Polyurethane as an alternative support media to low-density polyethylene in fermentative-sulfidogenic reactors: Beneficial or indifferent?

• Published in: Journal of water process engineering Vol. 58; p. 104768
• Main Authors: Gil-Garcia, Carolina, Fuess, Lucas Tadeu, da Silva Rabelo, Camila Abreu Borges, Damianovic, Márcia Helena Rissato Zamarioli
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2024
• Subjects: 16S rRNA sequencing; AnSTBR; Sulfidogenic first stage; Support media selection; Two-stage anaerobic digestion; GC/FID; SRB; NaOH; ECEtOH; HRT; HS; AHS; ORR; HCl; VFA; OTU; SRR; OLR; Two-stage anaerobic digestion; IA; SLR; COD; AnSTBR; PBS; Support media selection; TDS; ZnSO4; 16S rRNA sequencing; H2S; GC/TCD; LUV; RA; CSTR; Na2SO4; PA; REC; Sulfidogenic first stage; VSS; ERCOD; ERSO4; SO42; UASB
• ISSN: 2214-7144; 2214-7144
• DOI: 10.1016/j.jwpe.2023.104768

Sporadically addressed in previous studies, the removal of sulfate during fermentation has been a matter of great interest in new applications of fixed-film two-stage biodigestion as the most efficient strategy to boost methane production from a low-sulfate fermented substrate. This study assessed the use of polyurethane (PU) as the support material in a thermophilic (55 °C) fermentative/sulfidogenic fixed-film reactor subjected to different operating conditions based on the variation of the sulfate loading rate (SLR = 8.0–4.0 kg-SO42− m−3 day−1), HRT (12.0–16.0 h) and liquid upflow velocity (3.42–7.90 m h−1). A maximum sulfate removal efficiency of only 46.8 % was achieved when applying SLR and HRT of 4.0 kg-SO42− m−3 day−1 and 16.0 h, respectively, reaching a total dissolved sulfide concentration of 275 mg L−1. This poor performance resulted from two factors: the interspaced arrangement of PU pieces and the use of ethanol as the only carbon source. While the first triggered excess biomass accumulation, the latter favored the establishment of a very restricted microbial community. Only some Clostridia-like bacterial classes, Proteobacteria, and other non-SRB bacteria belonging to phyla Synergistetes and Thermotogae were identified. Hence, under the studied conditions, using PU did not enhance sulfidogenesis in the fermentative reactor. [Display omitted] •Polyurethane assessed as support media in a fermentative-sulfidogenic biofilm reactor•Low sulfate removal efficiency (14.1–46.8 %) was observed•Using ethanol as the only carbon source metabolically restricted the reactor•Media arrangement triggered excess (non-beneficial) biomass accumulation•Sulfate reduction carried out by Desulfovibrio and likely by Coprothermobacter