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The City of Rochester, NH, faced two problems: It was spending too much money to aerate the water in its two large wastewater lagoons, and its aeration system, more than two decades old, was starting to show its age.
For more than 20 years the City of Rochester, NH, had been relying on a fine bubble aeration system to circulate the lagoons, which, together, held 60 million gallons of water spread across 22 surface acres.
City officials decided to do something different. Instead of replacing the old aerator with the same type of system, they looked for an alternative and found SolarBee, a solar-powered circulator manufactured by Pump Systems Inc. in Dickinson, ND. The city agreed to enter into a one-year pilot program to test the circulator, to see just how effectively it could aerate two lagoons of such significant size.
So far, the results have been impressive. The SolarBees aerate the ponds effectively, with no sludge, odors, or increased amounts of algae noticeable. At the same time, the SolarBees save Rochester thousands of dollars a month in reduced energy costs.
“Whenever you can use solar power or natural power to achieve the same results, that’s a win-win situation for us,” says David Green, chief plant operator with the City of Rochester. “It benefits the city, the environment, the whole nine yards. We’re very excited about this. As we get farther and farther into the study, it seems to be working. So far, so good.”
Green and Rochester officials aren’t the only ones who have experienced firsthand the improving technology in the often ignored world of wastewater aeration. Manufacturers are constantly updating their products, always improving them or adding new features.
This is good news to those who run wastewater treatment plants. As aeration technology improves, it’s easier for these officials to keep their lagoons, ponds, and reservoirs healthy and clean.
Saving Dollars in Rochester
Joel Bleth, president of the SolarBee division of Pump Systems Inc., says that the future looks brighter than ever for aeration technology.
He should know. His company—already considered an innovator because its circulators rely on solar power—is adding even more technological improvements to its line of products.
During the last two years, SolarBee engineers have been equipping the company’s circulators with both supervisory control and data acquisition (SCADA) software and GPS technology. This allows clients—including those treating wastewater—to monitor their circulators from computers located at their desks.
SolarBee is also adding digital control technology to its products. This means that clients can input different data and performance requirements depending on the type of environment in which their circulators are operating and the goals these products have.
For example, aerating circulators operate differently in a pond covered by shade than they do when they’re moving water around a pond that sits in open sunlight. SolarBee provides a flashcard that is about the size of a quarter. Operators stick the flashcard into the circulator’s operating system and program the aerators to perform exactly as they see fit.
Monitoring systems, Bleth says, are an innovation that can help make life easier for those who must operate wastewater treatment systems, whether traditional, decentralized, or clustered.
For example, a SolarBee is circulating the water in a pond located in an urban area. If the pond doesn’t have any protective bar screen, several types of debris can end up in it, including paper bags, chunks of carpet, and who knows what else. If too much of this debris is kicked up by the circulator, it can jam the circulator’s impeller.
By logging onto the SCADA system, an operator can see that the circulator is kicking itself into automatic reverse mode in an attempt to clean the propeller system every 15 minutes. The operator can then clean the system himself, allowing the circulator to operate at its most efficient level once again.
As the aerators that circulate water, reduce odors, and cut down on algae improve in quality and offer more features, property owners will find that their lagoon systems will remain an attractive option when treating wastewater, Bleth says.
“There are huge numbers of these lagoon systems that are doing a very good job and would be very expensive to replace in rural areas,” he explains. “We are seeing a realization in these small cities that they need to keep improving their lagoon systems. They need to have better maintenance, better aeration, and more consistent removal of biological oxygen demand and ammonia.”
Bleth and his fellow SolarBee officials are currently working on ways to help lagoon owners reduce the levels of ammonia in their water. This is especially tricky in cold climates, where it’s difficult to generate any significant reduction of ammonia in the winter.
SolarBee is now experimenting with a technique that involves carving out a small section of a large lagoon that can better retain heat. The company then moves all aerators into that section. Such a small sub cell at the front of a lagoon system seems to result in the more efficient removal of ammonia.
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Photo: Solar Bee |
| A SolarBee can be quickly installed from the back on an ordinary pickup truck. |
“You may have a lagoon system where you think you need a $5 million sludge plant because you can’t remove enough ammonia,” Bleth says. “Well, we have some ideas on that.”
In Rochester, city officials are thrilled that companies like SolarBee are willing to innovate. Thanks to the city’s new pilot program involving SolarBee circulators, Rochester is saving about $11,000 a month in aeration costs. That’s because the existing fine-bubble aerators that had been circulating water in two of Rochester’s large wastewater treatment lagoons had cost that much in energy each month to run. With the SolarBee, the city has been able to leave off the 125-horsepower motors that powered that system’s blowers. In all, the city hasn’t run a blower since April 2006.
“This is very preliminary. The project is still a pilot program,” Green says. “But still, $11,000 a month is a significant amount of savings.”
Rochester began running its pilot program in April 2006. Officials there hoped not only that the SolarBee would save them money but that it would be likewise effective in keeping the lagoons’ water clean and aerated.
So far, the city has seen good results on its end, too.
