Nature-based wastewater treatment in a simpler, smaller package

2024 has been a tough year for drought in Alberta. While spring rains brought relief to some parts of the province, pockets of drought remain. Drought resilience is a concern, but keeping the taps flowing is not the only issue. In fact, what goes down the drain can sometimes be a bigger challenge.

Rural communities often can’t afford a conventional wastewater treatment plant. Instead, their sewage goes into a wastewater lagoon: a constructed pond where bacteria and algae partially break down the waste products. With the help of some additional treatment, the lagoon water is safe to release into local waterways.

At least, that’s how it’s supposed to work, but drought threatens the most important part of the process: dilution.

A teaspoon of salt is fine in a swimming pool but will ruin a mug of coffee. The same principle applies to releasing lagoon water. When the receiving stream has adequate flow, any remaining pathogens or dissolved nutrients are quickly diluted to safe levels. But when drought reduces stream flow, lagoon discharge could put downstream users at risk. Drought or no drought, however, communities continue to produce wastewater, and that wastewater has to go somewhere.

With an expensive overhaul of their existing lagoons out of reach, how can small communities stay resilient to drought? Magna Engineering believes the answer is in nature-based solutions. In a project supported by Alberta Innovates and the provincial government, their team has adapted the existing Magna Biofilter Wetland System (MBWS) into a simpler, smaller version that can augment an existing lagoon.

“We thought, can we do something that would be similar but smaller scale, that can actually augment existing lagoons?” says Anton Skorobogatov, director of innovation at Magna. “Something that could be replicated at a broader scale and provide cleaner water in general to users in the province?”

The original MBWS is a constructed wetland designed to replace a traditional lagoon, sending water through a series of treatment cells that mimic the natural processes of a wetland. Each cell features a unique combination of plants and soil microbes which naturally break down the organic waste products. Using the same approach, Magna has adapted the MBWS into a smaller, easier-to-install option.

The new system offers a solution for communities working within their existing lagoon footprint. The design sends outflowing water from the lagoon through a series of treatment cells. It removes pathogens and excess nutrients like ammonia, nitrogen and phosphorus, making the water suitable for continuous discharge into the environment, even in drought conditions. The result could be transformative for small communities whose lagoons are at capacity.

“If water quality in a lagoon is not up to discharge standards, a community might be looking at trucking their effluent offsite to another facility. On top of costs, it’s logistically difficult and quite a burden for a small community to manage,” says Skorobogatov.

Continuous discharge also means the same lagoon can handle a greater volume of wastewater, allowing growing communities to extend the life of their existing infrastructure. If higher water quality standards are met, there could even be opportunities to reuse discharged lagoon water for irrigation.

“You can look at it as an end of pipe system, but it’s different when you look at it as a source water protection measure,” says Skorobogatov. “What targets do we need to meet in order for that discharge to be a good source of water?”
Support from Alberta Innovates has been an important driver for the project.

“One of the more important aspects of working with Alberta Innovates, both for Magna and for innovation in the province, is being able to move the needle on what can be done,” says Skorobogatov. “If you can think of a solution to address a need, you can find resources for implementation.”

The Government of Alberta has also had an important role in the project’s development.

“Having the right systems in place to effectively manage wastewater during a drought is critically important for our communities and our environment,” says Rebecca Schulz, Alberta’s environment and protected areas minister. “It's great to see Clearwater County piloting new technology to upgrade wastewater treatment systems in the hamlet of Leslieville to make them more drought resilient while also supporting future growth in the area."

Since starting the project earlier this year, Magna has completed the functional design of the treatment cells and is now working on detailed optimization of the design. The goal is for the system to use very little mechanical parts while still maintaining standards for water flow and water quality. On-the-ground implementation in trial communities is planned for 2025.

“We’re in an interesting space where there will only be more pressures on infrastructure and water in general,” says Skorobogatov. “Moving forward, we hope the nature-based approach gains more traction as a practical solution.”