The California Department of Public Health has approved the treatment method for the removal of nitrate and perchlorate from the supplies of drinking water in that state.
“This method can resolve the biggest problem with other ways of removing nitrates from water supplies: It eliminates all that waste,” says Chad Miller, product manager at AdEdge. “That is an important issue in many municipalities. The other treatment methods simply produce too much waste to be ideal solutions.”
Evoqua Water Technologies is also developing its own biological treatment method to remove nitrates from drinking water. Peschman says that the company already offers this biofiltration technology for wastewater clients, and that it hopes to soon offer it for drinking water.
Evoqua is currently testing the biological treatment on drinking water in Rialto, CA.
“The problem, though, is that people still think of bacteria in water as being a bad thing,” says Peschman. “Fortunately, this mindset is slowly changing. More people are realizing that there is good and bad bacteria, and that if you use bacteria to treat water, you will produce a minimal amount of waste. In drought-stricken areas, there is a definite advantage to this type of technology.”
Of course, even if companies such as AdEdge and Evoqua succeed in bringing biological treatment methods to drinking water, prevention will remain the best way to protect potable water. This means that states and utilities still need to continue to look for ways to limit the amount of these nutrients that reach water supplies.
And until states gain more regulatory powers–something that doesn’t look likely at least in the near future–the key to reducing nutrients remains, as Taft says, “cooperate and collaborate.”
“That isn’t what people often want to hear,” says Taft. “But for now, the key is to encourage point and non-point sources–and non-point sources in most parts of the country are providing the lion’s share of the nitrates that are getting into drinking water supplies–to voluntarily work to reduce their discharge of nutrients. That’s not an ideal solution, but it’s what states need to do today.”
DeFlavis says, too, that new technology will be a key tool in helping water utilities remove the nitrate from their drinking water. Fortunately, water treatment companies are working on this new technology now.
“Nitrate issues are not going to go away. They are a byproduct of life,” says DeFlavis. “We fertilize our crop fields with manure, and we raise animals for food. All of this adds nitrates to our water sources.”
