Effect of deflocculation on the efficiency of low-energy microwave pretreatment and anaerobic biodegradation of waste activated sludge. (1st May 2015)

• Record Type: Journal Article
• Authors: Ebenezer, A. Vimala; Arulazhagan, P.; Adish Kumar, S.; Yeom, Ick-Tae; Rajesh Banu, J.
• Is Part Of: Applied energy. Volume 145(2015:May 01)
• Page Start: 104
• Page End: 110
• Publication Date: 2015-05-01
• Subjects: Waste activated sludge -- Sodium tripolyphosphate -- Deflocculation -- Microwave irradiation -- Biogas -- Pretreatment; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2015.01.133
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: Sludge deflocculation was done using sodium tripolyphosphate. 0.175 g/g SS dose of STPP disturbed flocs efficiently. Floc disruption facilitated increase in sludge disintegration efficiency of MW. MW specific energy reduced from 26, 000 to 14, 000 kJ/kg TS for deflocculated sludge. 50.7% of cost reduction in pretreatment can be achieved through deflocculation. Abstract: This study focuses on improving the efficiency of the microwave (MW) pretreatment of waste activated sludge (WAS) through deflocculation mediated by sodium tripolyphosphate (STPP), a cationic binding agent. Deflocculated sludge was subjected to MW pretreatment to assess its impact on biomass disintegration. At the optimised energy for MW pretreatment (14, 000 kJ/kg TS), the chemical oxygen demand (COD) solubilisation was 28% and 21% and the reduction in suspended solids (SS) was 38% and 26%, respectively, for deflocculated (treated with a cationic binding agent followed by microwaves) and flocculated (treated by microwaves alone) sludge samples. The formation of volatile fatty acids in the deflocculated sludge medium (840 mg/L) was comparatively higher than that in the flocculated sludge (420 mg/L) and the control (62 mg/L). This study indicates that deflocculated sludge is more amenable to hydrolysis. The results of a test of biochemical methane potential also confirmed the greater amenability of deflocculated sludge for anaerobic degradation.