The cumulative CH4 production in four digesters, as illustrated
in Fig. 1C, exhibited significantly different results. The highest
cumulative CH4 yield was obtained in digester PPW-FR-1 (273 L/
kg VSfed), which was 14% higher than that using PPW as feedstock
in digester PPW-1. A similar study found that a higher CH4 potential
was obtained from the lactic acid fermentation residue of