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Enhancing methane production of excess sludge and dewatered sludge with combined low frequency CaO-ultrasonic pretreatment

Yuan, Hairong, Guan, Ruolin, Wachemo, Akiber Chufo, Zhu, Chao, Zou, Dexun, Li, Ying, Liu, Yanping, Zuo, Xiaoyu, Li, Xiujin
Bioresource technology 2019 v.273 pp. 425-430
acetic acid, anaerobic digestion, biodegradability, ethanol, methane production, sludge
Methane production of excess sludge (ES) and dewatered sludge (DS) were investigated with low frequency CaO-ultrasonic pretreatment. The results showed that the concentrations of SCOD and VFAs in pretreated ES (P-ES) and DS (P-DS) were 212.11% and 75.26%, 270.30% and 159.52% higher than those of untreated ES and DS, respectively. The contents of acetic acid and ethanol comprised 83.87%–92.88% of the total VFAs. The cumulative methane production (CMP) of P-ES and P-DS were 167.08 and 162.96 mL/g·VS, respectively, which resulted in 40.45% and 36.94% higher than those of untreated ones. The biodegradability of P-ES was 87.65%, which was close to theoretical value. Low frequency CaO-ultrasonic pretreatment could not only improve the performance of anaerobic digestion (AD), but also accelerate the decomposition rate of two kinds of sludge. Therefore, this study provided meaningful insight for exploring efficient pretreatment strategy to stabilize and enhance AD performance for practical application.