Effects of Stressed Loading on Startup and Granulation in Upflow Anaerobic Sludge Blanket Reactors
Publication: Journal of Environmental Engineering
Volume 130, Issue 7
Abstract
The successful operation of an upflow anaerobic sludge blanket (UASB) process depends on the formation of settleable and active granular sludge. As the anaerobic bacteria are slow-growing microorganisms, a common problem encountered in UASB operation is the long startup period and the development of biogranules. In the present study, an unconventional approach to accelerate startup and granulation processes in UASB reactors has been developed by stressing the organic loading rate (OLR) without having to reach steady-state conditions. Three UASB reactors treating a synthetic feed with chemical oxygen demand (COD) of 2,500 mg/L, at a mesophilic temprature of 35°C were studied. One reactor (R1) served as a control, while the other two (R2 and R3) were operated at different stress levels upon reaching COD removal efficiency of 75 and 85%, respectively. Experimental results indicated that under stressed loading conditions, the startup, and granule development were accelerated by 45 and 33%, respectively, along with the formation of granules of superior characteristics without deteriorating loading capacity. The operating time to reach designated OLRs was also shortened by at least 30 days in the stressed reactors. The results presented indicate that the unconventional startup approach could offer a practical solution for the inherent long start-up in UASB systems with concomitant saving in time and cost.
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Information
Published In
Journal of Environmental Engineering
Volume 130 • Issue 7 • July 2004
Pages: 743 - 750
Copyright
Copyright © 2004 American Society of Civil Engineers.
History
Received: May 30, 2002
Accepted: Jun 10, 2003
Published online: Jun 15, 2004
Published in print: Jul 2004
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