title: Using mechanisms of hydrolysis and sorption to reduce siloxanes occurrence in biogas of anaerobic sludge digesters.
abstract: Hydrolysis of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6) and dodecamethylcyclohexasilane (D6_silane) and their sorption to digested sludge was studied in batch experiments. Hydrolysis was affected by the type of the compound and the applied temperature, while the relevant half-life values ranged between 0.07±0.01d (D3, 55°C) and 48.4±17.1d (D6_silane, 4°C). D5 showed the greatest affinity for sorption to digested sludge (logKd: 3.84±3.42), the lowest LogKdvalue was found for D3 (1.46±0.95). Prediction of investigated compounds' fate in a single-stage anaerobic digestion system indicated that volatilization seems to be the major fate in both mesophilic and thermophilic conditions. The addition of a pre-digester with 3d retention time would significantly decrease the expected concentrations of all siloxanes in biogas, enhancing their removal through hydrolysis and sorption to sludge.
authors.affiliation: Department of Environment, University of the Aegean, 81100 Mytilene, Greece.
authors.forename: Georgia
authors.initials: G
authors.lastname: Gatidou
authors.affiliation: Department of Environment, University of the Aegean, 81100 Mytilene, Greece.
authors.forename: Olga S
authors.initials: OS
authors.lastname: Arvaniti
authors.affiliation: Department of Environment, University of the Aegean, 81100 Mytilene, Greece. Electronic address: astas@env.aegean.gr.
authors.forename: Athanasios S
authors.initials: AS
authors.lastname: Stasinakis
authors.affiliation: Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece.
authors.forename: Nikolaos S
authors.initials: NS
authors.lastname: Thomaidis
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljøvej 115, 2800 Kgs. Lyngby, Denmark.
authors.forename: Henrik R
authors.initials: HR
authors.lastname: Andersen
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels / Q000032:analysis; D008401:Gas Chromatography-Mass Spectrometry; D006207:Half-Life; D006868:Hydrolysis; D059625:Liquid-Liquid Extraction; D012722:Sewage / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D013696:Temperature; D014835:Volatilization
chemical_list: D056804:Biofuels; D012722:Sewage; D012833:Siloxanes
keywords: Fate; Hydrolysis; Micropollutants; Sludge treatment; Sorption