Enhancing biohydrogen production from chemical wastewater treatment in anaerobic sequencing batch biofilm reactor (AnSBBR) by bioaugmenting with selectively enriched kanamycin resistant anaerobic mixed consortia

The basic aim of this study was to investigate the feasibility of bioaugmentation strategy in the process of enhancing biohydrogen (H-2) production from chemical wastewater treatment (organic loading rate (OLR)-6.3 kg COD/m(3)-day) in anaerobic sequencing batch biofilm reactor (AnSBBR) operated at room temperature (28 +/- 2 degrees C) under acidophilic microenvironment (pH 6) with a total cycle period of 24 h. Parent augmented inoculum (kanamycin resistant) was acquired from an operating upflow anaerobic sludge blanket (UASB) reactor treating chemical wastewater and subjected to selective enrichment by applying repetitive/cyclic pre-treatment methods [altering between heat-shock treatment (100 degrees C; 2h) and acid treatment (pH 3; 24h)] to eliminate non-spore forming bacteria and to inhibit the growth of methanogenic bacteria (NIB). Experimental data revealed the positive influence of bioaugmentation strategy on the overall H-2 production. Specific H-2 production almost doubled after augmentation from 0.297 to 0.483 mol H-2/kg CODR-day. Chemical wastewater acted as primary carbon source in the metabolic reactions involving molecular H-2 generation leading to substrate degradation. The augmented culture persisted in the system till the termination of the experiments. The survival and retention of the augmented inoculum and its positive effect on process enhancement may be attributed to the adopted reactor configuration and operating conditions. Scanning electron microscope (SEM) images documented the selective enrichment of morphologically similar group of bacteria capable of producing H-2 under acidophilic conditions in anaerobic microenvironment. This depicted work corroborated successful application of bioaugmentation strategy to improve H-2 production rate from anaerobic chemical wastewater treatment. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.