Perdas de carga em filtros rápidos de fluxo ascendente e descendente

Abstract

The following study of the head loss in filters, whether of upstream or downstream flow, is of main importance in the projection and mainly in the operational control of such units in a water treatment plant (WTP). However, its mathematical prediction modeling is still relatively unsatisfactory due to the different intrinsic variables in the filtration efficiency process, such as filtration mechanisms, previous treatment processes, filtration rate and, above all, composition and grain size filter media. This paper presents the study of the charge losses in double filtration treatability tests carried out in a pilot dual filtration system (PDFS), in order to evaluate the influence of the granulometry of the filter layers on the upstream and downstream filters and applied rates in the variation of laminar and turbulent head loss with the retention of impurities that is interpreted in the turbidity. It were performed four 24-hour duration tests, which were tested one upstream filter gravel (UFG) and then three quick sand downflow filters (SDF) with varying particle sizes to each other, preceded by pre-oxidation and coagulation, with variation of filtration rates of 230 and 255 m³ / m².day and 310 and 340 m³ / m².day, respectively. The results of the PDFS samples show that the UFG had great efficiency in the removal of turbidity with loss of load influenced by the false bottom, since the SDF evidence that the lower the granulometry of the filters, the greater the efficiency of removal of impurities, loss of load and less filtration career. The SDF 3 was chosen because of operational issues, as the remaining turbidities of the SDF were close. Closing the following paper, the increase of the applied filtration rates conferred increase of the loss of load and decreases of the removal of impurities and filtering career.