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Low temperature removal of inorganic sulfur compounds from mining process waters
Author(s) -
Liljeqvist Maria,
Sundkvist JanEric,
Saleh Amang,
Dopson Mark
Publication year - 2011
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.23057
Subject(s) - tetrathionate , thiosulfate , sulfur , tailings , chemistry , sulfide , environmental chemistry , effluent , sulfate , sulfuric acid , oxidizing agent , thiobacillus , acidithiobacillus , acid mine drainage , gold cyanidation , claus process , polysulfide , inorganic chemistry , hydrogen sulfide , cyanide , environmental engineering , environmental science , acidithiobacillus ferrooxidans , organic chemistry , bioleaching , copper , electrode , electrolyte
Process water and effluents from mining operations treating sulfide rich ores often contain considerable concentrations of metastable inorganic sulfur compounds such as thiosulfate and tetrathionate. These species may cause environmental problems if released to downstream recipients due to oxidation to sulfuric acid catalyzed by acidophilic microorganisms. Molecular phylogenic analysis of the tailings pond and recipient streams identified psychrotolerant and mesophilic inorganic sulfur compound oxidizing microorganisms. This suggested year round thiosalt oxidation occurs. Mining process waters may also contain inhibiting substances such as thiocyanate from cyanidation plants. However, toxicity experiments suggested their expected concentrations would not inhibit thiosalt oxidation by Acidithiobacillus ferrivorans SS3. A mixed culture from a permanently cold (4–6°C) low pH environment was tested for thiosalt removal in a reactor design including a biogenerator and a main reactor containing a biofilm carrier. The biogenerator and main reactors were successively reduced in temperature to 5–6°C when 43.8% of the chemical oxidation demand was removed. However, it was found that the oxidation of thiosulfate was not fully completed to sulfate since low residual concentrations of tetrathionate and trithionate were found in the discharge. This study has demonstrated the potential of using biotechnological solutions to remove inorganic sulfur compounds at 6°C and thus, reduce the impact of mining on the environment. Biotechnol. Bioeng. 2011; 108:1251–1259. © 2011 Wiley Periodicals, Inc.