PRODUCTION OF HYDROGEN AND METHANE FROM FOOD PROCESSING WASTE IN INDUCED BED REACTORS: EXPERIMENT AND MODELING

Conly Hansen and Jianming Zhong

Dept. Utah State University, Logan, UT, 84322-8700, USA

Abstract

This study investigated effects of pH, temperature, hydraulic retention time (HRT), and organic loading rate (OLR) on hydrogen production from food processing waste (FPW) using dark fermentation in semi-continuous 60 L pilot induced bed reactors (IBR). Results show pH played a key role on hydrogen production with optimal pH range of 4.8-5.5. Digestion under thermophilic temperatures (60 °C) had advantages of gaining higher hydrogen yield and suppressing growth of methanogens. The optimal OLR was 32.9 g-chemical oxygen demand (COD)/l d at 3 d HRT. Under optimal conditions highest hydrogen yield was 71.7 ml/g COD_loaded with 44.6% COD removal. Two-stage digestions demonstrated more energy gain from methane and further COD removal. The overall gas production in two-stage digestion was 71.7 ml hydrogen and 61.0 ml methane g/DPW COD. The overall COD removal under optimal conditions was 88.2%. The Anaerobic Digestion Model No. 1 (ADM 1) was modified and implemented in software R to describe and correctly predict hydrogen production from FPW. Validation results show this model described reasonably well the dynamic behavior of hydrogen production in IBR. DNA-based studies to characterize IBR microbiology are underway and should facilitate efforts to refine and enhance reactor operations.