title: Complete solids retention activated sludge process.
abstract: In a slaughterhouse's full-scale extended aeration activated sludge wastewater treatment plant (WWTP), operating under complete solids retention time, the evolution of mixed liquor suspended solids (MLSS) and mixed liquor volatile suspended solids (MLVSS) concentration, food to micro-organisms ratio (F/M) and substrate utilization rate (SUR) were studied for over a year. Biomass growth phases in correlation to sludge biological and morphological characteristics were studied. Three distinguished growth phases were observed during the 425 days of monitoring. The imposed operational conditions led the process to extended biomass starvation conditions, minimum F/M, minimum SUR and predator species growth. MLSS and MLVSS reached a stabilization phase (plateau phase) where almost zero sludge accumulation was observed. The concept of degradation of the considered non-biodegradable particulate compounds in influent and in biomass (cell debris) was also studied. Comparison of evolution of observed sludge yields (Yobs) in the WWTP with Yobs predictions by activated sludge models verified the degradation concept for the considered non-biodegradable compounds. Control of the sedimentation process was achieved, by predicting the solids loading rate critical point using state point analysis and stirred/unstirred settling velocity tests and by applying a high return activated sludge rate. The nitrogen gas related sedimentation problems were taken into consideration.
authors.affiliation: Environmental Chemistry and Wastewater Treatment Laboratory Environmental Engineering and Pollution Control Department, Technological Education Institute of Western Macedonia, Koila, Kozani 50100, Greece E-mail: eAmanatidou@teiwm.gr.
authors.forename: E
authors.initials: E
authors.lastname: Amanatidou
authors.affiliation: Environmental Chemistry and Wastewater Treatment Laboratory Environmental Engineering and Pollution Control Department, Technological Education Institute of Western Macedonia, Koila, Kozani 50100, Greece E-mail: eAmanatidou@teiwm.gr.
authors.forename: G
authors.initials: G
authors.lastname: Samiotis
authors.affiliation: Environmental Chemistry and Wastewater Treatment Laboratory Environmental Engineering and Pollution Control Department, Technological Education Institute of Western Macedonia, Koila, Kozani 50100, Greece E-mail: eAmanatidou@teiwm.gr.
authors.forename: E
authors.initials: E
authors.lastname: Trikoilidou
authors.affiliation: Environmental Chemistry and Wastewater Treatment Laboratory Environmental Engineering and Pollution Control Department, Technological Education Institute of Western Macedonia, Koila, Kozani 50100, Greece E-mail: eAmanatidou@teiwm.gr.
authors.forename: G
authors.initials: G
authors.lastname: Pekridis
authors.affiliation: Environmental Chemistry and Wastewater Treatment Laboratory Environmental Engineering and Pollution Control Department, Technological Education Institute of Western Macedonia, Koila, Kozani 50100, Greece E-mail: eAmanatidou@teiwm.gr.
authors.forename: L
authors.initials: L
authors.lastname: Tsikritzis
mesh_terms: D000003:Abattoirs; D018533:Biomass; D019149:Bioreactors; D007220:Industrial Waste; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry*; D014873:Water Pollutants / Q000737:chemistry*
chemical_list: D007220:Industrial Waste; D009584:Nitrogen; D012722:Sewage; D062065:Wastewater; D014873:Water Pollutants