Using wastes to enhance bioremediation of oil-contaminated sites

The Microbiology Society is undertaking a project entitled A Sustainable Future as part of our 75th Anniversary, which aims to highlight the Sustainable Development Goals (SDGs) to our members and empower them to use their research to evidence and impact the goals. Earlier this year, we put a call out to our members to submit case studies in the following three areas: antimicrobial resistance, soil health and the circular economy.

This case study is written by Dr Angela Sherry, Vice Chancellor’s Senior Fellow at the Department of Applied Sciences, Northumbria University, UK, who is a member of the Microbiology Society, and Sola Olawuyi, PhD student at the School of Natural and Environmental Sciences, Newcastle University, UK. It focuses on the circular economy; an alternative to a traditional linear economy (make, use, dispose), in which we keep resources in use for as long as possible, extract the maximum value from them while in use, then recover and regenerate products and materials at the end of each service life.

What are the challenges that this research addresses?

Oil pollution is a worldwide problem and will continue to be so for the foreseeable future, even as we transition away from the use of fossil fuels. Despite extensive research in this area, current remediation technologies do not satisfactorily address the issue. Hydrocarbon-degrading micro-organisms are ubiquitous in oil-contaminated sites and use the oil compounds as sources of carbon and energy, consequently biodegrading the oil. However, relying on natural attenuation by indigenous micro-organisms to degrade the oil occurs over decadal timescales; therefore, processes to stimulate and enhance the biodegradation of crude oil in the environment are essential to bioremediation strategies.

Within the environment, the absence of nutrients is often a limitation for the growth and metabolism of micro-organisms. It has long been known that the addition of nutrients into oil-contaminated sites provides a successful strategy for the stimulated bioremediation of marine oil-spill clean-up operations, where slow-release fertilisers are applied to oil-contaminated beach sediments to stimulate hydrocarbon-degrading micro-organisms¹. Nitrogen and phosphorus have traditionally been considered the most important nutrients to limit the stimulation of crude oil biodegradation, but trace nutrients, especially essential trace metals, may also be important². 

The research, being undertaken at Newcastle University, aims to determine whether natural and anthropogenic wastes can be used to effectively supply trace nutrients to micro-organisms to enhance the biodegradation of hydrocarbons. Contributions to the circular economy include a cost-effective repurposing of existing waste streams, a reduction in environmental pollution due to enhanced bioremediation, land remediation, and the sequestration of carbon dioxide to mitigate against climate change, leading to a more sustainable future. The research addresses targets within the UN Sustainable Development goals 6 (clean water and sanitation), 12 (responsible consumption and production), 13 (climate action), 14 (life below water) and 15 (life on land)³.

What findings and solutions were provided by this research?

Wastes under investigation include dolerite, basalt, granite, incineration ash, steel slag, construction and demolition waste, olivine and dolomite. At the half-way stage through the project, a full suite of physicochemical and geochemical characterisation of the wastes has been determined to ensure waste additions would not have further deleterious effects if applied to environments that are already polluted by crude oil. Experimental microcosms have been prepared to investigate crude oil biodegradation in response to the addition of the wastes in agricultural soils and coastal sediments, to determine the effects of nutrient-stimulation in both terrestrial and marine systems. Carbon dioxide gas was monitored to assess if the mineralisation of the oil was stimulated by the addition of the wastes. The degradation of hydrocarbons will also be assessed using oil geochemistry, and microbial communities involved in the biodegradation of the oil will be determined with high-throughput DNA sequencing.

How can this research support the transition to a more sustainable future?

Determining if waste materials can provide key nutrients required to stimulate rates of oil bioremediation will serve to contribute to the circular economy and a more sustainable future by:

1) Enhancing the bioremediation of oil-contaminated sites, thereby reducing pollution in the environment (addressing goals 6, 14 and 15)  

2) Repurposing otherwise unused materials, that are considered wastes, and facilitate their removal from land and sources which can then be reused (addressing goals 12 and 15).

3) Sequestering carbon dioxide to mitigate against climate change. The use of mineral wastes has potential benefits in addition to the release of trace nutrients to stimulate the breakdown of hydrocarbons. The weathering of mineral wastes involves the leaching and transportation of calcium and magnesium ions into solution, which react naturally with dissolved carbon dioxide. The result is the sequestration of carbon dioxide from the atmosphere into the mineral fraction of soils, which could mitigate against global warming and climate change by reducing atmospheric CO₂ pollution (addressing goal 13).

What is the future for research and innovation in this area?

A sustainable, enhanced process to bioremediate hydrocarbons in oil-contaminated environments, using wastes to provide nutrients to stimulate the hydrocarbon-degrading microbiota.

References

¹Atlas RM, Bartha R. (1972). Biodegradation and mineralization of petroleum in

seawater: limitation by nitrogen and phosphorus. Biotechnology and Bioengineering 14, 309–318.

²Mejeha OK, Head IM, Sherry A, McCann CM, Leary P, Jones DM, Gray ND. (2019). Beyond N and P: The impact of Ni on crude oil biodegradation. Chemosphere 237:124545.

³United Nations Department of Economic and Social Affairs. (2015). Transforming our world: The 2030 Agenda for Sustainable Development. https://sdgs.un.org/2030agenda.

Project team (authors Sola Olawuyi & Angela Sherry):

Sola Olawuyi (PhD student, School of Natural and Environmental Sciences, Newcastle University)

Obioma Mejeha (Lecturer, Department of Microbiology, Federal University of Technology, Owerri, Nigeria)

Angela Sherry (Vice Chancellors Senior Research Fellow, Department of Applied Sciences, Northumbria University)

Neil Gray (Professor of Geomicrobiology, School of Natural and Environmental Sciences, Newcastle University)

Ian Head (Professor of Environmental Microbiology, School of Natural and Environmental Sciences, Newcastle University)

---