Henning Prommer writes in The Conversation (23.11.16) about a new CSIRO report which suggests that the billions of litres of water extracted from coal seam gas exploration, when treated, can potentially be pumped back underground.
'Water produced when coal seam gas (CSG) is extracted from below ground can be safely re-injected hundreds of metres underground, according to new CSIRO research.
'Water is pumped out of coal seams to access the gas held within them. CSG in the Surat Basin, Australia, produces on average 70 gigalitres of water each year - a seventh of the water held in Sydney Harbour. What to do with this water is one of a number of concerns voiced by communities around CSG.
'Our research shows that injecting large volumes of treated CSG-produced water at suitable locations within the Surat Basin is unlikely to cause any harm to groundwater quality.
'However, to achieve this the water has to be treated adequately to eliminate the risk of polluting groundwater with arsenic – a generally immobile toxic element that occurs naturally in some of the rock formations being considered for re-injection.'