title: Nocardia foaming control in activated sludge process treating domestic wastewater.
abstract: In this study, filamentous bacteria (Nocardia amarae) were identified as the major causal microorganism in foaming sludge. The results of growth kinetics study indicated that N. amarae had a relatively strong affinity for non-readily biodegradable fatty acids. N. amarae was able to consume various fatty acids at a constant growth yield from 0.413 to 0.487 g/gCOD. Under common F/M ratio (less than 0.5 g BOD/gMLSS/d) used in activated sludge processes, specific growth rate of N. amarae was found to be more significant than that of non-filamentous bacteria. Based on this feature, a novel technique feast-fast operation (FFO) was developed for the foaming control. The sludge volume index (SVI) rapidly decreased from 300 to 80 mL/g and further stabilized at about 70 mL/g and the system was free from stable foam, while the BOD removal efficiency was maintained above 95%. This control technology effectively suppressed the overgrowth of filaments and improved the settleability of activated sludge without adverse effects on the treatment performance and the process stability.
authors: Department of Civil and Structural Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. chris.tsangyf@yahoo.com.hk
authors: Y F
authors: YF
authors: Tsang
authors: S N
authors: SN
authors: Sin
authors: H
authors: H
authors: Chua
mesh_terms: D002244:Carbon / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D007700:Kinetics; D009615:Nocardia / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D010100:Oxygen / Q000302:isolation & purification; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development; D012722:Sewage / Q000382:microbiology*; D018508:Water Purification / Q000379:methods*
chemical_list: D005227:Fatty Acids; D012722:Sewage; D002244:Carbon; D010100:Oxygen