title: Enhancing the anaerobic digestion potential of dairy waste activated sludge by two step sono-alkalization pretreatment.
abstract: High efficiency resource recovery from dairy waste activated sludge (WAS) has been a focus of attention. An investigation into the influence of two step sono-alkalization pretreatment (using different alkaline agents, pH and sonic reaction times) on sludge reduction potential in a semi-continuous anaerobic reactor was performed for the first time in literature. Firstly, effect of sludge pretreatment was evaluated by COD solubilization, suspended solids reduction and biogas production. At optimized condition (4172 kJ/kg TS of supplied energy for NaOH - pH 10), COD solubilization, suspended solids reduction and biogas production was 59%, 46% and 80% higher than control. In order to clearly describe the hydrolysis of waste activated sludge during sono-alkalization pretreatment by a two step process, concentrations of ribonucleic acid (RNA) and bound extracellular polymeric substance (EPS) were also measured. Secondly, semi-continuous process performance was studied in a lab-scale semi-continuous anaerobic reactor (5L), with 4 L working volume. With three operated SRTs, the SRT of 15 d was found to be most appropriate for economic operation of the reactor. Combining pretreatment with anaerobic digestion led to 58% and 62% of suspended solids and volatile solids reduction, respectively, with an improvement of 83% in biogas production. Thus, two step sono-alkalization pretreatment laid the basis in enhancing the anaerobic digestion potential of dairy WAS.
authors.affiliation: Dept of Civil Engineering, Regional Centre of Anna University, Tirunelveli 627007, India.
authors.forename: R Uma
authors.initials: RU
authors.lastname: Rani
authors.affiliation: Dept of Civil Engineering, Regional Centre of Anna University, Tirunelveli 627007, India.
authors.forename: S Adish
authors.initials: SA
authors.lastname: Kumar
authors.affiliation: Dept of Civil Engineering, Ponjesly College of Engineering, Nagercoil, India.
authors.forename: S
authors.initials: S
authors.lastname: Kaliappan
authors.affiliation: Dept of Civil and Environmental Engineering, Sungkyunkwan University, South Korea.
authors.forename: Ick-Tae
authors.initials: IT
authors.lastname: Yeom
authors.affiliation: Dept of Civil Engineering, Regional Centre of Anna University, Tirunelveli 627007, India. Electronic address: rajeshces@gmail.com.
authors.forename: J Rajesh
authors.initials: JR
authors.lastname: Banu
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D001704:Biopolymers / Q000737:chemistry; D003612:Dairying; D005227:Fatty Acids / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007220:Industrial Waste; D010100:Oxygen / Q000737:chemistry; D012313:RNA / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013010:Sonication; D018505:Waste Management / Q000379:methods*
chemical_list: D056804:Biofuels; D001704:Biopolymers; D005227:Fatty Acids; D007220:Industrial Waste; D012722:Sewage; D012313:RNA; D010100:Oxygen
keywords: Anaerobic digestion; Biodegradability; Biogas; Solubilization; Sono-alkalization pretreatment; Waste activated sludge