Tuesday, April 1, 2008 - 8:50 PM

Effects of Operational Conditions and Characteristics of Flocculation at Hydrogen Production by Using Immobilized Bed Bioreactor

Akira Sano, Yokohama National University and Shigeharu Tanisho, Yokohama National University.

A strain HN001 was shown to be effective in hydrogen production. In this study, the effects of operational conditions on hydrogen production were investigated. The characteristics of flocculation were figured out in case of continuous cultivation using supporter for immobilization. Diatomite, ceramic, activated carbon, plastic, synthetic fiber and mesh were used as a sample of selectable supporter for immobilization. A cylindrical vessel (2.0 L) made from acrylic plastic was used as a cultivation tank. A circulation method was adopted for agitation. Temperature and pH of the cultivation were kept constant at 43 °C and 6, respectively. Glucose concentration and agitation flow rate as operational conditions were changed and HRT was controlled constantly at 2.5 h. The agitation flow rate was an important factor of H2 production rate because of the gas separation of void in packed bed. The H2 production rate became higher along the increase of the flow rate. The maximum H2 production rate was 3.1 L-H2 h-1 (1.6 L-H2 h-1 L-culture-1) under the glucose concentration of 30 g L-1. Each supporter after cultivation for 1 week was dried and the weight of bacteria immobilizing on the supporter was calculated. Ceramic D, activated carbon E, synthetic fiber H and synthetic mesh I were expected to be effective supporters for immobilization of the strain HN001. The culture liquid of void in packed bed was isolated from the other part of culture liquid and the bacterial concentration in each culture liquid was measured separately to check the flocculation of void in packed bed. The bacterial concentration of void in packed bed was higher than that in culture liquid and the flocculation proceed in the packed bed. Synthetic fiber H was an effective supporter for immobilization at high bacterial concentration.

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