A novel intra- and extracellular distribution pattern of elemental sulfur in Pseudomonas sp. C27-driven denitrifying sulfide removal process.

Pseudomonas sp. C27 can achieve the conversion of toxic sulfide to economical elemental sulfur (S) with various electron acceptors. In this study the distribution pattern of S produced by C27 in denitrifying sulfide removal (DSR) process was explored. The SEM observation identified that the particle size of the biogenic S was at micron level. Strikingly, a novel distribution pattern of S was revealed that the produced S was not directly secreted extracellularly, but be stored temporarily in the cell interior. Pyrolysis at 65 °C for 20 min were recommended prior to S recovery, which could maximize the separation of extracellular polymeric substances (EPS) from C27. Furthermore, the effects of N/S molar ratio, initial sulfide concentration, and micro-oxygen condition were investigated to improve the production of S by C27. The highest S production was obtained at S/N of 3 and anaerobic condition seemed to favor the S production by C27. This study would provide a theoretical support for highly efficient sulfide removal as well as S recovery in sulfide-laden wastewater treatment.