Potential of Biological Sulphur Recovery Under Haloalkaline Conditions

Tutkimustuotos: VäitöskirjaCollection of Articles

Abstrakti

Process industries, such as pulp and paper (P&P) and petrochemical, generate concentrated sulphurous process streams and wastewaters. The process streams, which are saline and alkaline (haloalkaline), require careful management as they potentially increase operational costs, related to chemical balancing and corrosion. Sulphur recovery by haloalkaliphilic sulphur oxidizing bacteria (SOB) instead of physicochemical methods would be a cost-efficient approach as it works at ambient pressure and temperature and produces separable elemental sulphur (S0). However, the wastewaters of organic raw-material processing industries can contain organic compounds that may harm chemolithoautotrophic SOB.

The aim of this work was to study the biological S0 recovery potential by chemolithoautotrophic SOB from haloalkaline sulphurous solutions for possible use in industrial process streams and wastewaters. Therefore, the kinetics of thiosulphate (S2O32-) biotransformation and growth of model haloalkaliphilic SOB (Thioalkalivibrio versutus and T. denitrificans) were delineated. Also, the S0 recovery by T. denitrificans under anoxic conditions was investigated. Third, the potential of continuous bioprocess with increasing S2O32- loading rates was studied in a T. versutus amended fluidized bed bioreactor (FBBR). Finally, the effects of organic compounds and P&P wastewaters on S2O32- biotransformation were delineated.

The kinetic studies showed high-rate S2O32- biotransformation by T. versutus (qm=0.083 h-1) and somewhat lower by T. denitrificans (qm=0.024 h-1) at high initial substrate concentrations under aerobic conditions. S0 was formed by both bacteria in the aerobic batch assays whilst it was not formed by denitrification by T. denitrificans. In the FBBR, 100% S2O32- removal efficiency and 27±2% S0 yield were achieved at loading rates of 19 g S/L/d and 22 g S/L/d, respectively. The non-aseptic FBBR system was suitable to maintain the pure culture but was not suitable for S0 settling. T. versutus showed high tolerance towards P&P mill wastewaters (primary filtrate of bleaching, composite wastewater) and the constituents studied in this work. Yeast extract (2.5-5 g/L) enhanced biotransformation and growth.

This work demonstrates efficient S2O32- biotransformation from synthetic solutions (pH 10, 14-26 g/L Na+) and P&P wastewaters under aerobic conditions. The outcomes of this thesis can be used for future bioprocess development.
AlkuperäiskieliEnglanti
JulkaisupaikkaTampere
ISBN (elektroninen) 978-952-03-2657-9
TilaJulkaistu - 2022
OKM-julkaisutyyppiG5 Artikkeliväitöskirja

Julkaisusarja

NimiTampere University Dissertations - Tampereen yliopiston väitöskirjat
Vuosikerta708
ISSN (painettu)2489-9860
ISSN (elektroninen)2490-0028

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