title: Enhancement of sludge anaerobic biodegradability by combined microwave-H2O2 pretreatment in acidic conditions.
abstract: The aim of this study was to increase the sludge disintegration and reduce the cost of microwave (MW) pretreatment. Thermodynamic analysis of MW hydrolysis revealed the best fit with a first-order kinetic model at a specific energy of 18,600 kJ/kg total solids (TS). Combining H2O2 with MW resulted in a significant increment in solubilization from 30 to 50 % at 18,600 kJ/kg TS. The pH of H2O2-assisted MW-pretreated sludge (MW + H2O2) was in the alkaline range (pH 9-10), and it made the sludge unfavorable for subsequent anaerobic digestion and inhibits methane production. In order to nullify the alkaline effect caused by the MW + H2O2 combination, the addition of acid was considered for pH adjustment. H2O2-assisted MW-pretreated sludge in acidic conditions (MW + H2O2 + acid) showed a maximum methane production of 323 mL/g volatile solids (VS) than others during anaerobic biodegradability. A cost analysis of this study reveals that MW + H2O2 + acid was the most economical method with a net profit of 59.90 €/t of sludge.
authors.affiliation: Department of Civil Engineering, Regional Centre of Anna University, Tirunelveli, 627007, India.
authors.forename: Parvathy
authors.initials: P
authors.lastname: Eswari
authors.affiliation: Department of Civil Engineering, Regional Centre of Anna University, Tirunelveli, 627007, India.
authors.forename: S
authors.initials: S
authors.lastname: Kavitha
authors.affiliation: Department of Civil Engineering, Ponjesly College of Engineering, Nagercoil, India.
authors.forename: S
authors.initials: S
authors.lastname: Kaliappan
authors.affiliation: Department of Civil and Environmental Engineering, Sungkyunkwan University, Seoul, South Korea.
authors.forename: Ick-Tae
authors.initials: IT
authors.lastname: Yeom
authors.affiliation: Department of Civil Engineering, Regional Centre of Anna University, Tirunelveli, 627007, India. rajeshces@gmail.com.
authors.forename: J Rajesh
authors.initials: JR
authors.lastname: Banu
mesh_terms: D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008697:Methane / Q000378:metabolism; D008872:Microwaves; D012722:Sewage; D014865:Waste Disposal, Fluid / Q000379:methods
chemical_list: D012722:Sewage; D006861:Hydrogen Peroxide; D008697:Methane
keywords: Advanced oxidation processes; Anaerobic biodegradability; Biogas production; Combined pretreatment; Cost analysis; Microwave; Sludge disintegration