Enhanced treatment of Fischer-Tropsch (F-T) wastewater by novel anaerobic biofilm system with scrap zero valent iron (SZVI) assisted

- The novelty UAFB with SZVI was applied to F-T wastewater treatment.
- Modified Stover Kincannon kinetic model suitable to F-T wastewater treatment.
- Fe2+ leaching could increase EPS content to promote cells aggregation.
- SZVI corrosion could help to enrichment of H2-utilizing methanogens.
- SZVI corrosion enhance EET mechanism within syntrophic methanogenic consortia.

The scrap zero valent iron (SZVI) was applied in up-flow anaerobic fixed bedt (test group) to investigate the treatment for Fischer-Tropsch (F-T) wastewater, while the UAFBc (control group) was operated in parallel. The SZVI corrosion could buffer acidity of raw F-T wastewater and offer UAFBt a more reductive micro-environment for the enrichment of methanogens, and the chemical oxygen demand (COD) removal efficiency and methane production for UAFBt were always 11.2% and 0.42 L/L d higher than those of UAFBc in every operational stage. Additionally, with the assistance of SZVI, the coenzyme F420 and F430 concentration in UAFBt were found to be averagely 6.13 μmoL/g VSS and 11.49 μmoL Ni/g VSS, which were both higher than those of in UAFBc (2.91 μmoL/g VSS and 9.93 μmoL Ni/g VSS). The high-through put 16S rRNA gene pyrosequencing in our study further confirmed that the percentage of predominant H2-utilizing methanogens (Methanospirillum, Methanobacterium, Methanosphaerula and Methanolinea) were up to 30.31% of total archaeal sequences with SZVI involved, enhancing interspecies H2 transfer mechanism from organic acids oxidizers to syntrophic methanogensis, and taking beneficial to decompose propionic acid and butyric acid into acetic acid, finally contributing to completely methane production.

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