This story originally appeared on U of T Engineering News.
Wastewater from a mine doesn’t sound like a cozy habitat, but for untold numbers of microorganisms, it’s home sweet home. A new research project led by Professor Lesley Warren (CivE) will examine how these microbes make their living by studying their genes — an insight that could help further reduce the environmental footprint of the mining industry. The $3.7-million endeavour is funded in part by Genome Canada through the Large Scale Applied Research Projects (LSARP) program.
Extracting valuable metals such as copper, nickel and gold from rocks, which typically contain only a few weight percent metals, requires substantial amounts of water. All wastewater generated must be cleaned to strict federal guidelines before it can be discharged back into the environment. It is these wastewaters that the microorganisms studied by Warren and her team thrive in.
“These wastewaters contain a variety of sulphur compounds that certain bacteria can use for energy,” says Warren, who holds the Claudette Mackay-Lassonde Chair in Mineral Engineering at U of T. “Their ability to do so evolved billions of years ago, long before more complex life arrived on the scene. If the history of Earth were a 24-hour clock, they have been around for over 23 hours, while we humans have been around for only 17 seconds.”
However, our ability to investigate these bacteria and most importantly how they are cycling these sulphur compounds, which will influence the quality of mining wastewaters, has been very limited until now. If these sulphur compounds become too concentrated, the company has to implement costly chemical treatment systems to make the water acceptable for release and avoid toxicity problems in lakes or streams downstream from the mine.
Warren believes that genomics can help. She has spent years travelling mine sites from Canada to South Africa to better understand the sulphur geochemistry of their wastewaters and how bacteria are implicated. “I have always preferred dirty water to clean,” she jokes.
For this project, Warren and her team will apply genomics directly in tandem with comprehensive geochemical analyses and modeling to wastewaters. She will collaborate closely with Professor Jill Banfield, a trailblazer in environmental genomics at the University of California, Berkeley, Professor Christian Baron, a microbial biochemist from the Université de Montréal, and Dr. Simon Apte, a research scientist in analytical chemistry and geochemical modeling from Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO) Land and Water in Australia, to unravel the role played by these sulphur-loving microbes in important geochemical processes affecting mining wastewaters.
“Mining companies know that microorganisms are driving these reactions, but its still a black box” says Warren. “The lack of available technologies has meant that there has been little research to determine which bacteria are doing what, which ones could serve as early warning signals, or those that could actually be used as the biological treatment itself. Most importantly, mining companies don’t know which levers to pull to control the system.”
Those levers are what Warren and her colleagues aim to identify. Informed by genomic and geochemical insights they plan to develop new tools that can help mine managers make better decisions about how to manage their wastewater. “Once we understand the microbes and how they affect wastewater geochemistry, we can pinpoint the drivers of their behaviour: Which wastewater compounds are they using? Do they like it hot? Do they like it cold? We can adjust those drivers to design new processes that do what we want them to do. Essentially we are mining the bacteria that already exist in these wastewaters as a biotechnology resource.”
With this new knowledge, mines could ensure conditions that encourage the growth of organisms that break down toxic compounds, or prevent the growth of organisms that produce those toxic compounds in the first place. The team is collaborating with three Canadian mining companies, as well as two engineering consulting firms, Advisian and Ecological and Regulatory Solutions. In addition, the Mining Association of Canada, the Ontario Mining Association and CSIRO are further supporting the project.
The project also has the endorsement of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM), the leading not-for-profit technical society of professionals in the Canadian minerals, metals, materials and energy industries. CIM National Executive Director, Jean Vavrek, commented: “CIM are in full support of this exciting new project. While genomics itself is relatively new to the mineral resource industry, it has the potential to provide significant returns and generate new areas for investment in the sector. We consider this a flagship project and will continue to follow Dr. Warren and her team closely as they pioneer genomics research for mine wastewater characterization and possibly treatment.”
“The mining industry has driven this project from its inception because they want to reduce their environmental footprint. Harnessing the biological potential of their wastewaters will facilitate the development of such strategies to achieve this goal,” says Warren. “So many of the organisms we’re finding are new to science. The chances that we are going to find organisms that are capable of doing creative things that could be useful are very high.”
The University of Toronto student chapter of the Canadian/National Electrical Contractors Association (CECA/NECA) is one of three finalists to compete at the 2016 Green Energy Challenge in Boston this weekend.
The students from U of T Engineering are the only Canadian team, and will compete against teams from Iowa State and the University of Washington. The final three were selected from 14 proposals.
