Sulphur balance in anaerobic cultures of microorganisms in medium with phosphogypsum and sodium lactate

Biotransformation of phosphogypsum in two anaerobic cultures of mesophilic and thermophilic bacteria was investigated. In the both cultures an increase of sulphide ions was found, adequate to reduction of ca 50 % of sulphates in phosphogypsum. The mineral fraction of the post-reaction precipitates was equal to 43 and 35 % of the initial mass of phosphogypsum in the meso- and thermophilic cultures, respectively. It comprised, in addition to the residue of phosphogypsum, calcite (in the mesophilic cultures) or calcite and apatite (in the thermophilic cultures). In the both post-reaction precipitates, concentrations of lanthanides increased from 0.56 % in phosphogypsum substrate to 1.28 % in the mesophilic bacteria cultures, and to 1.47 % in the thermophilic ones.