Arab J Sci Eng (2016) 41:2563–2571 DOI 10.1007/s13369-016-2035-4 RESEARCH ARTICLE - CHEMICAL ENGINEERING Continuous anaerobic hydrogen and methane production using water hyacinth feedstock Chyi-How Lay 1,2,3 · Biswarup Sen 4 · Chin-Chao Chen 5 · Chiu-Yue Lin 1,2,5 Received: 3 September 2015 / Accepted: 18 January 2016 / Published online: 4 February 2016 © King Fahd University of Petroleum & Minerals 2016 Abstract The water hyacinth, Eichhornia crassipes, impacts the environment in a number of ways. This study develops a continuous cultivation strategy and investigates the effect of these strategies for hydrogen production in anaer- obic sequencing batch reactor (ASBR) and intermittent-cont- inuous stirred tank reactor (I-CSTR) systems using the water hyacinth as feedstock. Glucose (10 g/L) was used as the feed- stock to start-up the fermentor using pig slurry seed in a batch model. ASBR with increasing water hyacinth con- centration was used as the start-up strategy for hydrogen production. However, the hydrogen performance decreased with increasing water hyacinth concentration. Finally, the metabolic pathway shifted to methane production with no hydrogen. A strategy for controlling the substrate and reac- tion pH and shortening the hydraulic retention time (HRT) in I-CSTR was used to enhance the hydrogen production. Low hydrogen production performance was achieved with a hydrogen production rate of 1.1 with 82.4 mL/L-d methane B Chyi-How Lay chlay@fcu.edu.tw 1 Master Program of Green Energy Science and Technology, Feng Chia University, Taichung 407, Taiwan 2 Green Energy Development Center, Feng Chia University, Taichung 407, Taiwan 3 General Education Center, Feng Chia University, Taichung 407, Taiwan 4 Amity Institute of Biotechnology, Amity University Haryana, Gurgaon 122413, India 5 Environmental Resources Laboratory, Department of Landscape Architecture, Chung Chou University of Science and Technology, Changhwa 510, Taiwan 6 Department of Environmental Engineering and Science, Feng Chia University, Taichung 407, Taiwan production rate resulting from the I-CSTR operated using pH 4.0 feedstock and HRT 2 days. Keywords Anaerobic fermentation · Hydrogen and methane production · Water hyacinth · Operation strategy · Continuous system 1 Introduction Humanity has depended upon petroleum-based energy for several decades. Using petroleum causes the greenhouse effect. The Fukushima Daiichi nuclear disaster has induced people to consider searching for an alternative safe renewable energy source. Biomass energy has recently received more attention. A biomass resource from agricultural practices that produce 1.34 billion tons of product annually could be equiv- alent to more than 600 GW of continuous power for energy production without affecting food production [1]. Dark fer- mentation technology for biogas production would be the best candidate for practical application with the advantages of higher production rate and low-value biomass utilization. The water hyacinth, Eichhornia crassipes (E. crassipes), impacts the environment in a number of ways. The water hyacinth (WH) has high annual production yield (39.5 ton/ha-year) compared with other bioenergy plants [2]. It should be a good candidate as feedstock for bioenergy production. However, high efficiency of fermentative biogas production requires inoculum type, pre-treatment, substrate nature and compo- sition optimization, pH and temperature to scale-up in a continuous system [3]. Lin and Hung [4] reported that an enrichment process cultivating collected cow dung sludge in a thermophilic environment for a few days could effectively elevate the seed culture’s bioactivity. The results indicated that using α-cellulose and saccharification products (glucose 123