title: Sorption and release of organics by primary, anaerobic, and aerobic activated sludge mixed with raw municipal wastewater.
abstract: New activated sludge processes that utilize sorption as a major mechanism for organics removal are being developed to maximize energy recovery from wastewater organics, or as enhanced primary treatment technologies. To model and optimize sorption-based activated sludge processes, further knowledge about sorption of organics onto sludge is needed. This study compared primary-, anaerobic-, and aerobic activated sludge as sorbents, determined sorption capacity and kinetics, and investigated some characteristics of the organics being sorbed. Batch sorption assays were carried out without aeration at a mixing velocity of 200 rpm. Only aerobic activated sludge showed net sorption of organics. Sorption of dissolved organics occurred by a near-instantaneous sorption event followed by a slower process that obeyed 1st order kinetics. Sorption of particulates also followed 1st order kinetics but there was no instantaneous sorption event; instead there was a release of particles upon mixing. The 5-min sorption capacity of activated sludge was 6.5±10.8 mg total organic carbon (TOC) per g volatile suspend solids (VSS) for particulate organics and 5.0±4.7 mgTOC/gVSS for dissolved organics. The observed instantaneous sorption appeared to be mainly due to organics larger than 20 kDa in size being sorbed, although molecules with a size of about 200 Da with strong UV absorbance at 215-230 nm were also rapidly removed.
authors.affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: Oskar
authors.initials: O
authors.lastname: Modin
authors.affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: Soroush
authors.initials: S
authors.lastname: Saheb Alam
authors.affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: Frank
authors.initials: F
authors.lastname: Persson
authors.affiliation: Division of Water Environment Technology, Department of Civil and Environmental Engineering, Chalmers University of Technology, Gothenburg, Sweden.
authors.forename: Britt-Marie
authors.initials: BM
authors.lastname: Wilén
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D001386:Azides / Q000494:pharmacology; D001673:Biodegradation, Environmental; D002947:Cities; D007700:Kinetics; D009930:Organic Chemicals / Q000737:chemistry* / Q000302:isolation & purification* / Q000378:metabolism; D012722:Sewage / Q000382:microbiology; D018505:Waste Management; D062065:Wastewater / Q000737:chemistry*
chemical_list: D001386:Azides; D009930:Organic Chemicals; D012722:Sewage; D062065:Wastewater