Investigation of the pollution risk of residues from a laboratory-scale underground coal gasification of Malkara (Turkey) lignite
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The aim of this study was to examine the risk of heavy metal, ammonia and sulfate transition from underground coal gasification (UCG) chars and process water of Malkara lignite to the groundwater around the UCG cavity. The residues were collected during laboratory-scale underground coal gasification studies of Malkara lignite in ex situ gasification simulator. In order to compare gasification with combustion in terms of water pollution, ash samples were obtained by combustion of Malkara lignite. To determine the leaching behavior of the char and ash samples, two leaching tests (EPA TCLP and EN 12457-2 methods) were applied. The concentration of heavy metals in char, ash and process water samples was determined by ICP-OES. Additionally, ammonia and sulfate analyses were conducted for process water. Based on the results of this study, it has been found that the concentration of some elements, such as B, Sb and Al in char and ash eluates exceeded the maximum level of drinking water standards. However, there is no landfill concern about char samples according to EU Landfill Directive. A significant increase in B concentration was observed in ash samples. Considering B and some other elements combustion residues were identified with much higher water contamination ability, compared to gasification residues. Ammonia concentration was observed extremely high in process water of the gasification tests. UCG technique may be more environmentally applicable technology compared to combustion for Malkara lignite reserves. However, further detailed studies are necessary in the early stage of the UCG field test design and application.
KeywordsUnderground coal gasification Char Ash residue Metal elution Groundwater pollution
Acknowledgement is made to the TÜBİTAK (The Scientific and Technological Research Council of Turkey) Project No: 113M038 for their financial support. Authors also thank Dr. Cemile Yerlikaya and Esra Engin for their suggestions and technical supports in conducting this research.
- APHA 4500-SO4 (1992) Standard methods for the examination of water and wastewater. American Public Health Association, Washington, DC, USAGoogle Scholar
- Burton E et al (2004) Practices in underground coal gasification (performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.)Google Scholar
- Council of the European Union (2003) 2003/33/EC – Council decision establishing criteria and procedures for the acceptance of waste at landfills pursuant to article 16 of and Annex II to directive 1999/31/EC. Off J Eur Communities, pp 27–49Google Scholar
- Environment and Natural Resources (2004) Guideline for industrial waste discharges in the North Western Teritory, Canada, pp 1–15Google Scholar
- Pana C (2009) Review of underground coal gasification with reference to Alberta’s Potential, Energy Resources Conservation Board Report, 2009-10 AGS, CanadaGoogle Scholar
- Sury M, White M, Kirton J et al (2004) Review of environmental issues of underground coal gasification. Report No. COAL R273 DTI/Pub URN 04/1881, UKGoogle Scholar
- Verma RP, Mandal R, Chaulya SK et al (2014) Contamination of groundwater due to underground coal gasification. Int J Water Resour Environ Eng 6:303–311Google Scholar