Success Stories

Making Water Purification Greener with Forward Osmosis

At Forward Water Technologies, forward thinking is more than just a metaphor. The Mississauga-based company, a for-profit subsidiary of GreenCentre Canada, has been making significant strides with its pilot technology called forward osmosis.

At a time when end users are conscious of requirements to minimize carbon footprint, the promising energy forecast of forward osmosis could be the next green benchmark for water purification. WaterTAP spoke to Howie Honeyman, CEO of Forward Water, and Lyle Clarke, Executive Advisor of GreenCentre about the welcome rise of this nascent technology, and its diverse implications across multiple sectors.

The forward osmosis alternative

“Thermally driven processes that evaporate or boil very compromised wastewater are quite energy-intensive,” Honeyman says. “Even reverse osmosis, which is an established water purification technology, has its limitations,” he says. “For instance, high levels of salt concentrate make the process energy and cost-prohibitive because greater applied pressure is required to shuttle water through the permeable membrane.”

“Conversely, forward osmosis actually entails the use of a highly concentrated of draw solution,” Honeyman says. “When a highly contaminated waste stream is placed in contact with this draw solution, but still separated by the semi-permeable membrane, a naturally-occurring, high-pressure gradient is created, which causes a spontaneous flow of clean water across the membrane without requiring an externally-applied energy source.”

“Forward osmosis essentially draws fresh water from the waste liquid into the draw solution,” he says. “Forward Water’s magic happens through a special salt to create the draw solution. After pulling out clean water, by gently heating the now diluted draw solution the salt is converted into a gas which bubbles out of the solution, leaving behind fresh water – similar to mineral water going flat,” he says. “The technology then recycles those evaporated gases to recreate the draw solute.”

The benefits of forward osmosis

GreenCentre was quick to see the potential benefits from an environment and climate change perspective. ”From a climate change perspective, Forward Water’s fundamental advantage is that it makes unusable water usable, rehabilitating highly contaminated water that might otherwise be lost forever to deep well disposal,” Clarke says.

Honeyman cites two traditional ways for dealing with wastewater: either thermal or disposal methods. In the first case, forward osmosis forecasts massive energy and cost savings. “Thermal energy that evaporates or boils water requires burning fuel to create heat, whether electricity, coal, or gas – each source creates greenhouse gas (GHG) emissions,” he says.

In addition, Forward Water’s approach can utilize low-grade waste heat from many industrial processes that would otherwise radiate out into the atmosphere, and use that energy to drive the process. “This method is unusual because compared to other water purification technologies, our process will be a remarkably low-energy treatment,” he says. “By recycling this heat to drive our process, we are not adding to the GHG footprint.”

“Current findings at the pilot plant suggest that our technology is on target to be as low as one-tenth of typical thermal energy processes,” he says.

The second method – disposal – requires transport. Currently, large volumes of industrial wastewater is so contaminated it is disposed of in deep wells. “Diesel consumption, idling time, travel to disposal wells – these all meaningfully escalate GHG levels,” Honeyman says.

“Since forward osmosis can render that water suitable for direct discharge for irrigation or groundwater all on-site, we can eliminate the need for transport altogether,” Clarke says.

Timelines and diverse applications

Forward Water’s timeline is on track for success, and Honeyman anticipates that in the next two years, the company will increase to 10-15 full-time employees. “By the end of the summer we are aiming for two important milestones: first, to substantiate our energy claims by attaining comprehensive empirical data at the laboratory; second, to validate the pilot results with our partners at University of Toronto’s Department of Chemical Engineering so that we can scale up to an industrial model,” Honeyman says.

“Our goal is to be commercially active in the industrial wastewater sector in the next two years,” he says. “We are targeting the Windsor-Montreal corridor, partly because of local proximity, partly because of high manufacturing concentration. But we will also expand from central to coastal regions where industrial wastewater is active.”

“The diverse range of potential applications is one of the reasons GreenCentre invested in forward osmosis,” Clarke says. “Long-term we aim to resolve challenging wastewater sources such as mining installations, the oil and gas sector, and, eventually, seawater desalination.”

Honeyman says that success in industrial wastewater will be sufficient for early trials in oil and gas. His five-year timeframe is to be engaged with at least a few moderately sized producers in Alberta.

“Traditional methods for removing waste are difficult, risky, and expensive,” he says. “When each producer has multiple sites producing anywhere from 10,000 to 30,000 barrels equivalent a day, forward osmosis will be a bright option toward low carbon sustainability.”

Honeyman also believes the technology will benefit the agricultural sector, especially in Alberta and the southwestern United States, which has abundant water aquifers with high saline content.

“We have already demonstrated that we can meet municipal targets for sewer discharge,” he says. “Likewise, in a rural situation, we can take wastewater from deep well salty aquifers that cannot be used currently, and convert it into water for irrigation directly. Soon enough, forward osmosis will be the new standard across various sectors.”

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