title: Anaerobic digestion of ultrasonicated sludge at different solids concentrations - Computation of mass-energy balance and greenhouse gas emissions.
abstract: Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10(6) g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output - energy input) of total dry solids (TDS) was 7.89 × 10(-6) kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge.
authors.affiliation: INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec, G1K 9A9, Canada.
authors.forename: Sridhar
authors.initials: S
authors.lastname: Pilli
authors.affiliation: INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec, G1K 9A9, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Yan
authors.affiliation: INRS Eau, Terre, Environnement, 490, rue de la Couronne, Québec, G1K 9A9, Canada. Electronic address: tyagi@ete.inrs.ca.
authors.forename: R D
authors.initials: RD
authors.lastname: Tyagi
authors.affiliation: Dept. of Civil Engineering, University of Nebraska-Lincoln, N104 SEC, P. O. Box 886105, Lincoln, 68588-610, USA.
authors.forename: R Y
authors.initials: RY
authors.lastname: Surampalli
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism; D001673:Biodegradation, Environmental; D002245:Carbon Dioxide / Q000032:analysis; D003246:Conservation of Energy Resources; D008697:Methane / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D059205:Renewable Energy; D012722:Sewage / Q000737:chemistry*; D013010:Sonication; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D012722:Sewage; D002245:Carbon Dioxide; D009609:Nitrous Oxide; D008697:Methane
keywords: Biodegradability anaerobic digestion; Mass-energy balance and greenhouse gas emissions; Pre-treatment