title: Net biomass production under complete solids retention in high organic load activated sludge process.
abstract: The effect of complete solids retention on net biomass production, at a slaughterhouse's activated sludge wastewater treatment process, was studied for 425 days. The process reached equilibrium after 150 days. In equilibrium phase, and until the end of the study, relative constant MLVSS to MLSS ratio, low food to microorganisms ratio (F/M), low substrate utilization rate (SUR) and negligible observed sludge yield (Y obs) were measured. Y obs fluctuated between positive and negative values (± 0.03 gVSS gCOD(-1)), tending zero mean values, and leading to the conclusion that zero net sludge growth can be achieved. The high BOD ultimate/COD ratio and the zero sludge accumulation, leads to the conclusion that all fractions of organic matter, including cell debris, are biodegradable. The results were verified by comparing the measured Y obs values and those predicted using a conventional activated sludge model (ASM) and a modified ASM that incorporates the slow hydrolysis concept of the unbiodegradable compounds.
authors.affiliation: Laboratory of Environmental Chemistry and Wastewater Treatment, Department of Environmental Engineering and Pollution Control, Technological Education Institution of Western Macedonia, Greece. Electronic address: eamanatidou@teikoz.gr.
authors.forename: Elisavet
authors.initials: E
authors.lastname: Amanatidou
authors.affiliation: Laboratory of Environmental Chemistry and Wastewater Treatment, Department of Environmental Engineering and Pollution Control, Technological Education Institution of Western Macedonia, Greece. Electronic address: waterlab2@teikoz.gr.
authors.forename: Georgios
authors.initials: G
authors.lastname: Samiotis
authors.affiliation: Laboratory of Environmental Chemistry and Wastewater Treatment, Department of Environmental Engineering and Pollution Control, Technological Education Institution of Western Macedonia, Greece. Electronic address: waterlab@teikoz.gr.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Bellos
authors.affiliation: Laboratory of Environmental Chemistry and Wastewater Treatment, Department of Environmental Engineering and Pollution Control, Technological Education Institution of Western Macedonia, Greece. Electronic address: envchem3@teikoz.gr.
authors.forename: George
authors.initials: G
authors.lastname: Pekridis
authors.affiliation: Laboratory of Environmental Chemistry and Wastewater Treatment, Department of Environmental Engineering and Pollution Control, Technological Education Institution of Western Macedonia, Greece. Electronic address: waterlab3@teikoz.gr.
authors.forename: Eleni
authors.initials: E
authors.lastname: Trikoilidou
mesh_terms: D000003:Abattoirs; D057919:Biological Oxygen Demand Analysis; D018533:Biomass; D008962:Models, Theoretical; D012722:Sewage / Q000032:analysis / Q000737:chemistry; D013997:Time Factors; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*
chemical_list: D012722:Sewage
keywords: Activated sludge; Complete solids retention; Observed biomass yield; Unbiodegradable organic compounds degradation; Zero net biomass growth