Growth kinetics of the filamentous microorganism Sphaerotilus natans ATCC # 29329 in a model system of a food industry wastewater.

CONTRERAS E. M, GIANNUZZI L AND ZARITZKY N. E.

WATER RESEARCH

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2000 vol. 34 p. 4455 - 4463

0043-1354

Bulking by Sphaerotilus natans has been attributed to several factors such as low dissolvedoxygen in the aeration basin, wastes with high C:N ratios and phosphorus limitation; however, theoccurrence of bulking has been reported in fruit, vegetable, meat and poultry wastewaters in which the ratio C:N is variable. Growth of S. natans was analyzed in a model system of a food industry wastewater (potato processing waste) that was characterized by HPLC determining that citric acid was the most important identified component. The e€ffect of several carbon sources on S. natans growth was also studied; different C:N ratios were tested in a continuous culture system (chemostat). This strain grew in a mineral medium with citric acid as a sole carbon source, in spite of the contradictory results found in literature. Chemostat studies showed that the medium was carbon-limited when C:N ratios <19 mgCOD (mgN-NH3)-1. Monod kinetic growth coecients, determined for this strain in chemostat were: maximum specific growth rate, mu max=0.301 h-11; Monod constant, KS=4.6 mgCOD l-1,  true biomass growth yield, YTX/S=0.490 mgVSS mgCOD)-1;  endogenous decay rate, kd=0.011 h-1 and maintenance coeficient, mS=0.022 mgCOD (mgVSS)-1h-1. The obtained parameters were compared with literature data and the e€ffect of glucose and citric acid as carbon sources was discussed; these parameters are useful in modeling the growth of S. natans in potato processing wastewaters (or in other effl‚uents under carbon-limiting conditions) especially when citrate is the main component and can be used to control filamentous bulking by metabolic or kinetic selection.