Impact of fouling on the decline of aeration efficiency under different operational conditions at WRRFs

• Published in: The Science of the total environment Vol. 639; pp. 248 - 257
• Main Authors: Garrido-Baserba, Manel, Asvapathanagul, Pitiporn, Park, Hee-Deung, Kim, Taek-Seung, Baquero-Rodriguez, G. Andres, Olson, Betty H., Rosso, Diego
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-10-2018
• Subjects: Activated sludge; Aeration; Biofilm; Biofouling; Bioreactors; Diffusion; Efficiency; Fine-pore diffuser; Fouling; Membranes, Artificial; Oxygen; Sewage; Waste Disposal, Fluid - methods; Waste Water; Aeration; Biofilm; Activated sludge; Fine-pore diffuser; Fouling; Efficiency
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2018.05.036

Biofilm formation influences the most energy-demanding process in the waste water treatment cycle. Biofilm growth on the surface of wastewater aeration diffusers in water resource recovery facilities (WRRFs) can increase the energy requirements up to 50% in less than 2 years. The impact of biofilms in aeration diffusers was quantified and assessed for first time using molecular tools (i.e., Energy-dispersive X-ray, Ra and RMS and Pyrosequencing) and state-of-the-art techniques (i.e., EPS quantification, Hydrophobicity and DNA quantification). To provide a better understanding and quantitative connections between biological activity and aeration energy efficiency, two replicates of the most common diffusers were installed and tested in two different operational conditions (higher and lower organic loading rate processes) during 15 months. Different scenarios and conditions provided for first time comprehensive understanding of the major factors contributing to diffuser fouling. The array of analysis suggested that higher loading conditions can promote specialized microbial populations to halve aeration efficiency parameters (i.e., αF) in comparison to lower loading conditions. Biofilms adapted to certain operational conditions can trigger changes in diffuser membrane properties (i.e., biological enhanced roughness and hydrophobicity) and enhance EPS growth rates. Improved understanding of the effects of scaling, biofouling, aging and microbial population shifts on the decrease in aeration efficiency is provided.
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•Quantitative connections between the extent of biofouling and reduced aeration diffuser efficiency•The specific contributions to the decrease in aeration efficiency <αF> were quantified for first time.•Performance decrease is highly influenced by operational conditions and concurrent microbial population shifts.•Molecular tools were applied in order to understand the major factors contributing to diffuser fouling.