| Activated sludge floc characteristics, filamentous bacteria and their abundance were observed in direct light (magnification 125x, 250x), in phase contrast (1250x) and after Gram and Neisser staining (1250x). Sludge volume index (characterization of good/bad settling properties) was measured in all samples of activated sludge. The most common filaments in activated mixed liquor were M. parvicella, N. limicola (Pict. 3) and Types 0092 and 0041/0675 while the biological foams were dominated by M. parvicella (Pict. 1) and nocardioform actinomycetes (Pict. 2). The most frequent sludge volume index belonged to the category "light" (= 100-200 ml/g). Mathematical models (e.g. ASM No. 1, IAWPRC, UCT) are used for design of new WWTP´s, for optimization of existing WWTP´s or on-line control of WWTP´s. The following recommendations for control of bulking and foaming resulted from the project: use of compartmentalized contact zones, regeneration of return activated sludg, use of baffles protecting the effluent weirs in secondary clarifiers. Key contacts: Prof. Jirí Wanner, M.Sc., D.Sc., ICT Prague, Dept. of Water Technology and Environmental Engineering, Technická 5, CZ-166 28 Prague, Phone + 420 2 24 35 31 49, fax + 420 2 24 31 07 70, E-mail jiri.wanner@vscht.cz, Iveta Ruzicková, M.Sc., ICT Prague, Dept. of Water Technology and Environmental Engineering, Technická 5, CZ-166 28 Prague, Phone + 420 2 24 35 31 50, fax + 420 2 24 31 07 70, E-mail iveta.ruzickova@vscht.cz, Olga Krhutková, M.Sc., ICT Prague, Dept. of Water Technology and Environmental Engineering, Technická 5, CZ-166 28 Prague, Phone + 420 2 24 35 31 50, fax + 420 2 24 31 07 70, E-mail olga.krhutkova@vscht.cz |
