Influence of the geotextile blanket and sludge height in anaerobic sludge dewatering using drainage bed

ABSTRACT Sewage Treatment Plants generate sewage sludge, which has approximately 95% of water and requires a proper disposal. Thus, dewatering is fundamental in sludge’s management since it promotes volume reduction of the residue. The drainage bed (DB) is a natural system, without the use of energy and chemicals, with prosperous results for the dewatering of sludge from Water Treatment Plants. In this sense, this research aimed to evaluate sewage sludge’s dewatering from Upflow Anaerobic Sludge Blanket (UASB). The analysis was performed through nine tests in DB models from laboratory scale with a bottom area of 31 × 31 cm. The tests were performed with three different geotextiles blankets: HaTe 55/55; 80/80 and 105/105 DW and three heights of applied crude sludge: 10, 15 and 20 cm. In the tests, the crude sludge’s initial solid content was measured. Then, at predetermined time intervals were measured: drainage flow, drained volume, apparent color, turbidity, pH and drained liquid’s conductivity. The tests with the HaTe 55/55 geotextile blanket obtained the best performance, with final reduction of the sludge volume above 65%, independent of the height of the sludge applied. The color and turbidity results of the drained liquid for the HaTe 55/55 geotextile blanket showed a tendency to improve quality with the increase of the sludge height, a fact not observed for the other geotextiles blankets.