Bio-electrohydrolysis as a pretreatment strategy to catabolize complex food waste in closed circuitry: Function of electron flux to enhance acidogenic biohydrogen production K. Chandrasekhar a,b , S. Venkata Mohan a,b,* a Bioengineering and Environmental Science (BEES), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India b Academy of Scientific and Innovative Research (AcSIR), India article info Article history: Received 27 February 2014 Received in revised form 1 May 2014 Accepted 5 May 2014 Available online 14 June 2014 Keywords: Self-induced potential Biotransformation Bio-electricity Dehydrogenase activity Tafel analysis Electron acceptor abstract A novel bio-electrohydrolysis system (BEH) based on self-inducing electrogenic activity was designed as a pretreatment device to enhance biohydrogen (H 2 ) production efficiency of food waste. Experimental strategy involved two-stage integrated/hybrid operation with hydrolysis in initial stage followed by acidogenic fermentation for H 2 production in second stage. After pre-treatment, catabolized food waste from control (anaerobic) and BEH (closed circuit mode of operation) system was used as substrate in a separate bioreactor to evaluate H 2 production in dark-fermentation process. Pretreated-waste from BEH showed higher H 2 production (29.12 ml/h; 24th h) than control (26.75 ml/h; 16th h). Higher cumu- lative H 2 production and maximum substrate degradation were also noticed with BEH- pretreated substrate (CHP, 0.91 l; COD, 52.42%) than control (CHP, 0.68 l; COD, 43.68%). Under closed circuitry, anode served as an alternative electron acceptor promoting biotransformation of complex organics to simpler molecules through catabolism. Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. Introduction Biohydrogen (H 2 ) production using dark-fermentation process from renewable sources such as biomass and wastewater using mixed biocatalyst is generally preferred because of lower cost of raw material, ease of control and the possibility of using a wide range of organic waste as feedstock [1e13]. Exploitation of wastewater as substrate for H 2 production with concurrent wastewater treatment is an attractive and effec- tive way of tapping clean energy from renewable resources in a sustainable approach [14e16]. The process yields dual benefit to the environment in terms of renewable energy generation with simultaneous waste stabilization. One of the major challenges that persist with the dark-fermentation process is the rate and yield of H 2 production. Substrate/ feed-stock and its composition are one of the rate limiting factors that persist with the dark-fermentative H 2 production * Corresponding author. Bioengineering and Environmental Science (BEES), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500 007, India. Tel./fax: þ91 40 27191664. E-mail addresses: vmohan_s@yahoo.com, svmohan@iict.res.in (S. Venkata Mohan). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 39 (2014) 11411 e11422 http://dx.doi.org/10.1016/j.ijhydene.2014.05.035 0360-3199/Copyright © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.