#ColoradoSprings is exploring solutions to blue-green algae blooms

Mechanism of operation of the SolarBee system. Graphic credit: Environmental Science & Engineering

From The Colorado Springs Gazette (Liz Henderson):

Warmer temperatures and higher nutrient levels in the water have led to more blue-green algae blooms, which are harmful to humans and potentially deadly to pets, said Erik Rodriguez a Health, Safety and Environmental specialist with the city. The daily temperature record in Colorado Springs has already been broken five times this year.

While the city struggles to find a fix, other Colorado towns have used environmentally-friendly machinery that helps aerate the water. Better circulation gives algae less chance to accumulate.

In the Green Ridge Glade Reservoir in Loveland, sit five SolarBee units — solar powered machines that float in the middle of the lake. They keep the water in the reservoir moving, disrupting the stagnant environment that blue-green algae likes, said SolarBee regional manager Dave Summerfield. Each unit costs about $40,000.

Since the units were installed two years ago, the 150-acre drinking water reservoir has been free of algae.

In the past, the popular method among water treatment agencies was to dump algicides such as copper sulfate into the water. But the solution wasn’t sustainable, said Summerfield.

The bacteria would slowly adapt to the sulfate, forcing maintenance to use more and more of it, racking up costs and dangerous toxin levels…

Rodriguez pointed out that several Colorado Springs lakes already have aeration features in them. Monument Valley Park ponds have a few aerators — devices that create small air bubbles to push the water around. Mary Kyer Park has a fountain in the middle that helps with circulation, he said.

Cyanobacteria, which causes the blue-green algae, thrives off nutrients in the water, specifically nitrogen and phosphorous. Nitrogen and phosphorous get into water in runoff from agriculture, fossil fuels, fertilizers, yard and pet waste, even soaps and detergents. The city’s recent warm weather and heavy thunderstorms haven’t helped, Rodriguez said.

Longmont suspends fluoride dosing until supply test results come in

The water treatment process

From The Longmont Times-Call (John Spina) via The Colorado Daily:

“We haven’t fluoridated for about a month,” said Bob Allen, the city’s director of operations public works and natural resources. “The water supply does have fluoride in it from natural sources, but it’s not fluoridated to the recommended 0.7mg/L level since we ran out.”

Without any added fluoride, Longmont naturally has a 0.2mg/L of fluoride in its water supply.

The effectiveness of adding a chemical like flouride to water systems has recently come under some scrutiny due to a higher use of fluoride by way of oral health products like toothpaste and mouth wash. The Center for Disease Control and Prevention even reduced the recommended level of fluoridation from 1.2 to 0.7mg/L in 2013, but that hasn’t swayed the Longmont City Council to change its policy.

“The benefits outweigh the negatives,” Mayor Brian Bagley said. “So there have been no discussions to stop fluoridation.”

Currently, the city pays roughly $40,000 a year for the chemicals as well as the labor to apply it to the water system.

Jim Kaufman, the city’s water treatment operations manager, said there is a steady supply of fluoride coming out of China, but in the past he has questioned its quality and is awaiting test results from Denver Water before he uses it in Longmont’s system.

‘Greywater’ Could Help Solve Colorado’s Water Problems. Why Aren’t We All Using It? — Colorado Public Radio

Graywater system schematic.

From Colorado Public Radio (Michael Elizabeth Sakas):

Colorado was the last Western state to legalize greywater usage in 2013. Officials say that by 2050, our water supply could fall short for over one million people. Climate change makes the future of Colorado water even more uncertain.

Colorado’s Water Plan wants to close the gap and recognizes greywater as one tool to help make that happen. However, not a single state-approved greywater system has been built since it was legalized. Only Denver, Castle Rock and Pitkin County have adopted the code, known as Regulation 86, that regulates how greywater gets done in the state.

Avery Ellis isn’t happy about that. He was closely involved when the Colorado Department of Public Health and Environment set the rules.

“It takes a little civil disobedience and a little public support to push these laws into local adoption,” the greywater installer said.

In his yard in Longmont, there are young trees and shrubs that are watered through one of his greywater systems.

Longmont isn’t Denver or Castle Rock and it’s nowhere near Pitkin County. In addition to his water saving rebellion, Ellis teaches and helps others how to go greywater without a permit. Because so far, even in the places where it’s been adopted, no one has even applied for a greywater permit.

Not a single one.

In Colorado, only two types of greywater systems are legal. This first one is called “laundry to landscape.” The second is more complicated and costly. Wastewater from a shower or sink is collected in a storage tank and is used for the landscape or to flush toilets. There’s internal plumbing and the water needs to be filtered and treated and can’t be stored for more than 48 hours…

There’s been some interest in these water saving systems in Pitkin County, which adopted greywater in 2018, but environmental health manager Kurt Dahl thinks that “due to the complication of the regulation they didn’t see the benefit.”

