Using porphyritic andesite as a new additive for improving hydrolysis and acidogenesis of solid organic wastes

The effects of porphyritic andesite on the hydrolysis and acidogenesis of solid organic wastes were investigated by batch and continuous experiments using a rotational drum fermentation system. The results of the batch experiment show that if porphyritic andesite (1%, 3%, and 5% reactants) is added initially, the pH level increases and hydrolysis and acidogenesis are accelerated. The highest surface based hydrolysis constant (26.4 × 10−3 kg m−2 d−1) and volatile solid degradation ratio (43.3%) were obtained at a 1% porphyritic andesite addition. In the continuous experiment, porphyritic andesite elevated the first order hydrolysis constant from 13.10 × 10−3 d−1 to 18.82 × 10−3 d−1. A particle mean diameter reduction rate of 33.05 μm/d and a volatile solid degradation rate of 3.53 g/L d−1 were obtained under the hydraulic retention time of 4, 8, 12 and 16 d.