In recent years the quantity of natural gas available has increased significantly due to shale gas production. However, shale gas extraction and processing produce large amounts of wastewater containing high concentrations of suspended solids, organics, chemicals, naturally occurring radioactive materials and dissolved inorganic materials (e.g. halides and heavy metals). Energy and/or material intensive treatment methods are currently utilised to recycle fracking wastewaters.
The use of catalysts for the removal of the organic fraction from fracking wastewaters offers a less energy and material intensive option compared to various conventional methods such as thermal distillation/mechanical vapour recompression, physical adsorption and biological treatment. Moreover, the production of chlorine and/or fine chemicals through catalysed process is possible and would allow valorising produced wastewaters as an additional advantage. However, it is paramount to evaluate carefully the sustainability of the proposed processes. As part of the evaluation, this study aims to assess the life cycle environmental impacts of different proposed catalysed processes to determine the most sustainable option(s) for shale gas wastewater treatment.
The results of this study will guide technology developers towards the choice of more sustainable raw materials, chemicals and processes to be used in different treatment processes. Furthermore, it is necessary to carefully evaluate the environmental risks related to the presence of considered contaminants in water to prioritise the treatment of the most hazardous compounds. Overall, combining life cycle assessment and environmental risk assessment will help in identifying the most sustainable options for wastewater treatment.
Marco Tomatis (Manchester)
Marco Tomatis, Laurence Stamford and Adisa Azapagic
Sustainable Industrial Systems, School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester, UK