EVALUATION OF A DRAINAGE BED SYSTEM IN THE DEWATERING OF SLUDGE FROM A WATER TREATMENT PLANT EFFECTED BY EXTERNAL AGENTS ON THE DRYING STAGE

Abstract

The aim of this work was to evaluate the performance of the System Draining Beds sludge dewatering in a Water Treatment Plant. Phase's drainage and drying of the sludge were evaluated, and the drying phase assays were conducted in duplicate for investigation of the influence of climatic factors on the drying time. Both experiments with three Draining Beds, each with a different geotextile, evaluated under the application of three different application rates of solids, were conducted. Once chosen the best application rate of solids, trials were conducted in which the partial influence of external agents was assessed only at the stage of drying, removing the lateral protection of the beds. Therefore, there were evaluated three geotextile blankets trials in duplicate considering partial or none influence of climatic agents. Then, for each bed studied, two blanket drain were assembled, one with side protection and other without side protection, totaling six beds of drainage. The steps of draining and drying of the sludge were evaluated at application rates of 1.75 kg∙m-2, 3.5 kg∙m-2 and 7.0 kg∙m-2 of solids. In a drain phase, the parameter turbidity was evaluated and in the drying step the influence of climate variables were observed in the dewatering of sludge to the obtained solids. It is noteworthy that the Draining Beds were protected from direct impact of rain, i.e., the influence was indirect. The effluent drained presented, earlier in the system operation, turbidity below 10 NTU and, at the end, turbidity near 1 NTU and the sludge solids showed 50% greater for the LD without lateral protection. Keywords: Water Treatment Plants (WTP), Geotextiles, Sludge, System Draining beds.