Dewatering of septic tank sludge in alternative sludge drying bed

In dewatering of septic tank sludge, the sludge drying bed is one of the main techniques used, but it demands a great deal of area and time for the removal of sludge cake. Modification of this system using permeable pavements and polymer can minimize such problems, facilitating the management of sludge when decentralized sanitation is used. Therefore, the objective of this study was to compare the dewatering of septic tank sludge using conventional sludge drying bed (CSDB) and a sludge drying bed with permeable pavement (SDBPP). At the same time of dewatering, the volume drained by the SDBPP was 37.4 ± 4.6% higher than that obtained in the CSDB. Therefore, a lower drying bed could be used. It was found that the use of synthetic polymer allowed dewatering to occur in less time, but did not interfere in the solids content of the sludge cake. The reuse of the pavement was proven possible, but required large volumes of water and mechanical equipment.