Cinética de nitrificação e desnitrificação em sistemas de lodo ativado.

Abstract

To design wastewater treavtment systems with nitrogen removal by denitrification, it is necessary to determine the laws that rule the kinetics of this process. From the literature, it is knovn that there are several factores influencing denitrification kinetics the roost important ones being the composition of the influent organic material, temperature and sludge age. In this work the rates of nitrification and denitrif ication in an activated sludge process are determined experimentally and interpreted in terms of the general theory of van Haandel, Ekama and Marais. The utilized method involves the operation of a completely mixed activated sludge system constructed at bench scale and operated under steady state conditions of organic and hydraulic load, and with intermittent aeration: during the periods of aeration there i s production of the nitrate ion due to nitrification, during the periods when there i s no aeration (anoxic periods) denitrification o.cçujrs, , The rates of nitrification and denitrification are determined from the variaton of the nitrate concentration during the aerobic and anoxic periods respectively. Thus it is possible to determine the kinetic constant that allow to design rationally activated sludge processes with denitrification. The experimental investigation was carried out from June to October 1983 in the Sanitary Engjjieering laboratory of the Federal University of Paraíba - Campina Grande - Brazil, with temperatures ranging from 20 t o 28°C, the range of temperatures that prevails in wastewater treatment systeins in Brazil. Apart from the temperature, during the investigation the following parameters were varied: influent flow rate, sludge age, concentration of the influent organic material and aerobic and anoxic periods.