“We want to be a good neighbor,” Green says. “One of the criteria for acceptance of this product is that after one year, there can’t be any odor complaints. We didn’t want to cause a lot of odors and drive our neighbors nuts. This summer was a good test. We had some periods of hot, humid, and dry weather conditions, which would tend to keep those odors. But we haven’t had one odor complaint. That was positive.”
Green also had hopes that the SolarBee would be effective in removing sludge from the lagoons. So far, that appears to be a success, too.
Wastewater officials have tested the lagoons and have seen no negative changes in the amount of sludge in them.
Green is now waiting for one more challenge: He’d like to see how the SolarBee performs during the coldest days of winter. He’d like to see the circulators do their work after a layer of ice forms on the lagoons.
“We’d like to see the SolarBees running in all four seasons,” Green says. “We want to make sure the treatment works as well in the winter as it has in the past. That way, we’ll have a more accurate idea of how the SolarBee can work for us.”
Of course, Green is far from alone in relying on improved aeration technology to keep his bodies of wastewater clean and odor-free. It’s a challenge wastewater engineers have long faced.
Fortunately, with today’s class of aerators, it’s a challenge that’s easier than ever to meet.
Easier to Use
One of the most important technological advancements made by aeration companies is one that’s often overlooked. Today’s aerators are easier to install and operate. This is key: No matter how effective a product is, wastewater officials won’t use it if it causes too many headaches.
Doug Cramer, president of Air-O-Lator Corp. in Kansas City, MO, knows this. Air-O-Lator manufactures fountains, aerators, mixers, and aspirators. The key feature of his products? They’re easy to work with.
Air-O-Lator products are designed so there is no assembly required, Cramer says. Clients merely place the flotation unit in position, anchor it, set the Air-O-Lator unit in place, run the power cord, and install the control panel. After that, turning on the machine is all that’s left to be done.
The simpler the better, Cramer says, especially for municipalities that are still small but growing. Instead of having to create new wastewater treatment facilities and systems, these towns can instead install aerators to help keep their ponds and lagoons clean.
Because aerator manufacturers are constantly working to make their products more efficient and easier to use, Cramer says, more municipalities are turning to the products for their wastewater-treatment needs.
“I don’t think it’s a matter of people being more understanding of the need for aeration. I really think it’s a matter of this being something they have to do,” Cramer says. “You have to keep the mix up or the aeration up. Commonly, you have to do both. Otherwise, you will have obvious odor problems, and you’ll have poor waste treatment in a facility, whether a concrete tank or a lagoon-type surface.”
Air-O-Lator has thrived by serving niche markets, mostly industrial clients. Its mixers, for instance, work well for systems that feature aeration chambers and tanks that also need mixing. Air-O-Lator’s mixers are designed to move large volumes of water to combat the sludge that aeration sometimes leaves behind on deep tanks.
“Whenever you have a concentration of waste, whether from humans or animals, it has to be treated,” Cramer says. “It has to be treated either by Mother Nature or by enhanced means if the loading is great enough so that nature can’t treat it by itself.”
Increased Focus
Manufacturers have been inspired to improve and tweak their products in large part because government agencies are taking a closer look at aeration.
Bob Robinson, director of sales and marketing for Prescott, WI–based Kasco Marine Inc., a maker of aerating fountains, water circulators, and beneficial bacteria, says that a growing number of states are requiring that the operators of wastewater plants include plans for aerating their retention ponds.
The reasons are many, Robinson says. First, municipalities want wastewater officials to control the amount of algae in their retention ponds. Second, they want to prevent the unnecessary deaths of fish, something that happens too frequently when pond waters don’t contain enough oxygen.
Another reason states are requiring aeration measures is because aerators help reduce the odors that come from ponds. Finally, when water circulates at the surface, breaking the surface tension there, it interrupts the larvae stage of the mosquito lifespan.
Even with more attention being paid to aeration, there is still room for improvement, Robinson says. He’s looking forward to the day when he no longer has to justify the costs of installing and operating an aeration system.
“We are considering ways to help speed the education process,” Robinson says. “We think holding seminars might be a better way. The problem is getting people to attend. We have to make it attractive enough for them to attend, for them to pay attention. If aeration measures are mandated into law, that will change things even quicker. You’re darn tootin’ that they will pay attention to aeration then.”
Ken Rust already is paying attention. He’s the owner of Absolute Aquatics in Walker, LA, and spends a great deal of his time installing aerating fountains and circulators in retention ponds or recreational ponds in the Baton Rouge area.
Rust says that increased aeration provides a host of benefits to the ponds his clients are maintaining, some more apparent, others less obvious.
For instance, when pollution such as pet feces, grass clippings, leaves, or even petroleum from cars driving down the street get into a pond, water that runs through an aerating fountain breathes better. That goes far toward eliminating the gases from these pollutants.
Rust and his company have installed a 2-horsepower fountain in the retention pond of the South Haven subdivision, a residential housing project in Walker developed by national homebuilder D.R. Horton Homes. Previously, the retention pond featured a low-flow fountain. The fountain was attractive, but it clogged easily and wasn’t pumping the amount of water necessary to aerate the pond sufficiently.
