Batch and continuous fermentative production of hydrogen with anaerobic sludge entrapped in a composite polymeric matrix
Cell immobilization techniques were adopted to biohydrogen production using immobilized anaerobic sludge as the seed culture. Sucrose-based synthetic wastewater was converted to H2 using batch and continuous cultures. A novel composite polymeric material comprising polymethyl methacrylate (PMMA), collagen, and activated carbon was used to entrap biomass for H2 production. Using the PMMA immobilized cells, the favorable conditions for batch H2 fermentation were 35 °C, pH 6.0, and an 20 g COD l−1 of sucrose, giving a H2 production rate of 238 ml h−1 l−1 and a H2 yield of 2.25 mol H2 mol sucrose−1. Under these optimal conditions, continuous H2 fermentation was conducted at a hydraulic retention time (HRT) of 4–8 h, giving the best H2-producing rate of 1.8 l h−1 l−1 (over seven-fold of the best batch result) at a HRT of 6 h and a H2 yield of 2.0 mol H2 mol sucrose−1. The sucrose conversion was essentially over 90% in all runs. The biogas consisted of only H2 and CO2. The major soluble metabolites were butyric acid, acetic acid, and 2,3-butandiol, while a small amount of ethanol also detected. The PMMA-immobilized-cell system developed in this work seems to be a promising H2-producing process due to the high stability in continuous operations and the capability of achieving a competitively high H2 production rate under a relatively low organic loading rate.
Journal: Process Biochemistry - Volume 42, Issue 2, February 2007, Pages 279–284