Abstract
Increasing biogas production from municipal anaerobic digesters via additional loading with industrial/agricultural wastes offers a low-cost, sustainable energy generation option of significant untapped potential. In this work, bench-top reactors were used to mimic a full-scale primary sludge digester operating at an organic loading rate (OLR) of 2.4 kg COD/m3 d and a 20 d hydraulic retention time (HRT). Co-digestion of whey with primary sludge was sustained at a loading rate of 3.2 kg COD/m3 d (17 d HRT) and boosted gas production to 151% compared to primary sludge digestion alone. Addition of chemical alkalinity enabled co-digestion of whey with primary sludge to be maintained at an elevated OLR of 6.4 kg COD/m3 d (11 d HRT) with gas production increased to 208%. However, when the chemical addition was simply replaced by cow manure, stable operation was maintained at OLRs of 5.2–6.9 kg COD/m3 d (11–14 d HRT) with gas production boosted up to 268%.
Published Version
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