Avaliação da eficiência do leito de secagem no processo de desidratação de lodo gerado nos decantadores da estação de tratamento de água

Abstract

During the water treatment process residues are generated among them the sludge, which, in most stations, are not treated and are returned directly to the well, negatively impacting it. This work presents the use of a conventional drying bed as a preliminary treatment for the residues generated in the Formiga – MG ETA decanter in order to reduce the impact caused by its direct release to the receiving bodies. For this, the research consisted of the following steps: i) to qualify the periods (dry and rainy) in the attributes of raw water and in the generation of sludge; ii) construction of a conventional drying bed; iii) collection, sludge characterization, and monitoring of the sludge dehydration process; iv) biological physico-chemical characterization of the percolate generated in the sludge dewatering process, together with the maximum values allowed by CONAMA Resolution 430/11. The results of the characterization of the crude sludge indicated that it does not meet the standards for effluent releases. The drying bed was shown to be an excellent mechanism of dewatering of the sludge, leaving the same, in both periods of the research, under appropriate conditions for transporting the sludge. On the other hand, the analysis of the percolate generated in the dehydration process indicated that the residual aluminum of the aluminum sulfate dosage was retained in the drying bed. The other parameters, such as iron, turbidity, color, BOD and total solids, were significantly reduced, staying within the parameters allowed by CONAMA Resolution No. 430/2011. In a simple dehydration of the sludge have excellent results.