The National Conference for Postgraduate Research 2016, Universiti Malaysia Pahang 783 Influence of nano nickel oxide (NNO) particles on hydrogen production in dark fermentation of palm oil mill effluent Puranjan Mishra, Lakhveer Singh, Zularisam Ab Wahid * , Faculty of Engineering Technology Universiti Malaysia Pahang, Lebuhraya Tun Razak 26300 Kuantan, Pahang, Malaysia *e-mail: zularisam@ump.edu.my Abstract - Batch experiment with initial pH of 5.5, was conducted to produce hydrogen from palm oil mill effluent (POME). Nano nickel oxide (NNO) particles were supplemented (20-140 mg\l) to POME to enhance biohydrogen production. Clostridium species LS2 was used as inoculum. At initial hydrogen production rate was significantly increased from 2 to 15 ml H 2 /h with the increasing NNO particle concentration from 20 to 80 mg/l.. While the NNO concentration continued to increase from 80 to 140 mg/l, the hydrogen production rate gradually decreased. The maximum COD removal potential of 59 % was obtained in the presence of 80 mg/l of NNO after 96 h of dark fermentation. Addition of nano micronutrient to the production medium enhanced the hydrogen production rate and COD removal efficiency thus improved concurrent hydrogen production and pollution reduction from POME with activated sludge. Keywords: Biohydrogen; Nano nickel oxide particles; COD removal; Dark fermentation 1. INTRODUCTION Shortfall of fossil fuel makes it necessity to find out the alternative way of fuel. Hydrogen production via waste fermentation has significant approach due to its zero carbon emission at the point of use and a high energy yield of 142.35 kJ/g, which is 2.75 times than that of any other hydrocarbon fuel[1, 2]. [Ni–Fe] hydrogenases and the [Fe–Fe] hydrogenases are the enzymes which are able to catalyze reduction reactions inside the bacterium during hydrogen production. They content metal ions in their active sites [3].The [Ni–Fe] hydrogenases are widely distributed among bacteria, whereas the [Fe–Fe] hydrogenases are restricted to a few bacteria. Moreover, the [Ni–Fe] hydrogenases have a higher substrate affinity than the [Fe–Fe] hydrogenases [4]. Since nickel is a fundamental component making up the [Ni–Fe] hydrogenases, it may influence the fermentative hydrogen production by influencing the activity of [Ni–Fe] hydrogenases and thus may play an important role in fermentative hydrogen production. The potential of using palm oil mill effluent (POME) as a fermentation medium to produce hydrogen gas has been recently researched [5,6]. Study of nano particle functions is gaining impetus because nanoscience and nanotechnology encompass a wide range of fields, including chemistry, physics, materials engineering, biology, catalysis, medicine, and electronics. Small quantities of many metals, including copper, magnesium, sodium, potassium, calcium, and iron are essential for proper functioning of biological systems[7].Important parameters such as yield, efficiency, release rates, and cost have all seen benefits from the application of nano particles [8]. Considering the essentiality of nickel to fermentative hydrogen production, the objective of this study was to investigate the effect of Ni 2+ oxide nano particles ranging from 20 to 140 mg/l on fermentative hydrogen production by using culture of Clostridium sp. LS2 from palm oil mill effluent in batch test with the purpose of obtaining the appropriate concentration of nano nickel oxides.