Vertical flow constructed wetlands for septic sludge mineralization and dewatering

The accumulated sludge in septic tanks has to be treated before the adequate final disposal, because of its high concentration of non-established organic matter, elevated content of moisture and pathogenic organisms. As an alternative to the treatment of sludge, the vertical flow constructed wetlands are a promising technology. To evaluate the potential of the filters in dewatering and mineralization of septic tank sludge, two pilot-scale constructed wetlands (CW1 and CW2) were implanted according with two total solids loads (TS) - CW1: 250 kgTS.m(-2).year(-1); CW2: 125kgTS.m(-2).year(-1). The results demonstrated that the CW2 had better efficiencies compared with CW1, in terms of total solids (96%), chemical oxygen demand (99%) and ammonia (72%) removal. CW2 also provided a better dewatering, with moisture of 67% in accumulated sludge and 33% of total solids.