Determinación de las condiciones de oxigeno disuelto de un sistema de lodos activados que permita la producción de lodos fácilmente biodegradables con alto contenido de phb

Abstract

One of the problems of activated sludge systems is the great amount of sludge they produce, which is usually stabilized by anaerobic digestion and later disposed off in sanitary landfills. Different sludge pretreatment methods and operational variables have been tested with the purpose of accelerating its anaerobic digestion. It has been proved that energy storage compounds as polyhydroxybutyrates (PHB) are rapidly degraded in anaerobic reactors. If the balance in the conversion of the organic matter in the biological oxidation tank of activated sludge were controlled to promote the formation of biomass with high PHB content, it would be possible to accelerate the anaerobic digestion of the sludge generated, and to maintain high levels of organic matter removal. This project studied the effect of three concentrations of dissolved oxygen (2 mg/L, 2.5 mg/L and 8 mg/L) on the accumulation of PHB in heterotrophic bacteria and the level of conversion of the organic matter in a laboratory‐scale activated sludge system, fed by synthetic domestic wastewater, at an organic loading rate of 1 kg COD/m3∙d at room temperature. The findings indicated that the lower the dissolved oxygen concentration, the higher the PHB accumulation, resulting in a PHB content of 2.28 mg/g VSS at 2 mg/L of dissolved oxygen in the sludge and good COD removal efficiency.