Effect of acid, heat and combined acid-heat pretreatments of anaerobic sludge on hydrogen production by anaerobic mixed cultures

Activated sludge (AS) from wastewater treatment plant of brewery industry was used as substrate for hydrogen production by anaerobic mixed cultures in batch fermentation process. The AS (10% TS) was pretreated by acid, heat and combined acid and heat. Combined acid- heat treatment (0.5% (w/v) HCl, 110 °C, 60 min) gave the highest soluble COD (sCOD) of 1785.6 ± 27.1 mg/L with the highest soluble protein and carbohydrate of 8.1 ± 0.1 and 38.5 ± 0.8 mg/L, respectively. After the pretreatment, the pretreated sludge was used to produce hydrogen by heat treated upflow anaerobic sludge blanket (UASB) granules. A maximum hydrogen production potential of 481 mL H2/L was achieved from the AS pretreated with acid (0.5% (w/v) HCl) for 6 h.