Forward Water proves economic viability of forward osmosis Zero Liquid Discharge

Forward Water Technologies’ industrial-scale pilot plant proves that low-cost Zero Liquid Discharge water treatment is now economically viable – thanks to a novel two-phase forward osmosis process and Aquaporin Inside® Forward Osmosis membranes.

Deep in the oil & gas heartlands of Alberta, Canada, Forward Water is doing something that could change the water treatment landscape forever. The company’s two-phase forward osmosis water treatment pilot plant is taking heavily mineralized and salty industrial water and producing clean and reusable water at a fraction of the cost of anything that’s been done before.

“All the results we’re seeing so far indicate that this could be a game-changer in water re-use,” says Forward Water CEO Howie Honeyman. “Our plant is reclaiming very heavily polluted industrial water and producing almost distillation quality drinking water, with low energy use and capital costs, and a reduction in waste output of 60-70% or more. Right now, the plant is operating with water from oil & gas production, but it will work just as well in other industries.”

The Zero Liquid Discharge challenge

Water scarcity is a huge issue in our world today, listed by the World Economic Forum as one of the largest global risks in terms of impact that the world is facing. As a result, many industries are under increasing pressure from consumers, regulators and investors to shift towards a more sustainable use of water. The ultimate goal is Zero Liquid Discharge (ZLD), in which all wastewater is cleaned and recycled.

ZLD is already possible. But it is also extremely resource consuming. Treatment requirements depend on the application, but ZLD often includes ultrafiltration, reverse osmosis, various other membrane technologies, evaporation and crystallizers. In most cases, the energy alone required to drive these processes adds huge costs to a company’s OPEX (operating expenses) and usually outweighs the sustainability benefits of reclaiming the water.

This is the challenge Forward Water has overcome. The company’s pilot plant is cleaning oil & gas flow back water and produced water – some of the dirtiest water in any industry – while consuming very little energy. In fact, according to Howie, it could operate on almost any low energy source, such as waste manufacturing heat, low pressure steam – or even a remote solar thermal set-up – making it less expensive and significantly more sustainable than current water treatment processes.

The Forward Water pilot plant has demonstrated a capacity of 15 m3 of wastewater per day. Forward Water is now looking to design a much more compact unit that could fit into a single shipping container, providing a smaller footprint than most other treatment systems. (Photos supplied by Alberta Innovates)

The secret is in the saline solution

Unlike reverse osmosis, which uses energy-consuming hydraulic pressure to drive water through a filtration membrane, forward osmosis uses natural osmotic pressure. Put simply, you have feed water (the water you want to clean) on one side of the membrane and a heavily saline draw solution on the other. Because water likes salt, the water in the feed solution will move across the filtration membrane until the feed solution become concentrated and the draw solution becomes diluted.

The diluted draw solution can be used directly in other industrial processes or sent to a secondary separation process – such as evaporation – to separate the clean water from the salt. And this has always been the Achille’s heel of forward osmosis. Even after this initial cleaning, evaporation is still energy-consuming and expensive. Forward Water’s solution is the solution itself: A unique draw solution that converts into gas with just a small amount of heat – secondary heat from an existing industrial process, for example – leaving behind pure, clean drinking water.

Lower costs with the Aquaporin Inside® membrane

Howie and his team developed the pilot plant to test the Forward Water solution on an industrial scale. After initial results, most elements were performing within expected parameters. But one surprised everyone – the performance of the Aquaporin Inside® membrane. Performance was so good, it made one complete part of the plant redundant – which will significantly reduce CAPEX (capital expenses) and OPEX for future customers.

“Everything we looked at when designing the plant told us that even the best-performing membranes on the market will leave you with some reverse salt flux – salt that travels back through the membrane into the feed solution. This is no ordinary salt; it’s expensive and we need to get it back, so we built in a brine scrubbing process. But the performance of the Aquaporin Inside® membranes was so good, we didn’t get any significant reverse salt flux. In future designs, we can eliminate the salt scrubbing equipment altogether,” Howie explains.

According to Michael Holm Møller from Aquaporin, the higher performance of the Aquaporin Inside® membrane is down to its selectivity. The membranes are covered in a thin layer of aquaporins – the proteins responsible for transporting water in all living cells. The aquaporin proteins make the membrane extremely selective to water only, while ensuring unwanted compounds are rejected.

“Membrane performance has long been a problem in forward osmosis applications and installations – our membranes have been designed to overcome those problems,” he explains. “They minimize reverse salt flux and have extremely high rejection, which means the recovered water is extremely high quality .”

Making sustainable water a sound investment

At the end of the day, water re-use is about much more than CAPEX and OPEX – it’s about ensuring everyone in the world has access to good, clean drinking water. Water scarcity may mean that companies have to switch to ZLD solutions whatever the cost. Solutions like Forward Water’s will mean that decision also makes good business sense.

“In Canada, there appears to be no shortage of water. But this is unusual. Water’s becoming scarce across the globe at an alarming rate,” says Howie. “We have to find ways of converting water that’s been used in industrial processes back into reusable water. This is one of the most pressing problems of our time – and it’s really exciting to be part of the solution.”

Michael agree: “A lot of industry leaders are very motivated to come up with more sustainable solutions, but all too often the costs outweigh the gains. This is a solution that is both sustainable and economically beneficial.”

Find out more

You can find out more about Forward Water’s two-phase forward osmosis solution at forwardwater.com. To find out more about Aquaporin, visit aquaporin.com.

About Forward Water

Forward Water Technologies is an independent company dedicated to the commercialization of its proprietary forward osmosis technology. The company was founded by GreenCentre Canada and is based in Ontario, Canada.

About Aquaporin

Aquaporin A/S is a global water technology company located in Denmark. Its Aquaporin Inside membranes combine state-of-the-art engineering with the latest biotechnological techniques to improve filtration speed and efficiency.