“We selected UTS because it is an aging building that uses older lighting systems and could benefit greatly from an upgrade,” said Dmitri Naoumov (CivE 1T5+PEY), the team’s project manager. “The school is also planning a major renovation, so our proposal could help to inform the energy needs and improvements.”The U of T team partnered with University of Toronto Schools (UTS), a Grade 7 to 12 university preparatory school in downtown Toronto, to design an energy efficiency upgrade, including a small-scale photovoltaic system that would serve as a teaching and learning tool for students.
Competing alongside Naoumov are Matheos Tsiaras (CivE 1T5+PEY), Ernesto Diaz Lozano Patiño (CivE 1T5+PEY, MASc Candidate), Greg Peniuk (CivE Year 4 + PEY), Arthur Leung(ChemE Year 4), Claire Gao (ChemE Year 4 + PEY), Mackenzie De Carle (CivE Year 4) and Nataliya Pekar (CivE Year 4).
“The lighting in the rooms was below the recommended levels for classroom learning,” said Naoumov. “By increasing the light in classrooms, we are helping to create an environment more conducive for students and teachers.”Their design includes detailed technical solutions for classroom lighting retrofit, integrated window treatments and the design of a rooftop 4kW photovoltaic solar array, which all meet the unique needs of the building and the climate in Toronto. By upgrading the lighting system to use lower wattage bulbs, using occupancy sensors and installing light shelves that regulate daylight, the team determined that UTS could reduce its annual energy consumption by up to 125 MWh, or enough to light 10 typical homes.
UTS is eager to incorporate the students’ energy efficient and technologically savvy infrastructure into its daily operations. Because many Toronto public school buildings are showing their age, this could serve as a model for future upgrades across the city.
“UTS is an Eco School and we aim to reduce our environmental footprint and energy costs,” said Philip Marsh, vice-principal of UTS. “The team’s analysis and understanding of how to improve the efficiency of our building was impressive. We see the proposed roof solar array as a viable design option for the future.”
Competing for the first time at the Green Energy Challenge in 2015, the U of T team placed fourth with its lighting and back-up power retrofit proposal for the Good Sheppard Ministries shelter in downtown Toronto. Although the project did not win them a spot at the convention, Good Sheppard Ministries is currently implementing their design throughout its facility.
CECA/NECA brings together electrical contractors across the country to share experience and advice. Established in 2014, the U of T chapter extension is the first of its kind in Canada. Its goal is to bridge the gap between contracting and engineering and engage students with first-hand, applied experience. In addition to pitting their design savvy against groups at other North American universities, the group hosts networking and social events and connects students with scholarship and job opportunities.
Researchers aim to prevent a Flint-like crisis from happening in Canada
An interview with Prof. Robert Andrews, Sarah Jane Payne (Post-Doc) and Aki Kogo (MASc Candidate).
In 2014, the city of Flint, Michigan, switched its water source from Lake Michigan to the Flint River. Inadequate treatment and reporting caused lead (Pb) contaminated drinking water to be delivered to Flint residents, resulting in a state of emergency being declared.
Researchers at the University of Toronto’s Drinking Water Research Group (DWRG) have been actively studying the behaviour of lead (Pb) in water distribution systems since 2012, with a particular focus on southern Ontario drinking water sources.
“The problems in Flint emerged because the alternate water source had a slightly different water chemistry that disturbed the protective lead (Pb)-scale on the existing lead (Pb) pipes,” said Prof. Robert Andrews, a principal investigator with the DWRG. “Short of replacing all the lead (Pb) service connections in the system immediately, it will take time for the damaged scale on the interior of the pipes to build up with time and repair itself.”
Sarah Jane Payne, U of T Post-Doctoral Fellow, explains that scale (the buildup of materials lining the inside of water pipes), much like rust, can be relatively stable. However, it can cause significant issues when disturbed, as it was with the water change in Flint.
“Municipalities add different chemicals, called corrosion inhibitors, to the local water, which react with dissolved lead (Pb) in the water and re-deposit it on the surface of the pipe to form the scale,” Payne describes. “Each water source (lake or river) has a different chemistry, such as alkalinity, pH and inorganic carbon, which affects how the corrosion inhibitors react.”
“The crisis in Flint highlighted what many people take for granted,” said Andrews. “Researchers are aware of real-life issues and through careful experimentation are always looking for unintended consequences. Asking ourselves if we make one change, how is this going to affect something else?”
The science of inhibitors
As far back as the fourth century B.C.E, the ancient Greeks preferred terracotta pipes over lead (Pb). They knew, even then, that lead (Pb) negatively impacted health. Today, we know lead (Pb) is a powerful neurotoxin with serious implications for neurological development in children. Despite this, lead (Pb) has persevered as a material for pipes due to its durability and ease of use. Lead (Pb) service lines, connecting the water main to the home, were widely employed in North America until the early 1950s, when regulations ended the use of lead materials for new lines.
