A review of the status of organic pollutants in geothermal waters

Abstract

Studies on organic pollutants in geothermal environments have received little attention; hence this review is necessary. The presence of trace organic pollutants such as benzene and xylenes has been reported as some of the main sources of pollution in geothermal systems. Previous studies using quantitative fluid inclusion gas analysis, Fischer–Tropsch Type (FTT) experiments and Gas chromatography-Mass spectrometry (GC-MS) have shown that there is a considerable presence of organic pollutants such as trace mono aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAHs), and emerging organic contaminants whose origin is both biogenic and abiogenic. Organic pollutants were initially not considered in geothermal development and utilization despite the fact that these toxic chemicals can precipitate severe ecological poisoning and potential risks to human health and aquatic life in a given geothermal environment, even at very low concentrations. The significant presence of benzene in various geothermal systems is of concern because it is a precursor for many aromatic compounds that are bio-accumulative and toxic to water regimes and the environment. Thermophilic and mesophilic bacteria, nonetheless, play a critical role during the biodegradation of organic pollutants in geothermal regimes. From the findings of this review, it is difficult to classify geothermal energy exploitation and utilization as an environmentally benign resource.