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.

► Activated sludge (AS) from wastewater treatment plant was used as the substrate.
► AS was pretreated by acid, heat and combined acid-heat before used.
► Combined acid-heat treatment gave the highest soluble COD of 1785.6 mg/L
► Protein and carbohydrate are the main soluble substrate after pretreatment.
► Ps of 481 mL H2/L was achieved from the AS pretreated with 5% w/v of HCl for 6 h.