UASB process consistently removed 84% of COD in wastewater with hydrolyzed proteins for loading rates up to 32 g-COD/L/day, corresponding to a food-to-microorganisms ratio of 0.81 g-COD/g-VSS/day, at 37°C and a hydraulic retention time of 9 hours. Of all the COD in the wastewater, about 74% was converted to methane, 16% was unhydrolyzed proteins which remained refractory to degradation, and 10% converted to biomass. The average sludge yield was 0.079 g-VSS/g-COD. There was no noticeable foaming and sludge flotation. The maximum specific methane production rate in the reactor was 0.60 g-methane-COD/g-VSS/day, which was comparable to the specific methanogenic activity (SMA) of 0.59 g-methane-COD/g-VSS/day observed by the serum vial test using hydrolyzed proteins as substrate. The SMA using acetate as substrate was 0.89 g-methane-COD/g-VSS/day, higher than those (0.39–0.59 g-methane-COD/g-VSS/day) using formate, propionate and butyrate, individually, as substrate. The granules did not have a layered structure nor a predominant type of bacteria. Instead, it had a densely packed structure with interwined bacteria of diverse morphologies with scattered microcolonies of Methanothrix, Methanosarcina, and justapositioned syntrophic associations.
Performance and granule characteristics of UASB process treating wastewater with hydrolyzed proteins
H. H. P. Fang, H. K. Chui, Y. Y. Li, T. Chen; Performance and granule characteristics of UASB process treating wastewater with hydrolyzed proteins. Water Sci Technol 1 October 1994; 30 (8): 55–63. doi: https://doi.org/10.2166/wst.1994.0381
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