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-0) with various electron acceptors. In this study the distribution pattern of S-0 produced by C27 in denitrifying sulfide removal (DSR) process was explored. The SEM observation identified that the particle size of the biogenic S-0 was at micron level. Strikingly, a novel distribution pattern of S-0 was revealed that the produced S-0 was not directly secreted extracellularly, but be stored temporarily in the cell interior. Pyrolysis at 65 degrees C for 20 min were recommended prior to S-0 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-0 by C27. The highest S-0 production was obtained at S/N of 3 and anaerobic condition seemed to favor the S-0 production by C27. This study would provide a theoretical support for highly efficient sulfide removal as well as S-0 recovery in sulfide-laden wastewater treatment.