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Chemosphere. 2004 Feb;54(7):815-21.

Study on hydrogen production with hysteresis in UASB.

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Center for Environmental, Safety and Health Technology Development, Industrial Technology Research Institute, 321 Kuang Fu Road, S-2, Hsinchu City 300, Taiwan.


This paper uses a 10-l UASB (upflow anaerobic sludge blanket) bench-scale reactor to treat the esterification wastewater of a polyethylene terephthalate manufacturing plant. Two organic loading rates are used to evaluate the effect on H2 production of temperature gradually step-down and step-up in the range of 11-25 degrees C. Experimental results show that H2 production is positively related to temperature. H2 production increases with temperature at the higher organic loading rate (4.5 kg COD m(-3)d(-1)). However, the H2 produced does not go back to its original concentration but rather follows a hysteresis curve. This hysteresis also occurs in the corresponding concentrations of COD, acetate, propionate and butyrate. As in the H2 profiles, these parameter curves return clockwise during the temperature step-up. At the lower organic loading rate (2.2 kg COD m(-3)d(-1)), no obvious hysteresis is observed for H2 curve. The pattern of other parameters, except for the propionate, returns counterclockwise resulting in the hysteresis phenomena.

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