Automação de um sistema de tratamento de esgotos baseado no processo de lodo ativado.

Abstract

In this dissertation, a wastewater treatriient system is presented. K. consists of an anaerobic process, accomplished by an UASB reactor, in series with an aerobic process, iiiiplemeiited by asequencing batcli reactor. The UASB reactor was cliosen as the anaerobic process because it's a system of great potenfial for áreas of hot cliniafe, as the Northeast arca. The sequencing batcli reactor was used as aerobic process since it is the simplest version of the activated sludgc systeins. The use of a lrybrid system, that is, an anaerobicaerobic one, seeks the reduction of the construction and operation costs of the treatment plant. In this case, great part of the wastewater organic material is removed in the anaerobic process, so that, the aeration tanks and the amount of oxygen needed for the aerobic stage are smaller. The automation of this treatment system was iniplemented. As the anaerobic process doesn't use electric nor mechanical equipments, the automation isjust limited to the aerobic process, that is, to the sequencing batch reactors. It is possible to operate the system automatically, or remotely through a computer running a supervisory system. Besides the automation, a new technique for determing the end of the aeration period was presented in this dissertation. This technique, difFerently from the classic techniques, has no need to estimate parameters as the respiration rate or the oxygen transfer function. In this case, the average value of the oxygen dissolved concentration in the reactor indicates when the aeration should be interrupted. Then, with this technique, the system is capable to treat a larger wastewater volume by day, besides saving energy.