A study of the process control and hydrolytic characteristics in a thermophilic hydrogen fermentor fed with starch-rich kitchen waste by using molecular-biological methods and amylase assay

Starch rich kitchen waste was chosen as the feedstock in this study and a 3 L intermit tent continuous stirred tank reactor (I CSTR) was established Within 240 days the maximum average hydrogen production rate of 2 2 L H-2 L-1 day(-1) and the highest average hydrogen yield of 2 1 mmol H-2 g COD-1 were both observed in run 3 2 which was operated at an eight day hydraulic retention time (HRT) and 39 g COD L-1 day(-1) of organic loading rate According to the analyses of amylase and reducing sugar the maximum average amylase activity was about 11 U mL(-1) in run 1 but the maximum solid carbohydrate hydrolysis rate was about 45% in run 3 Some Michaealis Menton kinetic parameters such as K-M (17 g L-1) and the maximum activity (1 5 U mL(-1)) of the amylase were obtained The best amylase reacting temperature was 55 degrees C and the best reacting pH was 44 tested with acetate buffer Twenty seven operational taxonomic units (OTUs) were selected from this reactor by using a cloning method According to the data of terminal restricted fragment length polymorphism (T RFLP) and amylase assay, the OTUs that were related to Thermoanaerobacterium thermosaccharolyticum and Clostridium sp were in direct proportion to the amylase activity (C) 2010 Professor T Nejat Veziroglu Published by Elsevier Ltd All rights reserved