title: Evaluation of a biological wastewater treatment system combining an OSA process with ultrasound for sludge reduction.
abstract: Sludge production is an undesirable by-product of biological wastewater treatment. The oxic-settling-anaerobic (OSA) process constitutes one of the most promising techniques for reducing the sludge produced at the treatment plant without negative consequences for its overall performance. In the present study, the OSA process is applied in combination with ultrasound treatment, a lysis technique, in a lab-scale wastewater treatment plant to assess whether sludge reduction is enhanced as a result of mechanical treatment. Reported sludge reductions of 45.72% and 78.56% were obtained for the two regimes of combined treatment tested in this study during two respective stages: UO1 and UO2. During the UO1 stage, the general performance and nutrient removal improved, obtaining 47.28% TN removal versus 21.95% in the conventional stage. However, the performance of the system was seriously damaged during the UO2 stage. Increases in dehydrogenase and protease activities were observed during both stages. The advantages of the combined process are not necessarily economic, but operational, as US treatment acts as contributing factor in the OSA process, inducing mechanisms that lead to sludge reduction in the OSA process and improving performance parameters.
authors.affiliation: Department of Environmental Technology, Faculty of Marine and Environmental Sciences, Universidad de Cádiz, Avda. Republica Saharaui S/n, 11510 Puerto Real, Cadiz, Spain. Electronic address: pablo.romero@uca.es.
authors.forename: P M
authors.initials: PM
authors.lastname: Romero-Pareja
authors.affiliation: Foundation Centre for New Water Technologies (CENTA), Seville-Huelva Highway (A-49) km. 28, Carrión de los Céspedes, Seville, Spain. Electronic address: caragon@centa.es.
authors.forename: C A
authors.initials: CA
authors.lastname: Aragon
authors.affiliation: Department of Environmental Technology, Faculty of Marine and Environmental Sciences, Universidad de Cádiz, Avda. Republica Saharaui S/n, 11510 Puerto Real, Cadiz, Spain. Electronic address: josemaria.quiroga@centa.es.
authors.forename: J M
authors.initials: JM
authors.lastname: Quiroga
authors.affiliation: Department of Environmental Technology, Faculty of Marine and Environmental Sciences, Universidad de Cádiz, Avda. Republica Saharaui S/n, 11510 Puerto Real, Cadiz, Spain. Electronic address: dolores.coello@uca.es.
authors.forename: M D
authors.initials: MD
authors.lastname: Coello
mesh_terms: D000641:Ammonia / Q000302:isolation & purification; D000693:Anaerobiosis; D019149:Bioreactors / Q000382:microbiology*; D009566:Nitrates / Q000302:isolation & purification; D009584:Nitrogen / Q000302:isolation & purification; D010088:Oxidoreductases / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D010710:Phosphates / Q000302:isolation & purification; D012722:Sewage / Q000382:microbiology*; D013010:Sonication; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D000641:Ammonia; D009566:Nitrates; D009584:Nitrogen; D010088:Oxidoreductases; D010447:Peptide Hydrolases; D010710:Phosphates; D012722:Sewage; D062065:Wastewater
keywords: Activated sludge process; OSA process; Sludge lysis; Sludge reduction; Ultrasound