Biogenic sulfur as an effective source for sulfidogenesis via sulfur disproportionation (S0Disp)

Abstract

Sulfidogensis via element sulfur disproportionation (S0Disp) has been recently suggested to be a cost-effective and low carbon footprint process to produce sulfide for wastewater treatment such as denitrification and the removal of heavy metals. However, studies on this process are limited in using the industrial grade chemical sulfur (Chem-S0). In this study, biogenic sulfur (Bio-S0), a solid waste produced from biogas bio-desulfurization, was investigated for the first time in the S0Disp process with the performance compared to the Chem-S0 with identical size. The results showed that the S0Disp process driven by Bio-S0 was initiated more rapidly than that by the Chem-S0 (8 d vs 13 d) and performed a 1.2-fold higher sulfide production rate in the steady phase. A series of characterizations were conducted to elucidate the difference between using these two types of S0 in disproportionation. The faster initiation of Bio-S0 sets was suggested to correlate its hydrophilic properties, while the higher sulfide production rate was likely due to its higher reactivity as indicated by the lower crystallinity and the presence of organic polysulfane with lower dissociation energy for the S-S bond. Additional tests demonstrated that the Bio-S0 could be more readily attacked by the sulfide to produce polysulfide, a putative rate-limiting step of S0 taken by bacteria in the S0Disp process. Moreover, the sulfur-disproportionating bacteria were found to be enriched more in the Bio-S0 set, which might also contribute to the higher sulfide production rate. This study extended the knowledge of Bio-S0 in good bioavailability and offered new opportunities for reusing this solid waste.