Abstract

Remediation of contaminated land needs to be carried out using methods that are both cost effective and minimise environmental pollution. However, the remediation option currently chosen by practitioners is often based upon limited economic information with the true environmental costs not being considered. This can result in the least sustainable option being chosen.
This study has developed a methodology to evaluate the sustainability, in terms of economic and environmental costs, for a range of treatments available for the remediation of diesel contaminated land, including bioremediation (with and without the addition of brewery spent grain), disposal to landfill and thermal treatment.
Initial laboratory investigations indicated that the use of brewery spent grain decreased the time taken for the clean-up of soil contaminated with diesel, suggesting that bioremediation augmented by the addition of this organic material was a viable option. A costing model was then developed that included all of the costs associated with the remediation options chosen. This included both direct and indirect costs. The results show that considering the indirect costs of remediation such as costs associated with delayed development the land, make bioremediation in this study an economically feasible option.
Finally environmental costs were considered with a focus on the release of carbon dioxide a known greenhouse gas. Respirometry was used to determine the volume of carbon dioxide released during the bioremediation process. This information was then combined with data collected from a range of other sources and the impact of the chosen remediation options on atmospheric greenhouse gas release was evaluated. Other environmental impacts were also determined including land and water pollution. The results indicate that bioremediation with brewery spent grain has one of the lowest environmental costs and showed that emission from pollutants such as NOx, PM1.0, PM2.5, NH3 and SO2 could contribute to the limit values in the area covered by remediation work.
The model developed in this study has indicated that the use of bioremediation with and without the use of brewery spent grain is a sustainable remediation option providing both direct and indirect economic costs are included. The results have indicated that, the strategy of using brewery spent grain to augment bioremediation
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process promotes the re-use of by-product material, reduces waste and conserve resources. There is a need for the remediation industry to adopt similar models in order that decisions made, as to the remediation option chosen, are based upon accurate costings of their sustainability.