Biological H2 potential harvested from complex gelatinaceous wastewater via attached versus suspended growth culture anaerobes

- Suspended and attached growth exhibited different behavior for H2 production.
- Attached needs less volume than suspended growth to achieve similar removal efficacy.
- Net gain energy obtained from suspended growth is 4-folds higher than attached one.
- Unlike lipase, activities of amylase and protease are higher in attached growth.

The effect of cultural growth treating gelatinaceous wastewater on hydrogen fermentative was assessed using up-flow multi-stage anaerobic sponge reactor (UMASR) and anaerobic sequencing batch reactor (AnSBR). Both reactors were operated at five hydraulic retention times (HRTs). UMASR achieved the maximum COD removal efficiency of 60.2 ± 4.4% at HRT of 48 h. Moreover, UMASR exhibited superiority in the course of carbohydrates and proteins removal efficiencies' of 100 and 52.5 ± 2.4% due to high amylase and protease activities' of 4.1 ± 0.3 and 0.032 ± 0.002 U, respectively. Contrariwise, AnSBR assigned for the peak hydrogen production rate of 1.17 ± 0.14 L/L/day at HRT of 24-h. Lipase activity was quite high (0.307 ± 0.023 U) in AnSBR resulting in removal efficiency of 35.2 ± 2.1% for lipids. Stover-Kincannon model emphasized that UMASR required lesser volume than AnSBR to sustain the same substrate degradation efficacy. Nevertheless, the net gain energy harvested from AnSBR surpassed UMASR by 4.0-folds at HRT of 24-h.