Estudo Da Eficiência De Reatores De Ultrafiltração No Polimento De Efluente De Lagoas De Estabilização Em Série

Abstract

In recent years in Brazil, the heat and the lack of rain were the major causes of the low level of dams, leaving some regions in alert and subject to rationing. In this sense, the use of filter membranes in sewage aftertreatment (effluent polishing) has been increasing to produce a reuse water of sufficient quality so that it can be reused in several sectors, in order to reduce the utilization of potable water from concessionaries for less noble purposes, generating savings and reducing levels of water shortage. Thus, the objective of this work was to verify the efficiency of the ultrafiltration reactors in the effluent polishing of stabilization ponds in series for the production of permeate with high purity, as well as to evaluate the possibility of reuse of the permeate for unrestricted irrigation, flushing toilets, cleaning of floors and yards, firefighting, etc. To this end, the effluent previously treated biologically in stabilization ponds in series (two anaerobic ponds in series and a secondary facultative pond), in the Sewage Treatment Plant of the Companhia de Água e Esgoto da Paraíba (CAGEPA), was filtrated on an ultrafiltration membrane, whose permeate was collected and stored for the use of the ultrafiltration pilot station (acid and alkaline washing and backwash). The effluent from the ponds and the filtration permeates were collected and sent to the laboratory for analysis of pH, conductivity, total solids, ammoniacal nitrogen, total and thermotolerant coliforms, biochemical oxygen demand (BOD), chemical oxygen demand (COD), TDS (total dissolved solids), FDS (fixed dissolved solids) and VDS (volatile dissolved solids). It was possible to conclude that the ultrafiltration membrane presented excellent efficient indexes in the removal of thermotolerant coliforms, turbidity, BOD, COD and total suspended solids. Making it possible to use its permeate as reuse water of class 1, 2, 3 and 4, according to the NBR (Norma Brasileira) 13.969 / 1997 ABNT (Agência Brasileira de Normas Técnicas), making it necessary to only add the disinfection (chlorine addition) step at the end of the ultrafiltration process, in order to ensure levels of residual chlorine compatible with those of the Brazilian norm quoted above.