[…]

The city of Castle Rock is the newest to adopt the state’s greywater rules, but only for new construction. Retrofitting an old home or building isn’t allowed. Mark Marlowe, the director of Castle Rock Water, cites cost as the contributing factor behind that decision…

That doesn’t mean it won’t ever happen, Marlowe said, but they don’t have the resources to allow just anyone to put in a greywater system.

And that’s why some cities and counties have chosen not to take on greywater at all. Douglas County said it would be too complicated and costly for the county to oversee. They also point to the potential for public health risks.

Boulder won’t either, at least right now. Joe Taddeucci, the city water resources manager, said they first need to study if adopting greywater is worth it. One major concern are water rights. Does the city have the OK to use greywater on lawns, instead of sending it back to the river for the next user downstream? How much water would actually be conserved? And what would it take to regulate this?

…One of the only examples of a large-scale greywater system in the state is a dorm at the University of Colorado Boulder. Williams Village North was built with plumbing that collects wastewater from showers and sinks to flush toilets. Since the city of Boulder hasn’t adopted greywater, the system operates under a research exemption.

“Testing for chlorine levels, alkaline levels. And greywater systems of this size and magnitude are still fairly new technology, and we do want to make sure that we understand it better before we implement in a new building.”

At peak use, when students are in school and the dorm is full, the system uses about 2,000 gallons of greywater a day to flush toilets. It’s an example of where some of the biggest year-round savings can happen.

Sybil Sharvelle, an associate engineering professor at Colorado State University in Fort Collins, has been involved in greywater research for nearly 20 years. She also advised the state on the rules and is disappointed to see all the growth and construction over the past 10 years has failed to include greywater.

Arkansas Valley Conduit update

From High Plains Public Radio (Abigail Beckman):

Chris Woodka is with the Southeastern Colorado Water Conservancy District. He said part of the reason we’re seeing more water systems violate water standards is that federal and state standards have changed. They are now accounting for even more minute quantities of contaminants.

He said water from wells can be especially affected because, “shallow wells in the alluvial aquifer are high in organic contaminants, nitrate and selenium.”

“Deeper wells often have elevated levels of radioactive materials,” he said. “And nearly all of the communities east of Pueblo take water from wells.”

Some communities have responded by using water filters. Las Animas and La Junta have both installed large reverse osmosis membrane systems to remove contaminants from the water supply. Woodka said that has improved the taste and appearance.

But, he said, even after filtration, radium and uranium can still remain in the water at low levels.

And then there’s the cost.

“Those communities still face tremendous expense in disposing of the waste from the treatment processes,” Woodka said, “which can only be reduced by adding more clean water.” And extra water, let alone clean water, is hard to come by in a drought-prone state like Colorado. But there is one possible solution that’s been in the works for decades.

It’s called the Arkansas Valley Conduit.

Arkansas Valley Conduit Comanche North route via Reclamation

The U.S. Bureau of Reclamation describes the conduit as a “bulk water supply pipeline designed to meet existing and future municipal and industrial water demands in the Lower Arkansas River Basin.”

It would include about 230 miles of buried pipeline, a water treatment facility, and water storage tanks. Water would be routed to six counties – Pueblo, Otero, Crowley, Bent, Kiowa and Prowers – and would serve an estimated 50,000 people.

The project was first approved in 1962. Some work was completed in the early 1980’s, but the actual conduit has yet to come to completion. Woodka said that’s mainly because of cost.

“[These] communities could never afford to build [the conduit] themselves.” Woodka explained.

Congress passed a law in 2009 that reduced the amount of money local governments would have to pitch in for the project. Woodka said that finally made the construction of the conduit feasible.

But it’s still a $500 million project.

“The main problem that we’ve run into,” said Woodka, ”has been getting adequate federal appropriations to start building it. He said they are working on ways to lower the overall costs of the project.”

Woodka said lawmakers at the state and national level have been “extremely active” in promoting this project on both sides of the political spectrum…

[Republican State Senator Larry Crowder] said the key now is for residents to get involved.

“We’re getting the cities involved, we’re getting the people in the cities involved to send letters to Senator Gardner, Senator Bennet and Congressmen Buck and Tipton,” he said, “to make sure that they are aware of how the people feel about it.”

Southern Utes approve hefty rate increase for water, wastewater users — The Durango Herald

Photo credit: Ute Camp in Garden of the Gods – Library of Congress

From The Durango Herald (Shannon Mullane):

The Southern Ute Indian Tribe Utilities Division will raise water and wastewater rates by more than 90% and 50%, respectively, starting Oct. 1.

The Southern Ute Utilities Division, administered by the Southern Ute Growth Fund, provides both treated drinking water and wastewater treatment for the tribal campus, local tribal members living near Ignacio and the town of Ignacio. Discussions of rates have caused a rift between the town and the tribe, said Mark Garcia, interim town manager. While the town and the tribe analyze their agreement, ratepayers are stuck paying ever-increasing water and wastewater utility rates.

“Wastewater and water rates are based on usage, and they’re going up,” Garcia said. Utility customers will be hit with the increase at different times, based on their level of use for water and/or wastewater. But for overall water and wastewater rates, “all levels of users will see probably an increase in their rates starting in 2020,” he said.

Starting Oct. 1, ratepayers will pay higher base rates for fewer correlating gallons of water. Water rates will increase from $32.80 per 8,000 gallons to $47.80 per 6,000 gallons, a 94% increase. The rates will jump again Oct. 1, 2020, to $62.80 per 6,000 gallons, a 156% increase over current rates, according to a July letter to Garcia from the tribe.

The town charges customers additional fees for billing, repairs and collections. Garcia said the town’s water fees will increase from $24.60 to $26.48 a month starting Jan. 1, 2020, a 6.4% increase.

Wastewater rates will also increase. Service users currently pay $72.09 per ERT, or Equivalent Residential Tap, per month. One ERT allows for 7,500 gallons of usage.

That billing system will change. The tribal utility will charge the town based on winter usage, not ERT. This shift will also make ratepayers pay more for fewer gallons. On Oct. 1, the rate will increase to $87.09 per 6,000 gallons, a 51% increase over current rates. Wastewater rates will jump again in 2020. Users will be charged $102.09 per 6,000 gallons, a 77% increase over current rates.

The town charges an additional $9.88 base rate to users for billing, repairs and collections.

According to Garcia, the average town customer uses 4,000 gallons of wastewater per month, so ratepayers are paying for more wastewater than they are using.

“With the new rates and winter flow basis, the rates that the tribe charges the town as a bulk customer will actually go down from the current bulk rate charged,” the tribe wrote in a June news release.

Scientists reveal key insights into emerging water purification technology — @ColoradoStateU

Left represents an omniphobic membrane, and right represents a conventional hydrophobic membrane with increased water-air interfacial areas (green lines). Credit: Kota lab

Here’s the release from Colorado State University (Anne Manning):

With water scarcity a critical challenge across the globe, scientists and engineers are pursuing new ways to harvest purified water from unconventional sources, like seawater or even wastewater.

One of those researchers is Tiezheng Tong, an assistant professor in the Department of Civil and Environmental Engineering, whose lab is studying an emerging technology called membrane distillation.

Membrane distillation involves a thin, water-repellant membrane that exploits vapor pressure differences between hotter impure liquid, called “feedwater,” and colder purified water, called “permeate.” During the process, water vapor passes through the membrane and is separated from the salty or dirty feedwater. According to Tong, membrane distillation works better than other technologies like reverse osmosis, which can’t treat extremely salty water such as desalination brines or produced water from hydraulic fracturing.

While it holds promise, membrane distillation doesn’t work perfectly. A key challenge is designing membranes to purify water efficiently while ensuring zero contamination of the clean water.

Tong and materials scientist Arun Kota in the Department of Mechanical Engineering joined forces to get at the fundamental science behind designing that perfect membrane. In new experiments they describe in Nature Communications, the CSU engineers offer new information into why certain membrane designs used in membrane distillation work better than others.

“The fundamental knowledge from our paper improves mechanistic understanding on the water-vapor transport within microporous substrates and has the potential to guide the future design of membranes used in membrane distillation,” Tong said.

How it works

In membrane distillation, the feedwater is heated, separating the pure and impure components by differences in volatility. The micro-porous membrane is a key component to the setup because it allows water vapor through, but not the entire impure liquid. Typically, the membrane is made of a “hydrophobic,” or water-repellant, material in order to let only the water vapor pass through but maintain a barrier for the feedwater.

However, these hydrophobic membranes can fail, because the feedwater, such as shale oil-produced water, can have low surface tension. This low surface tension allows the feedwater to leak through the membrane pores, contaminating the pure water on the other side – a phenomenon called membrane wetting.

Previous research had unveiled that using “omniphobic” membranes – membranes that repel all liquids, including water and low surface tension liquids – keep the vapor/water separation intact. But, omniphobic membranes typically slow down the rate and amount of water vapor passing through the membrane, dramatically reducing the efficiency of the entire process.

The CSU researchers set out to discover why this tradeoff between hydrophobic vs. omniphobic membranes exists. Through systematic experiments in the lab led by postdoctoral researchers Wei Wang in Kota’s lab, and Tong’s graduate student Xuewei Du, they found that conventional hydrophobic membranes create a larger liquid-vapor interfacial area. This increases the amount of evaporation taking place. With the omniphobic membranes, they saw a much smaller liquid-vapor interface. This explains the difference between the membranes’ performances.

