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Improvement by Micro-Aeration of Anaerobic Digestion of Slaughterhouse Wastewater At 38°C

Abstract

The anaerobic digestion of slaughterhouse wastewaters, used as a model of fluids with high TSS content, was improved by application of micro-aeration of the influent. Digestibility of the total suspended solids (TSS) was improved to prevent their accumulation in the sludge and protect methanogens from their inhibition effect. This was ensured by a controlled dissolution of oxygen in the influent, prior to the anaerobic digestion, by continuous aeration with air at a rate of 15 ml/min, corresponding to 0.05 vvm (volume of air per volume of feeding solution per minute). The methane production yields were of almost 350 and 200 ml CH4 per removed g of CODsol and CODtot, respectively. The micro-aeration of the influent also lead to application of higher organic loads to the treatment system, besides the high methane production yields. These results were obtained at 38°C, which is not common and suitable to anaerobic digestion, but appropriate for enhanced hydrolytic enzymes activities. It was clearly shown, that the improvement of methane production yields was associated to dissolution of TSS. These findings are of great importance from the practical point of view, and technically evidence the emerging idea of tolerance of low aeration in anaerobic technologies

Nabil Zouari, Hayat Al Jabiri

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