Characterisation of the Contaminants Generated from a Large-Scale Ex-Situ Underground Coal Gasification Study Using High
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Characterisation of the Contaminants Generated from a Large-Scale Ex-Situ Underground Coal Gasification Study Using High-Rank Coal from the South Wales Coalfield Sivachidambaram Sadasivam & Renato Zagorščak & Hywel Rhys Thomas & Krzysztof Kapusta & Krzysztof Stańczyk Received: 14 May 2020 / Accepted: 24 September 2020 / Published online: 5 October 2020 # The Author(s) 2020
Abstract This paper presents an analysis of contaminants generated from large-scale, laboratory-based, underground coal gasification (UCG) experiments using a high-rank coal from the South Wales Coalfield. The experiments were performed at atmospheric and elevated pressures (30 bar) by varying the oxidants’ composition. The experiments were designed to predict the amount of produced water and contaminants generated at each stage of the operating conditions. The mass balance of water supplied and produced in the experiments was accounted for. Chemical analyses of produced water, char and ash contents were performed to quantify the inorganic and organic chemical parameters. Most of the contaminant concentrations in the produced water from the 30-bar pressure experiment were lower than the concentrations generated from the atmospheric pressure experiment. The measured concentrations of the inorganic chemical species and the inorganic parameters of the coal seam water from the South Wales Coalfield were used in theoretical calculations to predict Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11270-020-04888-1) contains supplementary material, which is available to authorized users. S. Sadasivam (*) : R. Zagorščak : H. R. Thomas Geoenvironmental Research Centre (GRC), School of Engineering, Cardiff University, The Queen’s Buildings, The Parade, Cardiff CF24 3AA, UK e-mail: [email protected] K. Kapusta : K. Stańczyk Główny Instytut Górnictwa (Central Mining Institute), Plac Gwarków 1, 40-166 Katowice, Poland
the dominant equilibrium species concentrations in a hypothetical scenario of effluent contaminated groundwater. The biodegradation of organic contaminants such as phenol, benzene and sorbed fractions of inorganic contaminants from the produced water on iron oxide in the ash residue was predicted using existing biotransformation kinetics and surface complexation models, respectively. The biodegradation of phenol and benzene would be a slow process even at optimum conditions and the iron oxide left in the cavity can act as a sorbent for a few inorganic species. The evidence from the present study suggests future work towards (i) developing an appropriate water treatment process during gas cleaning, (ii) operational procedure (pressure and proportions of oxidant) and (iii) developing UCG-specific experimental prediction of contaminant transportation and transformation kinetics. Keywords High-rank coal . Underground coal gasification . High pressure . Produced water . Inorganic organic contaminants . Ash
1 Introduction Underground coal gasification (UCG) is a process through which gasification
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