Otimização tecnológica de estações de tratamento biológico (ETB) de águas residuárias de coqueria

Abstract

The treatment of effluents in a coke industry occurs generally by activated sludge process. The operation and efficiency of the process depends on a large number of factors including chemical composition, quantity of the effluents, mass and composition of the activated sludge, environmental temperature, precipitation, solar radiation, dissolved oxygen, and homogeneity of the liquid system. Many times, the operational control of this system is done by chemical, physical-chemical and microbiological analysis. Even with daily control, the influents and the effluents of the biological treatment system show significant variations from the observed values. The present study has the objective to optimize analytically and technically activated sludge process. Inicially parameters like pH, OD, ORP, N-NH4, N-NO3 were determined in order to verify the efficiency of the aerators which transfer oxygen to the environment andmaintain the sludge in suspension. Some methods were also developed to measure the influence of toxic substances on the specific activity of certain microorganisms, specifically the nitrifiers and the ones degrading the organic compounds. The methodology is based on the rapid consumption of Dissolved Oxygen (DO) when an ammonium chloride solution is mixed with nitrifying organisms. It was observed that asubstrate coming from the process would inhibit the nitrification process when the concentration of the affluent is significant. With the same technique the specific activity of the microorganisms degrading the acetic acid was measured. Also the biological sludge profile was determined with the identification of regions of inhibition. These regions were found to be in the first zone precisely at the entrance of the sludge reactor.Based on these observations process improvements were proposed.