Investigação de processos operacionais de uma estação de tratamento de água de ciclo completo

Abstract

In Brazil, complete cycle complete treatment plants are present in most municipalities as an alternative treatment of water for different types of raw water. However, as the basin becomes more urbanized, supply sources suffer from environmental impacts, deteriorate in quality, and become a challenge for drinking water suppliers to meet drinking standards. Therefore, it is necessary that the operational processes of the water treatment plants (ETAs) adapt to the current reality so that the standards established by Annex XX of the Consolidation Ordinance No. 5 of 2017 are satisfied and also that the waste generated in the process are treated, released in the environment with minimal impacts. In this context, the purpose of this study is to perform an evaluation of the performance of a complete cycle ETA, located in the city of Maceió-AL, investigating the quality of raw water, its unit operations, the quality of treated water and waste generated. Quality analyzes of raw and treated water were carried out, considering compliance with current legislation, data collection of hydraulic parameters of design and operation; coagulation assays, and characterization of the liquid waste generated. The results showed that annual mean values show that the Pratagy spring does not fit into CONAMA Resolution 357/05 for Class II sweet water bodies, that the quick mixing and flocculation and filtration unit are no longer functioning as designed and out of the parameters of NBR 12.216 / 92, causing deficiencies in the functioning of the unit processes, but that even then ETA produces water within the standards of potability, outside the recommended. The aluminum sulphate showed formation of the flakes in the optimum region with 55 to 67.5 mg / L of coagulant dosages between pH 6.5 and 6.77, indicating more satisfactory removal values than the PAC. The two decanters operate homogeneously in the production of residues and the values obtained in the physico-chemical composition of the residues indicate that the treatment plant does not fit into CONAMA Resolution 430/2011 for effluent releases. Nevertheless, in spite of several disagreements between optimal parameters, design and actual operation, besides the systematic failure in the operation in the treatment stages, the complete cycle ETA is able to present satisfactory performance as the quality of the treated water.