Combination of ultrasound and Fenton treatment for improving the hydrolysis and acidification of waste activated sludge

Abstract

The effects of ultrasound (US), Fenton treatment, and combined US/Fenton treatment as physicochemical pretreatment processes for waste activated sludge (WAS) hydrolysis and acidification were investigated in this study. The soluble carbohydrate concentrations after US/Fenton treatment were 2.36-fold, 2.17-fold and 17.11-fold more than that obtained by the Fenton treatment, US and control tests, respectively. The corresponding concentrations of soluble protein after US/Fenton treatment were 2.43-fold, 1.47-fold and 13.37-fold more than that obtained by the Fenton treatment, US and control tests, respectively. The degree of sludge disintegration (DD COD ) for the US/Fenton treatment was 15.4%, whereas it was only 9.97% and 3.18% for the US and Fenton tests. The maximum accumulation of volatile fatty acids (VFAs) was obtained by the US/Fenton pretreatment (4594 mg COD L À1 ), which presented obvious advantages over US (3485 mg COD L À1 ) and Fenton (2700 mg COD L À1) treatments. The combination of the US and Fenton treatments had a synergetic effect on improving the hydrolysis and subsequent acidification of WAS.

Pre-treatments to enhance the biodegradability of waste activated sludge: Elucidating the rate limiting step

“…At pH values of 4 and higher, ferric ion precipitates and loses its catalytic activity (W. Zhang et al, 2015b). For WAS pre-treatment mainly pH values of 2 or 3 have been applied (Bao et al, 2015;Gong et al, 2015). Three features make this technique appealing: a) hydroxyl radical formation; b) low pH similar to acid pre-treatment; and c) improved dewaterability of the digestate due to coagulation by iron addition (Neyens and Baeyens, 2003).…”

Enhanced Short-Chain Fatty Acids from Waste Activated Sludge by Heat–CaO2 Advanced Thermal Hydrolysis Pretreatment: Parameter Optimization, Mechanisms, and Implications

“…However, it was observed in batch tests that the cumulative methane production of the heat–CaO 2 pretreated sludge was 0.4 mL/g VSS and the SCFAs production leveled off after 5 days of fermentation (Figures and ), thus a continuous regulation might be useful for SCFA production in continuous mode, which would be considered in the following work. Besides, when the heat–CaO 2 pretreatment is applyied in the real WWTPs, some issues or studies, such as more detailed running or control parameters, methods for the recovery of released nitrogen and phosphorus in the fermentation liquid, and approaches for the collection and utilization of produced hydrogen, need to be considered or carried out in the future. , …”

A critical review of biogas production and usage with legislations framework across the globe

“…In this field, the highest yield achieved in biogas production was investigated by Bolzonella et al (Bolzonella et al 2012) by applying the pretreatment at 70 °C for 2 days, with associated yield increasing by up to 145%. It is noteworthy to mention that many studies have investigated the combined pretreatment for increasing the biogas production yield (Liu et al 2018;Bao et al 2015;Chan et al 2016;Abelleira-Pereira et al 2015;Wang et al 2014;Bentayeb et al 2013) however, this is out of the scope of this study.…”