Int. Journal of Renewable Energy Development 6 (1) 2017: 37-44 Page | 37 © IJRED – ISSN: 2252-4940, February 15 th 2017, All rights reserved Contents list available at IJRED website Int. Journal of Renewable Energy Development (IJRED) Journal homepage: http://ejournal.undip.ac.id/index.php/ijred Kinetic and Enhancement of Biogas Production for The Purpose of Renewable Fuel Generation by Co-digestion of Cow Manure and Corn Straw in A Pilot Scale CSTR System Jabraeil Taghinazhad *a , Reza Abdi b , and Mehrdad Adl c a PhD Candidate, Biosystem Engineering, University of Tabriz, Tabriz, Iran b Department of Biosystem Engineering, University of Tabriz, Tabriz, Iran c Materials and Energy Research Center (MERC), Karaj, Iran ABSTRACT. Biogas production from anaerobic co-digestion of cow manure (CM) and corn straw residue (CSR) were experimentally investigated using a completely stirred tank reactor (CSTR) under semi- continuously feeding circumstance at mesophilic (35°C±2) temperature. The pilot-scale digester with 180 L in volume was employed under experimental protocol to examine the effect of the change in organic loading rate on efficiency of biogas production and to report on its steady-state performance. An average organic loading rates of 2 and 3 kg VS. (m -3 .d -1 ) and a hydraulic retention time (HRT) of 25 days was examined with respect to two different CM to CSR mixing ratios of 100:0 , 75:25 and 50:50, respectively. The results showed both organic loading rates at co-digestion of CM+ CSR gave better methane yields than single digestion of cow manure. The biogas production efficiency was obtained 0.242, 0.204, 0.311 0.296, 259.5 and 235 m 3 .(kg VS input) -1 for 2 and 3 kg VS.(m -3 .d -1 ) at CM to CSR mixing ratios of100:0 , 75:25 and 50:50, respectively. The reactor showed stable performance with VS reduction between 55- 74% during different runs. With increment of loading rate, the VS degradation and biogas yield decreased. Modified Gompertz and logistic plot equation was employed to model the methane production at different organic loading rates and substrate concentrations. The equations gave a good approximation of the maximum methane production (rm) and the methane yield potential (P) with correlation coefficient (R 2 ) over 0.99. Keywords: Biogas; cow manure; corn straw; Kinetic; semi-continuously Article History: Received Oct 25 th 2016; Received in revised form Dec 19 th 2016; Accepted 2 nd January 2017; Available online How to Cite This Article: Taghinazhad. J., Abdi, R. and Adl, M. (2017). Kinetic and Enhancement of Biogas Production for the purpose of renewable fuel generation by Co-digestion of Cow Manure and Corn Straw in a Pilot Scale CSTR System. Int Journal of Renewable Energy Development, 6(1),37-44 http://dx.doi.org/10.14710/ ijred.6.1.37-44 * Corresponding author: taghinazhad55@gmail.com 1. Introduction One of the renewable energy sources is biogas for fossil fuel, which is made from innocuous, safe and biodegradable in the environment such as municipal waste, industrial waste and agricultural, animal and domestic wastes (Omer et al., 2002). Anaerobic digestion (AD) is decomposition of organic matter such as manure, crop residues in the absence of oxygen by concerted action of different groups of anaerobic bacteria. The AD process that is an important energy source produces biogas that the main component composed of methane (CH4), and carbon dioxide (CO2) which can be consumed as an energy source. Biogas can be can be directly burned in a combined and heat power unit for the generation of heat and electricity (Ray et al., 2016; Song et al., 2012). Biogas produced from biogenic material, the feedstock used for biogas production constitute of mono substrate or co-digestion of mixture of several organic materials depending on the reactor technology, availability of feedstock, economic consideration etc., is a type of biofuel (Themelis, & Ulloa, 2007). AD of organic materials to biogas is characterized by the four major steps: hydrolysis, acidogensis, acetogenesis and methanogenesis consecutively. All the mentioned steps run almost at the same time in a biogas reactor. Nearly seventy percent of methane from biogas reactors fed with cattle manure is derived from acetate (Umar et al., 2013; Zhang & Zhang, 1999). The quantity and quality of biogas depend on characteristics of feedstock as well as process conditions. Anaerobic fermentation of animal slurry for biogas generation is commonly tested in continuously stirred