title: Linking biofilm growth to fouling and aeration performance of fine-pore diffuser in activated sludge.
abstract: Aeration is commonly identified as the largest contributor to process energy needs in the treatment of wastewater and therefore garners significant focus in reducing energy use. Fine-pore diffusers are the most common aeration system in municipal wastewater treatment. These diffusers are subject to fouling and scaling, resulting in loss in transfer efficiency as biofilms form and change material properties producing larger bubbles, hindering mass transfer and contributing to increased plant energy costs. This research establishes a direct correlation and apparent mechanistic link between biofilm DNA concentration and reduced aeration efficiency caused by biofilm fouling. Although the connection between biofilm growth and fouling has been implicit in discussions of diffuser fouling for many years, this research provides measured quantitative connection between the extent of biofouling and reduced diffuser efficiency. This was clearly established by studying systematically the deterioration of aeration diffusers efficiency during a 1.5 year period, concurrently with the microbiological study of the biofilm fouling in order to understand the major factors contributing to diffuser fouling. The six different diffuser technologies analyzed in this paper included four different materials which were ethylene-propylene-diene monomer (EPDM), polyurethane, silicone and ceramic. While all diffusers foul eventually, some novel materials exhibited fouling resistance. The material type played a major role in determining the biofilm characteristics (i.e., growth rate, composition, and microbial density) which directly affected the rate and intensity at what the diffusers were fouled, whereas diffuser geometry exerted little influence. Overall, a high correlation between the increase in biofilm DNA and the decrease in αF was evident (CV < 14.0 ± 2.0%). By linking bacterial growth with aeration efficiency, the research was able to show quantitatively the causal connection between bacterial fouling and energy wastage during aeration.
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA. Electronic address: manelg@uci.edu.
authors.forename: Manel
authors.initials: M
authors.lastname: Garrido-Baserba
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA; Department of Civil Engineering and Construction Engineering Management, California State University, Long Beach, CA 90840, USA.
authors.forename: Pitiporn
authors.initials: P
authors.lastname: Asvapathanagul
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA.
authors.forename: Graham W
authors.initials: GW
authors.lastname: McCarthy
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA.
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Gocke
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA 92697-2175, USA.
authors.forename: Betty H
authors.initials: BH
authors.lastname: Olson
authors.affiliation: School of Civil, Environmental and Architectural Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-713, South Korea.
authors.forename: Hee-Deung
authors.initials: HD
authors.lastname: Park
authors.affiliation: DC Water, 5000 Overlook Ave SW, Washington, DC 20032, USA.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Al-Omari
authors.affiliation: DC Water, 5000 Overlook Ave SW, Washington, DC 20032, USA.
authors.forename: Sudhir
authors.initials: S
authors.lastname: Murthy
authors.affiliation: Hampton Roads Sanitation District, Virginia Beach, VA 23471-0911, USA.
authors.forename: Charles B
authors.initials: CB
authors.lastname: Bott
authors.affiliation: ARAconsult, Unterbergerstraße 1, A-6020 Innsbruck, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Wett
authors.affiliation: United States Environmental Protection Agency, 1200 Pennsylvania Ave NW, Washington, DC 20460, USA.
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Smeraldi
authors.affiliation: Black & Veatch, 8400 Ward Pkwy, Kansas City, MO 64114, USA.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Shaw
authors.affiliation: Department of Civil & Environmental Engineering, University of California, Irvine, CA 92697-2175, USA; Water-Energy Nexus Center, University of California, Irvine, CA 92697-2175, USA. Electronic address: bidui@uci.edu.
authors.forename: Diego
authors.initials: D
authors.lastname: Rosso
mesh_terms: D018441:Biofilms; D057219:Biofouling; D002516:Ceramics / Q000737:chemistry; D004269:DNA, Bacterial / Q000032:analysis; D003851:Deoxyribonucleases / Q000737:chemistry; D004058:Diffusion; D020724:Elastomers / Q000737:chemistry; D004867:Equipment Design; D005030:Ethylenes / Q000737:chemistry; D059013:Microbial Consortia; D018613:Microscopy, Confocal; D010100:Oxygen / Q000737:chemistry; D011312:Pressure; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D004269:DNA, Bacterial; D003851:Deoxyribonucleases; D020724:Elastomers; D005030:Ethylenes; D010100:Oxygen; D012722:Sewage; D062065:Wastewater; C505585:ethylene-propylene-diene-monomer
keywords: Activated sludge; Aeration; Biofilm; Efficiency; Fine-pore diffuser; Fouling