Abstract

The high portions of organic and Greasy constituents of the Induced Air Flotation (IAF) unit skim that is typically land disposed or rendered have made it environmentally problematic for the receiving bodies due to its poor natural solubility and degradability. One solution for that was the use of anaerobic digestion. Five laboratory scale batch reactors (each of 10 L working volume) were used in this study to test the effect of different IAF skim to working volume ratios; namely 0.5, 1.5, 2.5, 4.0, 5.0:10 (R1-R5), with the rest of working volume to be filled with livestock manure (as inoculums). These five reactors were operated at two different temperatures (25C and 45C), to determine the temperature effects on digestion performance. COD removal efficiencies of 72.6%, 68.6%, 60.1%, 52.1%, and 43.25% were achieved for R1-R5 respectively, at temperature of 25C. These removal efficiencies were significantly improved when operating these reactors at temperature of 45C, where efficiencies of 91.2%, 81.5%, 72.1%, 60.7% and about 50% were achieved for these reactors. In addition to the achievement of good removal efficiencies regarding the COD and TSS, very promising biogas production rates were determined to have average values of 4.5- 5.8 l/day at operation temperatures of 45C (compared with 3- 4 l/day at 25C) for the majority reactor life times. This achievement may compensate the treatment costs in addition to the supply of cheap renewable energy.

Author would like to acknowledge the logistic and technical support of the Institute of International Education IIE, Scholars Rescue Fund SRF and Russ College of Engineering/ Ohio University. 

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