Examination of microbial fuel cell start-up times with domestic wastewater and additional amendments Guangli Liu a , Matthew D. Yates b , Shaoan Cheng b,c , Douglas F. Call b , Dan Sun d , Bruce E. Logan b,⇑ a School of Environmental Science & Engineering, Sun Yat-sen University, Guangzhou 510275, PR China b Department of Civil & Environmental Engineering, Penn State University, 231Q Sackett Building, University Park, PA 16802, USA c State Key Laboratory of Clean Energy Utilization, Department of Energy Engineering, Zhejiang University, Hangzhou 310027, PR China d State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology (SKLUWRE, HIT), Harbin 150090, PR China article info Article history: Received 19 February 2011 Received in revised form 21 April 2011 Accepted 27 April 2011 Available online 30 April 2011 Keywords: Microbial fuel cell Domestic wastewater Startup time Substrate abstract Rapid startup of microbial fuel cells (MFCs) and other bioreactors is desirable when treating wastewaters. The startup time with unamended wastewater (118 h) was similar to that obtained by adding acetate or fumarate (110–115 h), and less than that with glucose (181 h) or Fe(III) (353 h). Initial current production took longer when phosphate buffer was added, with startup times increasing with concentration from 149 h (25 mM) to 251 h (50 mM) and 526 h (100 mM). Microbial communities that developed in the reactors contained Betaproteobacteria, Acetoanaerobium noterae, and Chlorobium sp. Anode biomass den- sities ranged from 200 to 600 lg/cm 2 for all amendments except Fe(I) (1650 lg/cm 2 ). Wastewater pro- duced 91 mW/m 2 , with the other MFCs producing 50 mW/m 2 (fumarate) to 103 mW/m 2 (Fe(III)) when amendments were removed. These experiments show that wastewater alone is sufficient to acclimate the reactor without the need for additional chemical amendments. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Microbial fuel cell (MFCs) are a promising approach for treating wastewater, as electricity is produced directly from the process of organics biodegradation (Logan, 2009; Logan, 2010). Many kinds of wastewaters have been tested in recent years, including synthetic, domestic and industrial wastewaters (He et al., 2005; Huang and Logan, 2008; Ahn and Logan, 2009). A number of factors should be addressed before MFC technologies can be applied at larger scales. Previous research has focused on anode and cathode mate- rials, separators, and designs for scaling-up reactors. However, ra- pid start-up of any biological process used for wastewater treatment is desirable to avoid discharge of untreated wastewater. Reported startup times for MFCs vary depending on the sub- strates examined and the reactor architecture, ranging from 10s of hours to several months (Feng et al., 2008; Liu et al., 2008). For example, more than 50 h was needed to obtain maximum volt- ages in two-chamber, air-cathode MFCs inoculated with anaerobic sludge (Kim et al., 2005). Liu and Logan (2004) demonstrated that the single-chamber, air-cathode MFC could produce a consistent maximum voltage after 140 h (0.32 V, 4 cycles) when inoculated with the effluent of a primary sedimentation tank, but a stacked MFC using a ferricyanide catholyte required 103 days following inoculation with a mixture of anaerobic and aerobic sludge (Ael- terman et al., 2006). A cassette-electrode MFC with air-cathodes took 15 days before stable performance was achieved with a syn- thetic wastewater (Shimoyama et al., 2008). One of the most effi- cient methods for starting up a new MFC is to use the effluent from an existing reactor treating the same type of substrate (Jung and Regan, 2007; Chae et al., 2009; Kim et al., 2007). However, a large volume of pre-acclimated exoelectrogens may not be avail- able for starting-up larger scale reactors. For example, a 1000 L pi- lot-scale microbial electrolysis cell (MEC) had to be inoculated with domestic wastewater to treat winery wastewater, and it re- quired 60 days for start up (Cusick et al., 2011). Thus, more infor- mation is needed on how to start up larger reactors in the absence of a pre-acclimated inoculum. In the case of domestic wastewater treatment, it is not known if startup can be accelerated or subsequent performance can be improved through creating dif- ferent conditions in the wastewater during the start up phase of operation. Several approaches can be used to improve startup. First, addi- tional substrates can be added since the wastewater strength is typically lower than that used in laboratory systems (1 g/L chem- ical oxygen demand, COD). Second, the addition of specific alter- nate electron acceptors can be used to encourage the growth of known exoelectrogenic bacteria such as various Geobacter or Shewanella species. Fumarate or Fe(III) is often used to culture Geobacter sulfurreducens prior to inoculation into an MFC (Wang et al., 2010; Torres et al., 2009), although fumarate can also be used 0960-8524/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2011.04.087 ⇑ Corresponding author. Tel.: +1 814 863 7908; fax: +1 814 863 7304. E-mail address: blogan@psu.edu (B.E. Logan). Bioresource Technology 102 (2011) 7301–7306 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech