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Collaboration and ingenuity lead to industrial wastewater solution

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Dr. Jiangning Wu, Dr. Al jibouri, Dr. Konstantin Volchek
(Left to right) Dr. Jiangning Wu, Dr. Al jibouri, and Dr. Konstantin Volchek standing in front of equipment used in the continuous advanced oxidation process developed by Dr. Al jibouri as part of his PhD research. Photo credit: Dwayne Ford, Ryerson University
By Dwayne Ford

During his Masters of Science in Chemical Engineering, Dr. Al jibouri’s university was approached by Iraq’s environmental protection agency with a problem it could not solve. Namely, how to remove high levels of chloride and sulfate ion concentrations being discharged into the Tigris River from an industrial electroplating wastewater treatment plant.

Dr. Al jibouri led a team that designed, manufactured, and installed electrodes to control the addition of oxidizing and reducing agents in the industrial electroplating wastewater treatment plant. By doing so, his team was able to reduce concentrations of chloride and sulfate ions in the effluent to permissible levels.

When Dr. Al jibouri came to Canada and began a PhD at Ryerson University, it was natural for him to pursue his interest in industrial wastewater and he turned his attention to the problem of oil sands pollution in northern Alberta.

Canada’s oil sands occupy a 75,000 km2 area that has the potential for the extraction of up to 900 billion barrels of bitumen. The alkaline hot water extraction process used to remove bitumen from oil sands results in 4 m3 of wastewater per cubic metre of oil produced. Estimates are that, by 2025, extractions underway in the oil sands will lead to 1 billion cubic metres of wastewater. This byproduct is held in settling ponds but this cannot provide long-term protection against seepage into the groundwater and the resulting environmental damage.

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The high levels of naphthenic acids in oil sands wastewater led the Alberta government to implement a zero-return policy that requires all wastewater to be stored in settling ponds rather than flowing back into the water supply. Recently, it also passed legislation requiring that all settling ponds be emptied within 10 years of the closure of a mine.

These regulations, which are critical for the protection of the environment, are accelerating the oil sands wastewater crisis. If a solution cannot be found, the oil sands industry could be shut down, which would have an enormous negative economic impact on Alberta and Canada.

The challenge with naphthenic acids is that their compounds are simply too large for microorganisms responsible for biodegradation to digest. So Dr. Al jibouri worked to discover a process that will break down the compounds in naphthenic acids to such a size that they can be biodegraded naturally.

Prior to beginning his research, it was widely known that ozone has the capacity to break down bio-recalcitrant pollutants through oxidation. The difficulty is that ozone-based processes have historically been very expensive. It has never been possible to develop a technique that would be cost-effective when applied at an industrial scale.

Guided by his supervisor, Dr. Jiangning Wu, Dr. Al jibouri undertook the development of a procedure that would allow for optimal control of ozone levels to find the minimum amount of ozone required to break down the bonds in naphthenic acids. They also set out to develop a continuous system for wastewater treatment rather than the batch and semi-batch methods that had been used before.

At the outset, Dr. Al jibouri faced a problem inherent in adopting a novel approach: starting from scratch. For example, there was nothing in the literature about the kinetics of naphthenic acids and ozone. This meant they knew next to nothing about the chemical reactions between them. Without this knowledge, it would not be possible to build an effective wastewater treatment procedure.

This absence of information meant that the first stage of the research involved the painstaking process of determining the minimum levels of ozone required to break down naphthenic acids.

Then, Dr. Al jibouri and Dr. Wu were able to build a procedure that would allow them to use both continuous ozonation processes, where only ozone is used, and continuous advanced oxidation processes in which a combination of ozone and hydrogen peroxide is utilized.

With the new mechanism and procedures established, they undertook the extensive optimal control studies required to discover if they could accurately adjust the amount of ozone used to break down the naphthenic acids.

Results

Pollution levels in wastewater are commonly measured using the ratio of biochemical oxygen demand (BOD) with chemical oxygen demand (COD). If the BOD/COD ratio is higher than 0.5, the water is “clean” enough to be treated like normal municipal wastewater.

With their continuous ozonation process, Dr. Al jibouri and Dr. Wu were able to treat wastewater so well that the outlet stream had a BOD/COD ratio of 0.52 and 93% of the toxicity was removed. With the continuous advanced oxidation process, the ratio was 0.71 and 95% of the toxicity was removed. Remarkably, it only took 2.7 minutes to reduce the toxicity of the wastewater to a level that allowed for it to be returned to the water supply.

Of even further value, Dr. Al jibouri and Dr. Wu discovered that this method can be applied in a wide range of wastewater contexts. They ran a parallel experiment with a fast-kinetic pollutant compound, methyl blue, which is a prevalent side effect of industrial dye and textile processes, and found that their procedure was equally effective. A further potential is to use the method for in situ applications such as remediating perfluorinated foam, which is used in fighting forest fires and causes groundwater pollution.

During their research, Dr. Al jibouri and Dr. Wu developed a novel approach to controlling parameters that reduced operating costs by 35% – 80%, depending on the kinetics of the compounds. These findings were so significant that they did not publish them in the dissertation and have instead applied for a patent.

As a result of their discovery, Dr. Konstantin Volchek of Environment Canada is actively engaged with Dr. Al jibouri and Dr. Wu about applying their technology to the hundreds of controlled sites across Canada where non-biodegradable pollutants need to be treated.

After conducting a two-stage evaluation process, Environment Canada has approved the advanced technology. As a result, Environment Canada has included it in the remediation technology matrix that will be presented to Natural Resources Canada, oil sands companies, and other stakeholders.

Dr. Volchek also plans to explore further collaboration with the other departments of Environment Canada to open channels to market the wastewater treatment process. Possible industrial sectors ideally suited to use Dr. Al jibouri’s water treatment process would be those which produce industrial, non-biodegradable pollutants, and engineering firms dealing with the treatment of industrial wastewaters.

Beyond its industrial applications, Dr. Al jibouri’s water treatment process could also be marketed to provincial and federal government agencies as a way to treat drinking water in some Canadian communities that are affected by non-biodegradable pollutants.

Dwayne Ford is with Ryerson University. This article appears in ES&E Magazine’s June 2017 issue.

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