Organic sulphur alterations in biodesulphurized low rank coals

► Coal biodesulphurization approach for organic/inorganic sulphur removal is applied. ► Prior to biodesulphurization processing, samples are chemically treated. ► The used microorganisms are “P. chrysosporium” and “S. solfataricus”. ► Extra maximal total and organic sulphur decreases of ∼24% are achieved. ► TPR-MS techniques are used for sulphur alteration assessment. Two Bulgarian high sulphur coals, i.e. subbutiminious (Pirin) and lignite (Maritza East), and one Turkish lignite (Cayirhan-Beypazari) are biodesulphurized on laboratory scale. Prior to biotreatments coal samples are chemically treated to be demineralized and depyritized. Due to chemical treatments total sulphur desulphurization in the range of 25.3–54.2% is achieved. Inorganic sulphur (pyritic and sulphatic) is mainly attacked. Pyritic sulphur desulphurization varies in the range of 59.6–77.4%. The white rot fungi “Phanerochaeta chrysosporium” –ME446 and the thermophilic and acidophilic archae “Sulfolobus solfataricus” –ATCC 35091 are the microorganisms applied in the biodesulphurization processes. Better biodesulphurization is attained for coal samples treated with “P. chrysosporium”. Maximum effect of biodesulphurization due to further total sulphur decrease (ΔSt) of 24.2% and further organic sulphur decrease (ΔSo) of 23.8% is registered after fungi biotreatments on deminerilized and depyritized coals. By “S. solfataricus” maximum further ΔSt and ΔSo biodesulphurization effects of 16.9% and 18.3%, respectively, are determined. AP-TPR device coupled with different detection systems (MS and TD-GC/MS) gives us opportunity to track organic sulphur alterations as a result of the applied biotreatments. By AP-TPR “off-line” TD-GC/MS an improved organic sulphur information is obtained due to specific sulphur sorbent application. A broad range of sulphur-containing organic compounds as well as SO2, COS and CS2 are identified and quantitatively interpreted.