Modelado del efecto del cloro sobre microorganismos floculantes y filamentosos provenientes de barros activados

CARAVELLI A. H.; CONTRERAS E. M.; GIANNUZZI L.; ZARITZKY N. E.

Valencia, España

Congreso; III Congreso Iberoamericano de Ingeniería de Alimentos y I Congreso Español de Ingeniería de Alimentos; 2001

Instituto de Ingeniería de Alimentos para el Desarrollo

Activated sludge reactors are commonly used for the biological treatment of industrial food wastes. Chlorination is the most economical, non-specific method for controlling the excessive growth of filamentous microorganisms causing bulking in activated sludge systems. Considering that chlorination affects both floc-forming and filamentous microorganisms, it is necessary to define the adequate doses to control bulking, minimizing the effect on floc-forming bacteria. Respirometry is a method widely used to evaluate the toxicant effect of different compounds. The objectives of the present work were: a) to evaluate the effect of chlorine in pure cultures of a filamentous microorganism (Sphaerotilus natans ATCC #29329) and a floc-forming bacteria (Acinetobacter anitratus) using respirometric technique to determine the specific sensivity of both microorganisms b) modelling chlorine decay at different biomass concentration. The culture medium contained citrate as the limiting carbon and ammonia as nitrogen source. Pure culture experiments were performed in a chemostat under continuous flow conditions; the temperature was 30 ± 0.2 ºC, pH = 7.0 and aeration was enough to maintain dissolved oxygen concentration above 2 mgO2 l-1. Tested dilution rates ranged between 0.07 h-1 and 0.43 h-1. All inactivation studies were conducted at 30 ºC in a respirometer. The samples were treated with sodium hypochlorite ranging between 2.5 to 18 mgCl2/gSSV in a batch system. The decay of chlorine corresponded to a global second order kinetic equation and a satisfactory agreement between experimental data and the proposed model was observed. Using respirometry, the inhibition indices for both microorganisms were determined; the floc-forming microorganism were more sensitive to the assayed doses of chlorine.