June 2, 2021

Cleaning up contaminated land using tools from nature

Canadian Environment Week:
Partnership seeks solutions for brownfield sites

 

A photo of Dr. Paolo Mussone at a brownfield site, courtesy of NAIT.

Dr. Paolo Mussone at a brownfield site, photo courtesy of NAIT.

Researchers at the Northern Alberta Institute of Technology (NAIT) are developing a renewable product to help clean up tens of thousands of sites across the province contaminated by petroleum products – locations like old gas stations, fuel storage sites and other so-called “brownfields.”

Monitoring site remediation

Typically, site remediation is monitored by consultants who periodically tap into groundwater, collect water samples, and take them back to a lab to analyze the level of contamination. This testing process is expensive, costing tens of thousands of dollars each time, says Dr. Paolo Mussone, Applied Bio/Nanotechnology Industrial Research Chair at NAIT.

In a project that received a $383,000 investment from Alberta Innovates, the NAIT researchers developed a sampling device that contains another forest-related bioproduct called CNC (cellulose nanocrystals), as part of system to monitor how land remediation is progressing over time at contaminated sites.

They coated a white disc about the size of an M&M candy with CNC and deployed it in wells at the test sites. They found that the CNC absorbed hydrocarbons and allowed bacteria to attach and degrade these contaminants.

This project also involved the deployment of remote electronic sensors to determine the rate at which the hydrocarbon contaminants had biodegraded by monitoring Ph levels, temperature of the soil and other measures. The remote sensors can provide multiple data points at far less cost than traditional monitoring methods. NSERC, industry and NAIT also contributed funding and in-kind contributions to this project for a total of $780,000.

The next step is further refinement and field-testing of the CNC-based system.

The researchers have found an innovative use for a natural compound from trees called lignin. First, they developed a product they call “lignochar” using a special chemical process to convert the lignin. Then they added lignochar to contaminated soil. It provided nutrients to naturally occurring soil bacteria that flourished and consumed the hydrocarbon contaminants.

Instead of the traditional method for site reclamation – digging out contaminated soil and dumping it elsewhere – this technology remediates the land and makes it usable through an organic process. It’s an environmental and economic win-win, says Dr. Paolo Mussone, Applied Bio/Nanotechnology Industrial Research Chair at NAIT, who heads the lab where the research took place.

Lignin product biodegrades contaminants

Lignochar is designed to be added to the soil in situ (at the site) to accelerate the biodegradation of the hydrocarbon contaminants at a fraction of the cost, he says.

“Typically, soil is excavated and taken to landfill. But all you’re doing is taking a problem from one site and moving it somewhere else,” says Mussone about the most commonly used method to remove hydrocarbon contamination from brownfield sites.

“The reason why we have 30,000 contaminated sites in Alberta is because it’s so expensive to remediate them,” he notes. “The value of the real estate tied up in these sites is in the billions of dollars. It’s a significant lost economic opportunity.”

Lignin is one of the most abundant organic polymers (molecular compounds) on the planet. It’s the compound in trees that provides structure and strength to wood. Lignin is separated from wood fibre as a byproduct during the pulping process.

Because it is so plentiful, scientists in many countries have been searching for ways to isolate lignin for industrial applications. In 2015 West Fraser Timber was the first company in Canada to scale up the production of lignin at the company’s mill located in Hinton, AB, with funding support from Alberta Innovates.

Lignin’s extraordinarily versatile chemistry makes it suitable to create value-added bioproducts as part of the circular economy. Since 2018, Alberta Innovates has partnered with West Fraser and NAIT in providing $169,000 in funding out of a project total of $240,000, for the researchers to investigate the chemical transformations of lignin at high temperature and high pressure. Aspects of this work have shown it is possible to synthesize highly porous particles made from lignin capable of absorbing hydrocarbon fuels.

The NAIT researchers, who also include Drs. Victoria Collins and Weizheng Shen, showed lignochar is effective in the lab at bench scale, are now planning further optimization of the chemistry in collaboration with West Fraser, Federated Co-operatives, and the United Farmers of Alberta, as part of a project funded by the National Science and Engineering Research Council. This work aims to scale up the chemistry synthesis process and test the new materials in the field.

Alberta Innovates investment critical in proving concept

Alberta Innovates’ investment in the NAIT work was critical in proving the initial concept idea of a lignin-based solution to clean up hydrocarbon contamination. These early findings were the basis for attracting additional funding from NSERC (Natural Sciences and Engineering Research Council of Canada), doubling the total research investment to about $500,000.

n addition to the economic benefits for landowners of contaminated sites, finding applications for lignin can provide new revenue streams for the forestry sector – an economic driver for Alberta that accounts for about $4.5 billion of annual GDP, employs more than 13,000 people and serves as the backbone for 50 rural communities.

Technology for in situ land remediation is still in its infancy and these projects have been a long-term investment for Alberta Innovates and its partners. “It has taken five years of patience, nurturing and work to get it to this stage. It’s not a quick return,” Mussone says.

But with 30,000 sites to clean up in Alberta alone, there will be a market here and potentially elsewhere for this lignochar bioproduct developed in our province. The commercialization of lignin-based advanced biomaterials will contribute to economic diversification and generate new manufacturing and engineering services jobs.

 

Forestry byproducts for the oilpatch

What is a waste in one industry can be very useful in another.

In the quest to find bioindustrial uses for forestry byproducts, Dr. Paolo Mussone has developed a unique application for the oilpatch. He has found that fly ash from pulp mills can be used to scrub poisonous hydrogen sulfide from natural gas, often referred to as sour gas commonly found in oil and gas drilling.

Mussone and his research colleague Dr. Jean Cai found that fly ash is also effective in removing hydrogen sulfide at wastewater treatment plants. According to this 2019 article in the Journal of Sustainability, pulp mills in Canada produce more than a million tons of fly ash each year, from burning wood biomass to provide heat in their operations, and disposing of the ash is a real problem for this growing industry. “Updated environmental regulations have tended to restrict the landfilling of fly ash due to rising disposal costs and the scarcity of suitable land.”

Building on this work, with an investment from Alberta Innovates for $120,000,Mussone and his team have also demonstrated the use of fly ash to sequester carbon dioxide from natural gas, adding another option to turn a problem waste into a money-maker and money-saver.

With funding from Ovintiv Inc. and NSERC, the NAIT researchers are developing and optimizing fly ash chemistry, and how to turn fly ash into pellets industry can use to sequester carbon. Their goal is to validate this concept in the field in 2022.