Gone in the Wind

To manage leachate at a landfill, the operator has a few different options.

They can transport the wastewater to a treatment plant offsite, they could set up and operate a wastewater treatment plant onsite, they can use deep well injection, or they can take advantage of natural systems such as evaporation or recirculation.

In many scenarios, accelerating the natural process of evaporation can be the most efficient and cost-effective solution.

One product that facilitates evaporation is Slimline Manufacturing's EcoMister Evaporator. The system was created and patented more than 20 years ago, and it uses turbine technology to disperse water droplets into a plume, which then exposes more of the surface area of these droplets in the air, enhancing evaporation.

The air velocity reaches 100 miles per hour and allows for control over the size of the water droplets as well as the direction of the spray. This means that particle drift is minimized, and solid particles return to the leachate pond. The EcoMister also has automated electronic controls to shut down the system when winds are too strong; this keeps water droplets from being pushed outside of the containment space.

Ray Juska became familiar with the EcoMister Evaporator while serving as Manager of the Newell Regional Solid Waste Management Authority (NRSWMA) in Alberta, Canada. His work in the waste management industry began in 1996 when he was first involved in siting and design of the Newell Regional Landfill. He retired this year but had been managing staff and overall site operations at the landfill since June 2011. In addition to the Newell Regional Landfill, the NRSWMA also operates five transfer stations serving County of Newell residents.

Before adopting the evaporation technology of the EcoMister, the NRSWMA had utilized deep well injection to deal with leachate at the Newell Regional Landfill. Juska remarked that not only was this method expensive, but it was also wasteful in terms of the amount of water used. In seeking alternative solutions, they visited the nearby Pincher Creek Landfill, where the EcoMister had been installed and operational since 2016.

Because of the success of the EcoMister at the Pincher Creek Landfill, Juska said, the Newell Regional Landfill team decided to try it in mid-2020, and they have been using it ever since.

“As with any landfill, leachate is a concern. We are in a semi-arid area, so we don’t get a huge amount compared to other landfills,” he said. “Our solution up until a couple of years ago had been deep well injection. Our leachate isn’t terrible overall, but we were looking for alternatives.”

The projected life span of the Newell Regional Landfill is 50–75 years, according to Juska. “We’ve only developed half of the landfill at this point, and we’re planning two new cells this year. It will be a while before we’ll have to expand from there. “We are a member of a regional waste-to-energy project for southern Alberta. We’ve been working on that for at least 12 years. Our landfill is the chosen site, so if the project does proceed, that would certainly change things as far as the landfill capacity that we need.”

Expanding on this waste-to-energy project, he said, “Because of the economics of waste-to-energy plants, you need a lot of guaranteed waste. If you have a major metropolitan city, you’ve got it. With a regional project and a bunch of smaller municipalities, it becomes more complex.”

Juska explained that the majority of the leachate at the Newell Regional Landfill is generated from industrial waste, which is more challenging to deal with than municipal waste. The municipal waste that the landfill receives is low in volume and also relatively clean. Natural evaporation has been effective at managing the leachate coming from municipal waste. Due to the frequent crosswinds, windscreens were installed on three sides of the pond to help reduce impacts on the pond and increase the availability of the evaporator. Juska compared the advantages of the Newell Regional Landfill with those of the nearby Pincher Creek Landfill. He stated that one major advantage at the Pincher Creek Land-fill is the location. “It’s located right against the Rocky Mountains, so their winds are generally coming from a consistent direction. At ours, we get more of an arc.”

The evaporation pond measures about 70 meters by 50 meters (230 feet by 164 feet). Even with a small pond, the expense of deep well injection was a main problem that the landfill faced in dealing with excess wastewater. Deep well injection would cost at least $30 per cubic meter, and with at least 1,000 cubic meters a year, Juska said, it adds up quickly. “We decided to try a mechanical solution rather than continue with that. With deep well injection, you have no control of the costs—you’re dealing with trucking and disposal costs, which vary depending on demand and economic conditions at the time.”

When asked about the cost of operating the EcoMister, Juska said that overall the costs haven’t been expensive. “We didn’t have power supply out to our pond itself, so we had to buy a generator to operate it,” he said. A diesel generator was purchased to run the EcoMister, which has been efficient, according to Juska. “As far as operating costs, that’s the main one we have—once you get past the capital cost—the cost for the electricity to run it. In a more ideal situation, though, we would have power there to operate it.”

Juska estimates that evaporating wastewater at their landfill using the EcoMister system has saved the NRSWMA between $30,000 and $40,000 each year. He has been pleased with the performance of the EcoMister system at the landfill so far. “One component that functions very well is the intake on a skid at the bottom of the pond.

It has a rotating self-cleaning intake screen—the intake has to have a screen so you’re not sucking up debris into the nozzles. That part has worked quite well,” he commented.“We’re still not using it to the maximum of its ability,” Juska said. With the addition of the windscreens and full use of the EcoMister’s auto-mated wind speed and wind direction controls, they expect even greater returns moving forward.“You have some control; by adjust-ing pressures, you can change the particle size. It’s kind of a trade-off—the finer the particle size, the more evaporation you get, but the more drift you have. You have to have a balance.”

In 2021, operating the EcoMister contributed to additional evaporation at the Newell Regional Landfill that they would not have been able to achieve through natural evaporation alone.“It does have settings for automatic shutoff based on wind. We tried to keep it operating as much as we could,” said Juska.

“One thing you have to consider with a system like this is, depending on the nature of your leachate, if it’s more organic than inorganic, then your contamination may actually dissipate or break down as you aerate it. Our concern is mainly salt.“As the unit runs, over time, it will concentrate salt through evaporation. At some point in time, it may be necessary to dispose of some of the material by deep well injection to keep it from getting too concentrated, but that’s a few years down the road before we’ll have to worry about that.”

The biggest challenge was addressing concerns about drift. Juska recommends accounting for the wind turbulence at the site and to plan for that in designing its setup. “If you can’t run it because you’re concerned about spray getting off the pond footprint, then you’re not going to get maximum performance from the unit.” For customers with a larger pond, Juska said, the EcoMister can be mounted in the middle of the pond so that wind direction is no longer a concern.

Every site is different. When it comes to finding the best method for dealing with leachate at a landfill, consider your site’s particular challenges and requirements. The EcoMister system was the right choice for the Newell Regional Landfill as a cost-effective and efficient method of reducing leachate.

Overall, Ray Juska spoke highly of the EcoMister’s installation at the landfill. “It does what it’s supposed to do. It’s quite dramatic when it’s operating.” Another benefit for the Newell Regional Landfill is that the EcoMister is made in Canada, so they have great access to Slimline’s North American service and parts supply.