The competitive growth of Zoogloea ramigera and type 021N in activated sludge and pure culture ― a model for low F: M bulking

摘要: Bulking is a common problem in activated sludge plants and usually associated with excessive growth of filamentous bac teria. A variety causes have been implicated including low dissolved oxygen (DO) concentration, nutrient deficiency, high sulfide concentration (septic wastewater), organic load ing, that is, food-to-microorganism ratio (F:M). Laboratory experiments field studies illustrated creation initial wastewater substrate concentrations, or gradients, can prevent cure F:M bulking. High concentrations be created practice by intermittent feeding to the aeration basin, sequencing batch reactor (SBR),1"6 modifi cation basin configuration incorporate plug flow one more small basins (selectors) upstream main basin.4'7"18 These empirical laboratory all show cre ation spatial temporal allows system select flocculant rather than ac tivated sludge. Several hypotheses exist explain preferential selection floc-forming bacteria surface area volume theory,17 kinetic theory,9 accumulation regeneration theory,5 starvation theory.6 This paper presents experimental results why fil amentous organisms such as Type 02IN are selected com pletely-mixed systems mechanism which selectors function organism bulking at F:M. Experiments included both pure culture work on representative bacterium (Zoogloea ramigera) (Type 02IN) cause Growth uptake kinetics these two were incorpo rated into mathematical model used design predict aerobic selector performance systems.19