An effective start-up of thermophilic UASB reactor by seeding mesophilically-grown granular sludge

• Published in: Water science and technology Vol. 36; no. 6-7; pp. 391 - 398
• Main Authors: Syutsubo, Kazuaki, Harada, Hideki, Ohashi, Akiyoshi, Suzuki, Hiroshi
• Format: Journal Article Conference Proceeding
• Language: English
• Published: London Elsevier Ltd 01.01.1997; IWA Publishing
• Subjects: Acetates; Acetic acid; alcohol distillery wastewater; Alcohols; Anaerobic digestion; Anaerobic processes; Bioreactors; Carboxylic acids; Chemical oxygen demand; Cultivation; Distilleries; Effluent treatment; Granulation; Hydrogen; methanogenic activity; Methanogens; Propionic acid; Reactors; Removal; seeding material; Sewage sludge; Sludge; start-up; Thermophilic anaerobic treatment; UASB process; Upflow anaerobic sludge blanket reactors; Wastewater; seeding material; alcohol distillery wastewater; Thermophilic anaerobic treatment; methanogenic activity; start-up; UASB process; granulation
• ISSN: 0273-1223; 1996-9732
• DOI: 10.1016/S0273-1223(97)00547-7

After seeded with mesophilically-grown (35°C) granular sludge, a laboratory-scale UASB reactor was thermophilically (55°C) operated over 8 months by feeding with an alcohol distillery wastewater. Use of mesophilically-grown granules as a seed material proved to be more advantageous for rapid and stable start-up of thermophilic UASB process, compared with the use of suspended-growth sludge taken from a thermophilic anaerobic digester. The reactor accommodated successfully a COD loading 30 kgCOD·m−3·d−1 , with a COD removal efficiency of 85%. However, during a period of 30 kgCOD·m−3·d−1 , propionate accumulated in the effluent up to 300–600 mgCOD·l−1. Thermophilic cultivation caused a drastic increase of methanogenic activities (55°C) of the retained sludge: 4.4 times for acetate, 4.6 times for propionate, and 3.5 times for hydrogen as large as those of the seed sludge. A considerably low value of propionate-fed methanogenic activity, i.e. only 1/5 of acetate-fed activity and only 1/23 of hydrogen-fed activity, suggested that the propionate degradation is subject to be a rate-limiting step in thermophilic anaerobic processes.