The Weisener Lab
biogeochemistry, environmental microbiology, geochemistry, and sediment dynamics
Aquatic Nutrient Dynamics in Windsor-Essex
**Stay tuned for details about some of our latest work in the Windsor-Essex Region, researching how nutrients pass through our ecosystems, their source/sink characteristics, and how they interact with particulate matter**
Remediation of AMD with mussel shell bioreactors
Acid mine drainage (AMD) occurs when uneconomical waste rock containing iron sulphides are exposed to the atmosphere, water, and microorganisms. This acidic water, if left untreated can damage ecosystems as it is acidic and contains high concentrations of dissolved metals and sulphate. A novel bioreactor technology, currently being studied by CRL Energy in New Zealand, is using waste mussel shells – a cheap alternative to conventional treatments. This novel treatment medium has a high neutralizing capacity, containing enough organic matter in the form of chitin (5-12wt%) to promote the growth of sulfur reducing bacteria (SRB). Mussel shells can therefore act as the sole component of the bioreactor. The mussel shell bioreactor (MSB) is currently treating an AMD seep at the Stockton coal mine on the west coast of the South Island, an area with a history of coal mining and AMD impacted freshwater streams. The coal mine is located on the Brunner Coal Measures with a lithology of coal and marine mudstones containing up to 5 wt% pyrite, with lesser carbonates providing little opportunity for natural neutralization of AMD waters (Weisener & Weber 2010; Pope et al. 2010). The MSB removes ~99% of all metals and raises the pH from 3.2-3.5, to 7.6-8.3, and is estimated to be 15 times more cost effective than traditional methods of remediation for both installation and maintenance (DiLoreto et al. 2016). Ongoing research is focused on addressing the functionality of the system, and improving on the hydro-geologic design.
Microbial function in hydrocarbon-rich freshwater sediments
Negative anthropogenic influences on our freshwater ecosystems are increasing, as natural resources are exploited for our growing global population, resulting in increased contaminant loads to these fragile habitats. The expansions and proposals for new cross-continental oil and gas pipelines requires a need for a comprehensive understanding of how freshwater microbial populations function in hydrocarbon-rich environments. These baseline characterizations can provide insight into proposed bioremediation strategies crucial in cleaning up contaminated spill sites. Recent catastrophes and the increasing likelihood for pipeline fractures in the future suggest that this research is more pressing than ever. This study was conducted to reveal comparisons of in-situ microbial gene expression within freshwater hydrocarbon-rich reference sites cutting through the McMurray formation – the geologic strata constituting the oil sands. This is the first study to reveal metatranscriptomic comparisons in these freshwater ecosystems. Results confirm previously reported taxonomic variation, but now provide insight into the in-situ gene expression within these sites. Energy metabolism and hydrocarbon degradation genes are characterized, with emphasis on nitrogen, sulfur and methane processes, including transcripts relating to the observed expression of anaerobic methane oxidation. Expression of alkane monooxygenase (alkB) correlating to PAH concentrations at each site suggest it’s effectiveness as a bioindicator gene in freshwater environments. This information provides better linkages between natural and contaminated landscapes, closing knowledge gaps for optimizing not only oil sands mine reclamation but also understanding the biogeochemistry of other freshwater sites at risk of hydrocarbon contamination in the future.
Novel detoxification treatment for oil sands tailings: validating reclamation strategies
The Athabasca Oil Sands of Northern Alberta, Canada is one of the largest bitumen reserves in the world, producing millions of barrels of oil per day. Given proximity of the surface, open-pit mining is a primary method of extracting bitumen from the ground, producing millions of liters of waste materials consisting of water, sand, clay and residual bitumen. These waste materials are quite toxic, given their relatively high hydrocarbon and salt content (among other more complex organics). Given the repetitive recycling of these waters to reduce freshwater consumption, contaminants become even more concentrated, requiring methods for detoxification and promote remediation down the road. During laboratory experimentation to study both biotic and abiotic factors controlling the evolution of tailings pond sediments, it was discovered that the commonly used gamma irradiation treatment (used for sterilization in the food industry for example) reduced the concentration of a certain organic compound by up to 96%. A patent was filed for by Dr. Weisener and his colleague Dr. Ciborowski, and subsequent work has sought to validate this detoxification treatment both in the laboratory and in larger scale field experiments. Research to date supports initial findings in that this treatment appears to speed up the process of remediation in the early stages of pond evolution. Our studies have shown that the microbial consortia responsible for biodegradation and metabolism in complex environments appear to be stimulated and geochemical analyses support these findings.
Investigating biofilm structure and function associated with point source water treatment
The Canadian government has increased the focus on regulating discharge of wastewater to the environment to avoid the release of excessive nutrient loads to water ways which can lead to the eutrophication of watersheds. The advent of new regulations many municipalities require substantial upgrades. Traditional wastewater treatment technologies are in some cases cost prohibitive. Bishop Water Technologies (BWT) provides an ecofriendly and cost-effective technology for treating Canadian wastewater (municipal and industrial) while removing nutrients to rivers and lakes. The BioCord technology relies on the formation of Biofilm, which is a natural aggregation of a complex community of microorganisms growing on a solid substrate. BioCord is a man-made polymer substrate suitable for biofilm growth (Yuan et al. 2012). The cord is covered with rings of thread, both rings and cord are made of different polymers. The premise is that BioCord provides more surface area for biofilm to attach and develop, mimicking underwater plants; the increased density of the biofim in principle has a direct relationship to the rate and efficiency of wastewater treatment. The substrates encourage the microbial process (Bacteria and Archaea) such as Methanogens, denitrification, phosphate removal (complexation) and/or sulphate reduction etc. The current challenge to developing this technology lies in a detailed understanding of the developing microbial biofilm associated with these BioCord substrates. In fact this technology still remains a black box from the perspective of optimum growth and treatment conditions under full scale implementation practice. Depending on the environment, different microbes will accumulate some nutrients better than others and in turn may promote or out compete the process dependent microbes (e.g. denitrifiers). We are currently using metagenomics and metatranscriptomics to identify and quantify the microbial species populating the different BioCord materials.
Project Photos
