Characterisation of septage in partially sealed cesspit

The alteration of wastewater from an individual home under anaerobic conditions in a partially sealed cesspit over the filling period of four months, and the pollution fluxes were assessed. The septage was much more concentrated than raw wastewater. A mass balance found percentage (%) removal rates for biological oxygen demand (BOD₅, 78%), chemical oxygen demand (COD, 62%), total nitrogen (TN, 52%), PO₄³⁻-P (67%) and total suspended solids (TSS, 69%). The percentage (%) pollution loads of emptied septage were BOD₅ (22%), COD (38%), TN (48%), PO₄³⁻-P (33%) and TSS (31%). The heavy metal content in septage was not complying with regulations for wadi disposal and effluent reuse in agriculture. Most of the TN removed, equal to 52% of the TN load to the cesspit, will most likely have infiltrated into the surrounding soil, and might reach the groundwater. Therefore, cesspits that are widely applied should be urgently replaced by proper on-site or off-site wastewater management systems.