Short communication Investigating wastewater modelling as a tool to predict anaerobic decomposition and biogas yield of abattoir effluent Bernadette K. McCabe *, Ihsan Hamawand, Craig Baillie National Centre for Engineering in Agriculture, University of Southern Queensland, Toowoomba, QLD, Australia Introduction Anaerobic ponds are widely used as the first stage of secondary treatment of high strength abattoir wastewater and are an efficient means whereby the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are reduced by around 90% in ideal conditions [1,2]. However, they have a couple of issues including odour emissions and the generation of methane, a powerful greenhouse gas. The concept of covering anaerobic ponds to improve wastewater treatment, reduce odours and capture methane as a renewable energy source has been applied to a number of industries in the treatment of both domestic and industrial waste including the red meat processing industry [3]. This industry produces wastewater with a high pollutant load consisting of paunch, manure, fats, oils and greases (FOGs) and uncollected blood [4]. FOGs are large contributors to BOD and COD and while they have the potential to produce large quantities of methane, their hydrophobic nature tends to result in the formation of a scum or crust layer [5]. This can result in reduced treatment efficiency of the pond and also a loss of valuable organic resource for the conversion of methane. In addition the accumulation of fat on the surface of the ponds can interfere with covers and also hinder the accurate measurement of recoverable quantity and quality of biogas. Computer modelling software has become widely adopted in wastewater engineering over the past two decades. Although evolved principally as a research tool they are now used more for design and optimisation of wastewater treatment plants [6]. BioWin 1 is a windows based computer simulation model which is increasingly used in predicting anaerobic digestion processes and subsequent biogas yield [7]. Although there has been no application of BioWin to predict the anaerobic digestion of meat processing wastewater to date there is scope given the uncertainty surrounding accurate biogas measurements due to crust and solid accumulation. The purpose of this study therefore, was to use BioWin to simulate the behaviour of a covered anaerobic pond treating abattoir wastewater and to estimate the potential biogas production. Journal of Environmental Chemical Engineering xxx (2013) xxx–xxx A R T I C L E I N F O Article history: Received 16 April 2013 Received in revised form 11 July 2013 Accepted 12 July 2013 Keywords: BioWin Slaughterhouse wastewater Covered anaerobic pond Treatment efficiency Biogas A B S T R A C T Due to the high strength nature of abattoir wastewater, the accumulation of crusts on anaerobic ponds is a systemic problem in the red meat processing industry in Australia and can limit the ability to accurately obtain biogas measurements. In this study, BioWin was used to simulate chemical oxygen demand (COD) removal rates and subsequent biogas production rate based on field data from two abattoirs where crust accumulation was an issue. BioWin is a Microsoft Windows-based simulator developed by EnviroSim Associates Ltd, which has seen use in the design and optimisation of wastewater treatment plants. In assessing overall anaerobic decomposition efficiency it was hypothesised that a large percentage of influent COD was present as a surface crust which remained largely unbiodegradable. Field data effluent COD removal rates were matched to simulated rates predicted by BioWin when measured influent COD was reduced to 30% (absolute relative error of 11–14%), thus supporting the notion that a significant portion of COD is not taking part in the anaerobic digestion process. The simulation provides a preliminary assessment of pond performance in terms of COD removal rates and also subsequent biogas production rates. BioWin was able to predict approximate biogas production rates ranging between 113 to 173 m 3 /d and 52 m 3 /d for the two abattoirs investigated. Further work to validate simulation using BioWin includes obtaining actual biogas measurements and performing COD measurement of crust. Crown Copyright ß 2013 Published by Elsevier Ltd. All rights reserved. Abbreviations: BOD, biochemical oxygen demand; COD, chemical oxygen demand; DAF, dissolved air flotation; FOGs, fats, oils and greases; TKN, total Kjeldahl nitrogen; TSS, total suspended solids. * Corresponding author. Tel.: +61 07 46 311 623; fax: +61 07 46 311 530. E-mail addresses: Bernadette.McCabe@usq.edu.au (B.K. McCabe), Ihsan.Hamawand@usq.edu.au (I. Hamawand), Craig.Baillie@usq.edu.au (C. Baillie). G Model JECE-95; No. of Pages 5 Please cite this article in press as: B.K. McCabe, et al., Investigating wastewater modelling as a tool to predict anaerobic decomposition and biogas yield of abattoir effluent, J. Environ. Chem. Eng. (2013), http://dx.doi.org/10.1016/j.jece.2013.07.015 Contents lists available at ScienceDirect Journal of Environmental Chemical Engineering jou r n al h o mep ag e: w ww .elsevier .co m /loc ate/jec e 2213-3437/$ – see front matter . Crown Copyright ß 2013 Published by Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jece.2013.07.015