The omniphobic membranes used in the experiments were made without depositing extra particles. Thus the researchers were able to determine that their observations weren’t the result of structural changes to the membranes.

Cross-sectional view of a conventional hydrophobic membrane used in membrane distillation. The blue represents water. Credit: Tong and Kota labs

Solving the tradeoff problem

While they didn’t offer a solution to the tradeoff, their insights reveal the core challenge around making membrane distillation a successful technology. “If you understand the problem thoroughly, then there is scope for solving it,” Kota said. “We have identified the mechanism; now we have to solve the tradeoff problem.”

For example, smart membranes with exceptional omniphobicity and simultaneously large liquid-vapor interfacial area can render membrane distillation a robust and cost-effective process for water purification. More collaborative research has been initiated by the team to design such smart membranes, with the goal of increasing efficiency of membrane distillation.

Tong added that the research happened at the interface of two disciplines: surface science and membrane technology.

“Arun and I utilized our complementary expertise to systematically conduct this work,” Tong said. “It is an example of good interdisciplinary collaboration across campus.”

Graduate students Hamed Vahabi in mechanical engineering and Yiming Yin in civil and environmental engineering also contributed to this work.

“This is an example of #climatechange in our own backyard. The reasons there are more algal blooms is because the temperatures are slightly warmer every year” — Ed Hall #ActOnClimate

Cyanobacteria. By NASA – http://microbes.arc.nasa.gov/images/content/gallery/lightms/publication/unicells.jpg, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5084332

From 9News.com (Marc Sallinger):

The City of Greeley said algae is to blame for bad-tasting drinking water in the city.

Recent hot weather caused algae blooms in two lakes where Greeley gets its water.

Lake Loveland and Boyd Lake provide more than 20 million gallons of drinking water to the City of Greeley every day. The algae bloom left that water tasting like dirt and metal.

“People don’t like water that tastes dirty,” said Ed Hall, Assistant Professor Department of Ecosystem Science and Sustainability at Colorado State University.

The blooms happen when there are nutrients in the water, hot days and not much wind…

Algae releases byproducts that cause the water to taste and smell strange. Right now, Greeley’s water department said the byproducts released from the algae are 250 times stronger than usual.

“This is an example of climate change in our own backyard. The reasons there are more algal blooms is because the temperatures are slightly warmer every year,” said Hall. “This isn’t going to go away. We really need to start thinking about how to protect ourselves and live with these as the earth becomes warmer every year.”

[…]

The city said they are now treating the water to try and get all the taste and smell from the algae out of the water. They said it should be almost back to normal by the time it gets to your sink.

From The Greeley Tribune (Cuyler Meade):

When the roughly 40 million gallons per day of potable — or drinkable — water consumed by Greeley residents started tasting and smelling noticeably different last week, the Water Department didn’t wait long to react. The department believes its swift response last weekend has effectively solved the problem, and Greeley water should now taste better.

The problem: Concurrent algae blooms in both Boyd Lake and Lake Loveland, the major peak-months water sources from which the department draws and treats the water delivered to Greeley…

That meant, Chambers said, that the option of turning off sourcing from one of Boyd Lake or Lake Loveland — from which much of the area’s water is drawn during the “peak” summer months — was not sufficient. While the department did end up turning off its delivery from Lake Loveland, where Chambers said it was determined the algae situation was “about four times” as bad as it was in Boyd Lake, the water coming from Boyd Lake was still affected with an unappealing taste and smell…

The solution, then: Increase the activated carbon used to treat the water at the Boyd Lake treatment plant.

“Activated carbon is a good way to remove (the poor taste and smell),” Chambers said. “It’s also very expensive, and it’s hard to get the dosage exactly right for the amount that we’re measuring, which is in parts per billion. Tiny, tiny molecules that have a fair amount of influence on taste and odor…

Normally, activated carbon is used to treat the water in the 25 to 27 milligrams per liter range, Chambers said. But this dual algae bloom required more.

“Last Friday, we turned off our Lake Loveland supply, which allowed our activated carbon dosage to do a better job pulling those odor-causing molecules out,” Chambers said. “Then we upped the dosage, as well.”

Chambers said they began treating the water with about 35 milligrams per liter, up about 40% from the normal dosage. The department is continuing to use that increased dosage for the time being.

“Our internal sampling has led us to believe that’s perfectly adequate for removing what’s needed,” Chambers said.

The more southerly lakes become critical sources of water in the high-usage summer months, but the “workhorse” treatment plant is actually at the Poudre River Basin in Bellvue.

“We treat our water at those two locations near the foothills where you can grab higher-quality source water than you can find in Greeley and deliver the water to Greeley,” Chambers said. “Visionary system that was developed in the early 1900s up at Bellvue.”

Chambers emphasized the fact that even before treatment, while the water may have tasted differently, it was at no time unsafe to drink.