Municipalities today use a variety of methods including the application of corrosion inhibitors, like orthophosphate and zinc-orthophosphate, to reduce the amount of lead (Pb) consumed by the general population. These chemicals react with lead (Pb) to form a compound that precipitates out of solution to form a stable, crystal-like lining on the inner surface of the pipe. The lead (Pb)-scale is very thin – only a few microns thick.
The problem can be made even more complex when considering physical disturbances, changes or fluctuations in water chemistry, and seasonal changes in temperature, which can loosen existing scales and disrupt the chemical balance between the water and the pipes.
Utilities try to form the strongest scales possible given varying water chemistry. Local water quality conditions dictate what needs to be changed or added to reduce corrosion.
“When phosphate-based corrosion inhibitors are used, lead (Pb)-phosphate scales become more and more stable over time,” said Andrews. “Understanding that chemistry and timeline is actually quite complex.”
“Reducing corrosion isn’t just about adding corrosion inhibitors. It can also be about changing the attributes of the water itself, such as adjusting the pH,” said Payne. “It is being aware of these details, looking at them holistically that determines what combination of attributes and additives might lead (Pb) to the least amount of lead (Pb) in drinking water.
Study: Comparing inhibitors
Researchers with the DWRG wanted to compare corrosion control options for Lake Ontario water using the two most common corrosion inhibitors: zinc-orthophosphate and orthophosphate. However, as phosphates are a finite resource, sodium silicate was also selected as a non-phosphate-based inhibitor to research.
“Phosphates are expensive and the price is volatile, so we wanted to include an alternative. That’s why we looked at sodium silicate,” said Payne. “Sodium silicates’ corrosion inhibitor properties have been known since the 1920s, but the funny thing is that no one really knows exactly how they work. So we compared it to the performance of phosphate-based inhibitors to try to understand more about this corrosion inhibitor.”
To fully understand how Lake Ontario water will interact in local water distribution systems, lead (Pb) pipes that had been in use for 65 years were sourced. To simulate a scenario where a homeowner has not replaced their portion of the water service line, a partial lead (Pb) service line replacement was set up in the DWRG laboratory.
“All of our test pipes came out of a community in Ontario. When you think about these pipes, many have been underground since the 1940s. They’ve had decades of different chemical combinations pass through them,” explained Payne. “What their particular scale is formed of and what conditions keep them stable is not well understood. We use real lead (Pb) pipes that have been pulled out of the ground that we know have a history. We can do more realistic experiments with those because using a new lead (Pb) pipe would be a totally different story.”
“Both phosphate-based inhibitors performed very well, though zinc-orthophosphate did seem to perform a little better,” said Aki Kogo, MASc Candidate. “Initially, the sodium silicate did not do very well but later in the experiment we started to see some better results with it.”
Now that testing has wrapped up at the DWRG lab, this setup of lead (Pb) testing equipment will be moved to a municipality’s water treatment facility for future studies.
“It’s through a lot of hard work by smart people that this research gets done,” Payne said. “Just to get the water every week, Aki and Jim Wang [DWRG Research Chemist] transported 500 litres of ‘untreated’ water back to the tanks in our lab. There is so much physical work, time and intellectual dedication that goes into research like this.”
The impact of research
“People in the water industry are very passionate about public health and that’s always at the forefront of any water treatment research,” explains Andrews.
“What we do every day affects millions of people. Our research is done quietly, but it’s really quite important. There are strong researchers in Canada, who are truly focused on the health of Canadians and those around the world.”
Public health plays a significant role in directing the research on drinking water quality.
“There’s the epidemiology and toxicology side that drives the health-based inquiry,” said Payne. “The engineering side looks into accomplishing what is required to meet the standards set by health-based researchers. It is a back and forth iterative process that helps regulators set standards that municipalities must meet.”
“In Canada, we have a lot of utilities that are forward thinking,” explains Andrews. “It is extremely rare for a municipality to change its water source. Because of the safeguards in sampling and reporting that we have in Canada, along with the conscientiousness and vigilance of water treatment personnel, it is very unlikely that a Flint-like emergency situation will happen in Canada.”
About the Drinking Water Research Group
The Drinking Water Research Group (DWRG), formed in 1998, is a consortium of researchers from the University of Toronto. The group operates as a team working to improve drinking water quality through sound research and engineering. With over 25 ongoing projects, the DWRG typically undertakes collaborative projects examining treatment, distribution, compliance and innovation to meet future water needs. Unique resources, including a large number of municipal and industrial partners, allow for various issues to be examined.