Operation performance of up-flow anaerobic sludge blanket (UASB) bioreactor for biohydrogen production by self-granulated sludge using pre-treated palm oil mill effluent (POME) as carbon source

• Published in: Renewable energy Vol. 134; pp. 1262 - 1272
• Main Authors: Mahmod, Safa Senan, Azahar, Azratul Madihah, Tan, Jian Ping, Jahim, Jamaliah Md, Abdul, Peer Mohamed, Mastar, Mohd Shahbudin, Anuar, Nurina, Mohammed Yunus, Mohammed Faisal, Asis, Ahmad Jaril, Wu, Shu-Yii
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2019
• Subjects: acetic acid; bacteria; Biohydrogen; biomass; butyric acid; byproducts; carbon; Clostridium; digestion; energy-dispersive X-ray analysis; Fourier transform infrared spectroscopy; granules; H2-producing granules; Hydraulic retention time; hydrogen production; hydrolysates; hydrolysis; industrial wastewater; mixed culture; nitric acid; oil mill effluents; Palm oil mill effluent; renewable energy sources; scanning electron microscopy; sludge; solubility; sugar content; UASB; upflow anaerobic sludge blanket reactor; Palm oil mill effluent; Hydraulic retention time; Biohydrogen; UASB; H2-producing granules
• ISSN: 0960-1481; 1879-0682
• DOI: 10.1016/j.renene.2018.09.062

Palm oil mill effluent (POME), an agro-industrial wastewater with high solids content, was subject to hydrolysis by 1% (w/v) nitric acid in order to increase its solubility and the fermentable sugar content from its cellulosic component. POME hydrolysate was then evaluated in an up-flow anaerobic sludge blanket (UASB) bioreactor for the production of biohydrogen gas via mixed culture under thermophilic conditions. The bioreactor was fed with pre-treated POME under varied hydraulic retention time (HRT) between 48 and 3 h at constant cycle length of 24 h to test the productivity of H2 and the stability of UASB; no washout of biomass occurred at any cycle and the system managed to recover its H2 production rate (HPR) after initial fluctuations. In this study, H2-producing granules (HPGs) were formed shortly after the start-up period, and were analysed by FESEM, FTIR, SEM-EDX, and their extracellular polymeric substances (EPS) content. The maximum HY and HPR achieved were 2.45 mol-H2/mol-sugar and 11.75 LH2/LPOME d−1, respectively, at HRT 6 h. Acetic acid was found to be the major by-product at all HRTs, followed by butyric acid, while Clostridium spp. was found to be the most dominant H2-producing bacteria in the system. Results suggest that UASB has a good potential for stable H2 production with high POME digestion rate. [Display omitted] •Raw POME was pre-treated using dilute nitric acid.•H2-producing granules from POME were produced in UASB.•Optimum biohydrogen yield achieved was 2.45 molH2/molsugar.•Bacterial community in H2 producing sludge was dominated by Clostridium spp.