Tratamento de lodo primário de estação de tratamento de efluentes e aplicação de protocolo de avaliação.

Abstract

The primary sludge resulting from sewage treatment station of tannery is categorized according to the standard 10.004 of the Brazilian Association of Technical Standards, as Class I, or dangerous, posing a problem for companies, as to their management. Currently, the sludge has been launched in rivers or buried in soil and deposited in the courtyards of industries, consisting in an environmental liability. The purpose of this work was to realize the processing of the sludge and assess the material resulting from the stabilization/solidification by applying the specific protocol for evaluation this process. This work was done in the laboratory for environmental management and waste treatment, belonging to the Academic Unit of Chemical Engineering, of the Federal University of Campina Grande. The research comprised the following steps: First, was the planning of the experiment, which was used factorial 22 with three central points. The factors used in the study were the time and percentage of mud. The levels of the factor time were 7, 14 and 28 days and for the factor of sludge percentage were adopted levels 5, 25 and 45%. In this step was proposed the optimization process of expanding and reproducing the best results. In The second stage was performed the statistical analysis of data through the analysis of variance, to decide with some level of confidence, if the effects are significantly different, through their interaction and curvature. The third phase involved the characterization of materials (sludge and mortar of cement), through the tests of moisture content, total solids, fixed and volatile, lixiviation and solubilization of heavy metals and preparation of bodies-of-proof. The fourth stage was held to assess the stability of the materials submitted by solidification. With this work we can conclude that the time factor and percentage of sludge primary influence on the integrity /durability and detention of contaminants. The result was better for low quantity of sludge and greater time to cure the resultant material, that is, 2,5 and 5% of sludge and 28 days, representing, respectively, 97,79% and 86,58% efficiency of reduction of chromium. With the implementation of the Protocol was possible to classify and identify the routes for disposal and use of the material end. In this case, treatment with 2,5% of sludge was not known as dangerous and stabilized by solidifying with restraint, while the treatment with 5% was called solidified with restriction being able to be prepared in a special cell landfill industry.