The new fountain, though, does pump enough water to properly aerate the pond. It also helps prevent any buildup of organic materials such as algae blooms. The aerator breaks the surface tension of the water, too, meaning that the pond looks fresher. From an aesthetic point of view, as the pond’s surface tension continues vibrating, the pollution—dust, pollen, leaves, and other materials—sinks.
“They do like the fountain we’ve installed,” Rust says. “It shoots up a 20-foot-tall display. It’s a nice landmark for selling houses. At the same time, it keeps the pond clean. It keeps housing prices up, too, because water is always a big focal point. Too often, developers plop these ponds down in these neighborhoods without giving any thought as to how they will impact real estate value. They forget that these ponds need to be maintained. If they’re not maintained, if they’re ignored, they can quickly become an eyesore.”
A Growing Need
Mike McGee, president of EP Aeration in San Luis Obispo, CA, says that he expects demand for aerators and mixers to increase in the coming years.
The reason? Developers—residential and commercial alike—aren’t about to stop building housing subdivisions, shopping malls, and industrial parks.
And these developers will often place their new projects on land that is located far from any urbanized areas.
“As developers begin disturbing more rural areas, more riparian areas, they are becoming more aware of how important it is to provide proper aeration,” McGee says. “We do an awful lot of golf course lakes and ponds, for instance. When they build a golf course, they need a lot of water, a lot of storage. Generally, they have irrigation ponds. A great many don’t have any circulation at all. They can very quickly become stagnant and have problems with odor and appearance. Most new developments are mandated to use tertiary treated wastewater for their irrigation, so that extends a whole other set of problems to the picture. There’s just a growing need for aeration measures.”
EP Aeration serves a wide range of customers, everyone from those running large reservoirs of drinking water to those maintaining golf course lakes and ponds. The company’s fine-bubble, bottom-laid aeration system is also used in the lagoon systems run by wastewater treatment plants. Marina operators even use it; the tubing in the bottom-laid aeration system helps keep water from freezing up around boats.
EP Aeration’s system is another example of how aeration technology has improved, and today offers wastewater officials a wider range of options for keeping their ponds and lagoons algae-free and clean. With weighted tubing keeping the system at the deepest parts of a body of water, EP Aeration’s aerator sends off a gentle flow of air bubbles rising to the water’s surface. The system circulates a large amount of water while expending little energy. This is important for municipalities, which are always looking to save as much money as possible.
“We are not causing turbulence that can lift bottom sludge,” McGee says. “That’s the main thing. We are circulating water without disturbing the sludge layer. By having a low-horsepower expenditure, we can run it 24 hours a day, circulating a tremendous amount of water.”
New Applications
Most people think of aerators as doing one job: circulating water to prevent the buildup of unwanted algae and chemicals.
It’s true, that’s what they usually do. But Dean Caldwell knows that these machines can do a whole lot more.
Caldwell is president of Airmaster Aerator in DeRidder, LA. He says that many of his clients have found added benefits with his company’s high-capacity aeration products.
For instance, Airmaster aerators are now in place at a busy steel mill in Chicago. Officials there rely on the aerators to reduce the heat—which can become unbearable quickly—at their mill. These aerators have allowed the mill’s operators to forego purchasing a multimillion-dollar cooling tower, saving the mill money while also keeping their wastewater lagoons clean.
Caldwell says that the circulation and spray of the aerators work together to reduce the heat in the facility. A cooling tower would have cost the mill about $7 million, Caldwell says, and would have guaranteed it a temperature drop of no more than 2 degrees. Each one of Airmaster’s 50-horsepower units achieves at least a 1-degree drop. The mill, then, was able to spend about $500,000 in aeration units to gain a 10-degree drop. That’s a bargain compared to $7 million for 2 degrees.
Airmaster was also able to use its 50-horespower units to reduce the amount of ammonia in the flash lagoons at a large power plant. The company provided the plant with seven of the units to aerate a 75-acre lake that was 45 feet deep. The units raised the oxygen levels significantly enough to reduce the lake’s ammonia levels.
This is important; the plant, which Caldwell couldn’t name because of confidentiality agreements, has to add ammonia to its lagoons. But it must reduce these levels of ammonia before discharging any gas in order to meet discharge standards.
“We’ve been able to go into different applications—heat reduction, ammonia reduction—and do things that are completely out of the box as far as standard aeration goes,” Caldwell says. “Where we excel is when the water is really bad. Anybody can go in and aerate decent water and achieve a result. But we tackle the challenging bodies of water.”
Airmaster even used its aerators to help in the emergency cleanup of the Gulf Coast following Hurricane Katrina. The company provided 28 of its 25- and 50-horsepower units to help reduce the contamination of water being pumped out of New Orleans.
“We had our units in all the major pumping stations,” Caldwell says. “When we got the units back, they were all completely covered in barnacles, showing the absence of pollution. It definitely showed that we cleaned up the water that they had pumped out of the city.”
Dan Rafter is a technical writer based in Illinois.
OW - March/April 2007 |
