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Evaluation of UASB reactor performance during start-up operation using synthetic mixed-acid waste

Vadlani, P.V., Ramachandran, K.B.
Bioresource technology 2008 v.99 no.17 pp. 8231-8236
biomass, chemical oxygen demand, gases, seeds, sludge, upflow anaerobic sludge blanket reactor, volatile fatty acids, waste treatment
A start-up experiment was performed in a laboratory-scale, upflow anaerobic sludge blanket (UASB) reactor using seed sludge from a domestic waste treatment plant at 3.8-33.3gCODl⁻¹ day⁻¹ loading rates. Analysis over the height of the reactor with time showed that the VSS in the reactor was initially differentiated into active and non-active biomass at increasing gas production and upflow velocities, and specific update rates of the volatile fatty acids (VFA) components were pronounced at the bottom 10% of the reactor. During start-up, specific methanogenic activity and chemical oxygen demand (COD) uptake rate increased from 0.075 to 0.75gCOD-CH₄ (gVSS)⁻¹ day⁻¹ and from 0.08 to 0.875gCOD removed (gVSS)⁻¹ day⁻¹, respectively. When seed sludge from a distillery waste treatment plant was used, improved performance due to a predominance of active biomass was evident when the loading rate was increased from 9.4 to 28.7gCODl⁻¹ day⁻¹. The proposed start-up evaluation is an effective tool to successfully monitor performance of UASB reactors.