Ammonia Stripping of Piggery Wastewater for Enhanced Methanization

摘要

In this study, we systematically evaluated the feasibility of air stripping as a pretreatment of anaerobic digestion of piggery wastewater. The effects of ammonia and sodium ion on anaerobic digestion were investigated by bath experiments using both unacclimated and acclimated inocula. Furthermore, the effects of different air stripping pretreatment conditions on methanization of piggery wastewater were also evaluated by semi-continuous experiment. Batch tests showed that ammonia exerted strong inhibitory effects on anaerobic digestion with IC50 of 2.22 and 4.03 g NH3-N/L for unacclimated and acclimated inocula, respectively. Air stripping effectively removed the ammonia at pH higher than 9.0. Batch toxicity results showed that excess sodium ion addition inhibited methanogen activity with IC50 of 4.93 g/L as Na~+ Enhanced methanization of anaerobic digestion of air stripped piggery wastewaters at pH 9.5 and pH 10 was observed in semi-continuous experiments. However, the methane production rate from anaerobic digestion of air stripped piggery wastewater at pH 11 continuously declined due to sodium inhibition (7.63 g/L of Na~+).