An assessment of duckweed as a potential lignocellulosic feedstock for biogas production Dipti Yadav a, 1 , Lepakshi Barbora a, 1 , Deep Bora a , Sudip Mitra b , Latha Rangan a, c, * , Pinakeswar Mahanta a, d, ** a Center for Energy, Indian Institute of Technology Guwahati, Assam, 781039, India b Department of Environmental Science, Tezpur University, Napaam, Sonitpur, Assam, 784028, India c Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam, 781039, India d Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Assam, 781039, India article info Article history: Received 11 July 2016 Received in revised form 7 September 2016 Accepted 7 September 2016 Available online xxx Keywords: Biogas Duckweed Feedstock Lignin Volatile matter abstract Due to the complicated structure of lignocellulosic plant cell wall, their utilization for biogas production via anaerobic digestion has not been widely adopted. Alternative to this is to use aquatic plant materials as feedstock for biogas production. In this context, duckweed, an aquatic plant may prove to be a promising new energy source for bioenergy as well efficient CO 2 sequestration. This study entails a detailed characterization of duckweed to evaluate their potential as an alternate feedstock to cattle dung for biogas production. The duckweed was characterized for volatile matter, moisture content, ash content and carbon, hydrogen, and nitrogen (CHN) content. Property analysis of duckweed was also done by Fourier transform spectroscopy and thermogravimetric analysis. The volatile matter of duckweed was found to be 84.24± 0.2% with a lignin content of 12.2%, which is very encouraging for biogas production. Co-digestion of duckweed (DW) with cattle dung (CD) in varying ratios (DW:CD ¼ 90:10, 75:25, and 50:50 respectively) in batch type anaerobic digesters was performed at 37  C temperature for 55 days. The cumulative biogas production for CD (100%), DW/CD (90:10), (75:25) and (50:50) was found to be 11,620, 305, 11,695, and 12,070 mL, respectively, which indicated that duckweed can be a potential lignocellulosic feedstock when co-digested with cattle dung at an optimum ratio of 1:1. Methane content of the biogas from co-digested feedstock is comparable to the biogas from cattle dung alone. © 2016 Elsevier Ltd. All rights reserved. 1. Introduction Worldwide the consumption of renewable energy is on the rise. Concerns for energy security, efforts to mitigate the environmental impact of conventional fuels, and improvements in living standards and renewable technologies are the ingredients of sustainable en- ergy usage (Edenhofer et al., 2012). In this context, bioenergy is recognized as a potential player, which can lead a central role in promoting renewable alternatives. According to recent report by Ren21, Renewables 2015 Global Status Report (2015), the total primary energy demand from biomass in 2014 was approximately 16,250 Wh (58.5EJ). Various bioenergy production technologies, such as bioethanol, biodiesel, biomethane, etc., that use biomass as a substrate are receiving worldwide attention. As a sustainable energy source, biogas is one of the prospective alternatives iden- tified so far which is economically feasible, as it has the lowest financial input of output energy, unlimited in potential and eco- friendly in nature. Furthermore, from a socio-economic point of view, biomass waste can serve as feedstock for biogas production and hence significantly reduces the cost (Jain et al., 2015). Biogas can be readily converted to electrical and thermal energy via a co- generator, typically for onsite consumption (Wickham et al., 2016). It can be produced from different types of organic materials, such as industrial wastewater, food waste, sewage sludge and agricultural waste (Sawatdeenarunat et al., 2015). According to Tufaner and Avs ¸ ar (2016), anaerobic mono-digestion of cattle dung usually causes poor performance and stability, but cattle dung may resolve any imbalance and improve biogas production when it is combined * Corresponding author. Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Assam 781039, India. ** Corresponding author. Center for Energy, Indian Institute of Technology Guwahati, Assam, 781039, India. E-mail addresses: latha_rangan@yahoo.com (L. Rangan), pinak@iitg.ernet.in (P. Mahanta). 1 Equal contribution. Contents lists available at ScienceDirect International Biodeterioration & Biodegradation journal homepage: www.elsevier.com/locate/ibiod http://dx.doi.org/10.1016/j.ibiod.2016.09.007 0964-8305/© 2016 Elsevier Ltd. All rights reserved. International Biodeterioration & Biodegradation xxx (2016) 1e7 Please cite this article inpress as: Yadav, D., et al., An assessment of duckweed as a potential lignocellulosic feedstock for biogas production, International Biodeterioration & Biodegradation (2016), http://dx.doi.org/10.1016/j.ibiod.2016.09.007