title: Study on hydrogen production with hysteresis in UASB.
abstract: 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.
authors.affiliation: Center for Environmental, Safety and Health Technology Development, Industrial Technology Research Institute, 321 Kuang Fu Road, S-2, Hsinchu City 300, Taiwan. ghhuang@itri.org.tw
authors.forename: G H
authors.initials: GH
authors.lastname: Huang
authors.forename: S F
authors.initials: SF
authors.lastname: Hsu
authors.forename: T M
authors.initials: TM
authors.lastname: Liang
authors.forename: Y H
authors.initials: YH
authors.lastname: Huang
mesh_terms: D000085:Acetates; D000693:Anaerobiosis; D019149:Bioreactors; D002087:Butyrates; D006859:Hydrogen / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D010100:Oxygen / Q000737:chemistry; D011422:Propionates; D012722:Sewage / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D000085:Acetates; D002087:Butyrates; D007220:Industrial Waste; D011422:Propionates; D012722:Sewage; D006859:Hydrogen; D010100:Oxygen