title: Novel anaerobic digestion process with sludge ozonation for economically feasible power production from biogas.
abstract: A novel process scheme was developed to achieve economically feasible energy recovery from anaerobic digestion. The new process scheme employs a hybrid configuration of mesophilic and thermophilic anaerobic digestion with sludge ozonation: the ozonated sludge is first degraded in a thermophilic digester and then further degraded in a mesophilic digester. In small-scale pilot experiments of the new process scheme, degradation of VSS improved by 3.5% over the control (mesophilic-only configuration) with 20% less ozone consumption. Moreover, biogas conversion also improved by 7.1% over the control. Selective enrichment of inorganic compounds during centrifugation produced a dewatered sludge cake with very low water content (59.4%). This low water content in the sludge cake improved its auto-thermal combustion potential during incineration and added to the overall energy savings. We conducted a case study to evaluate power generation from biogas for a municipal wastewater treatment plant with an average dry weather flow of 43,000 m3/d. Electricity production cost was 5.2 ¢/kWh for the advanced process with power generation, which is lower than the current market price of 7.2 ¢/kWh. The new anaerobic digestion scheme with power generation may reduce greenhouse gas emissions by about 1,000 t-CO(2)/year compared with the conventional process without power generation.
authors.affiliation: Kurita Water Industries Ltd., Kawada, Nogi, Tochigi, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Komatsu
authors.forename: H
authors.initials: H
authors.lastname: Yasui
authors.forename: R
authors.initials: R
authors.lastname: Goel
authors.forename: Y Y
authors.initials: YY
authors.lastname: Li
authors.forename: T
authors.initials: T
authors.lastname: Noike
mesh_terms: D001421:Bacteria, Anaerobic / Q000378:metabolism; D001674:Bioelectric Energy Sources; D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology; D003246:Conservation of Energy Resources; D008697:Methane / Q000378:metabolism; D010083:Oxidants, Photochemical; D010126:Ozone; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D056804:Biofuels; D010083:Oxidants, Photochemical; D012722:Sewage; D010126:Ozone; D008697:Methane