Minerals and metal are the building blocks of the smartphones and computers we use every day, of the vehicles that transport us and of the buildings we live and work in. Mining is a major pillar of British Columbia’s economy, generating over $8.6 billion annually and employing over 29,000 people (Steilo 2012). Many mining operations utilised water for mineral processing, metal recovery and dust control. However, the use of water in mining has the potential to negatively affect the quality of the surrounding surface water and groundwater. Contamination with high concentrations of metals, sulfide minerals or salts can increase the mortality, reduce health, reproduction and number of species in aquatic ecosystems (Lottermoser 2010). Moreover, serious impacts on human health can occur where water used for drink, irrigation or industrial applications is affected (Lottermoser 2010).
The community of Trail, BC has battled pollution from Teck Metals since 1975 (Hume 2016). The community is afflicted with contaminated landfills, slag deposits that leach into waterways and a substantial plume that has spread beneath the city and the Columbia River (Hume 2016). Children from the community have also demonstrated elevated levels of lead in their blood (Hume 2016). Unfortunately, First Nations communities are among the most vulnerable populations when it comes to water contamination. At least two-third of all First Nation communities in Canada have been under water advisory at some time in the last decade (Levasseur and Marcoux 2015). Particularly, Alexis Creek First Nation, Nazko First Nation and Lake Babine, all in British Columbia, have water problems spanning 16 years (Levasseur and Marcoux 2015). The current project is aimed to meet the needs of these communities by developing a new method for water remediation.
Copper is essential in the human body for optimal function. It is a cofactor for many enzymes, as well as a key component of cross-linkages in melanin and collagen. In Canada, the majority of us don’t have a problem with excess copper in our water, therefore it is not at the forefront of most people’s minds on a daily basis. So why do we care about copper? According to the UN, 783 million people worldwide live without access to clean water for everyday uses such as drinking, cooking, and cleaning. The water they have access to comes from contaminated reservoirs containing dangerously high concentrations of copper and copper ions. That’s the global scale, now lets look at an example a little closer to home. The Mount Polley tailings pond breach on August 4, 2014, spilt 4.5 million cubic metres of slurry into Polley Lake, which later flowed into Quesnel lake (Government of BC, 2014). This disaster compromised the water quality for thousands of people downstream who rely on the Quesnel River, as the river brought many of the heavy metals with it. This is a very important example to demonstrate that high levels of copper in water are a problem for the entire world, not just underdeveloped nations. This global reality has prompted the development of new, large-scale, cost-effective water treatments for high levels of copper that are efficient and effective. We believe that using the tools of synthetic biology, we can work towards a solution of the oft-overlooked problem of copper in water, both on the local and global scale.
"Mount Polley tailings pond situation update", Government of BC, Newsroom, 8 August 2014, retrieved 8 August 2014
Lottermoser, B. G. (2010). Mine wastes Characterization, treatment and environmental impacts. New York, US: Springer.
Steilo, S. (2012, January 23). B.C. Celebrates Soaring Exploration Expenditures. BC Gov News.Retrieved from http://news.gov.bc.ca.
Levasseur, J. and Marcoux, J. (2015, October 14). Two-thirds of First Nations have been under at least 1 water advisory between 2004 and 2014. CBC News. Retrieved from http://www.cbc.ca.
Hume, M. (2016, January 28). Teck Metals to plead guilty over pollution in Trail, BC. The Globe and Mail. Retrieved from http://www.theglobeandmail.com.
Although many bacteria require low concentrations of heavy metals, high levels of copper and other heavy metals can be toxic to many bacteria including E. coli. Previous research has indicated that copper may induce the formation of free radicals, which can cause damage to the cell (Rodriguez-Montelongo et al. 1993). This poses a problem when attempting to use E. coli to remove heavy metals from water. It is possible to bypass this problem by using the protein YiaT anchor system designed by Han and Lee to bind and sequester copper outside the cell (2014). YiaT is a surface protein in E. coli. Han and Lee discovered that when truncated at the arginine residue 232 (R232), the Pseudomonas lipase could be fused to the new C-terminal end of YiaT to make a functional fusion protein (2014). Using this anchor system, it is theoretically possible to place a copper binding protein, or any other heavy metal binding protein, to the outside of E. coli.
1. Rodriguez-Montelongo L, de la Cruz-Rodriguez L C, Farias R N, Massa E M. Membrane-associated redox cycling of copper mediates hydroperoxide toxicity in Escherichia coli. Biochim Biophys Acta.1993;1144:77–84.
2. Han, M.J., Lee, S.H. (2014). An efficient bacterial surface display system based on a novel outer membrane anchoring element from Escherichia coli protein YiaT.
Currently, the removal of copper from water is accomplished through a slew of methods ranging from large-scale and industrious technologies to small-scale household friendly products. These technologies can be grouped into three overarching categories: chemical remediation, phytoremediation and microbial remediation. Although each of these methods is successful to a degree in removing copper from water, none exist without detrimental pitfalls (Akpor & Muchie, 2010).
Chemical remediation encompasses chemical precipitation and ion exchange. Both of these methods are readily available for commercial use however, they require corrosive chemicals, and produce large volumes of toxic sludge which must be treated and removed. The treatment-removal process is challenging in an aqueous environment and extremely costly. Furthermore, the solubility of metal hydroxides poses the problem of precipitating one heavy metal out of solution, and another back in due to their individual maximum precipitation pH’s (Akpor & Muchie, 2010).
Phytoremediation includes phytodegradation, phytoextraction, hemofiltration, phytostabilization and phytovolatilization. Although these methods are generally the most economical, and low in technology costs, they all involve plant growth, which render disadvantages due to dependence on growth conditions, requirement of large-scale agricultural equipment, and knowledge, long remediation timelines and potential environmental harm due to leaching of soluble contaminants (Akpor & Muchie, 2010).
Currently the most effective method of remediation is the use of chemical adsorbents, for example commercially activated carbon, which has a very high and restrictive cost associated with it; this makes it far from a globally attainable solution for copper removal (Bhatnagar & Sillanpaa, 2010). Therefore, our team has chosen to take the microbial remediation approach, which demonstrates advantages in environmental friendliness, cost effectiveness and self-sustainability. Our team is investigating methods of copper binding in order to contribute to the promising advancement of this remediation method. The current problems our team and other scientists face, which we hope to overcome, include possible and more persistent toxins than the parent microbe, as well as scaling bench top successes to a large industrial scale.
Akpor, O. B., & Muchie, M. (2010). Remediation of heavy metals in drinking water and wastewater treatment systems: Processes and applications. International Journal of Physical Sciences, 5(12), 1807-1817.
Bhatnagar, A., & Sillanpää, M. (2010). Utilisation of agro-industrial and municipal waste materials as potential adsorbents for water treatment—a review. Chemical Engineering Journal, 157(2), 277-296.