Septage composition and pollution fluxes from cesspits in Palestine

Abstract

The cesspit septage quality and pollution loads of total nitrogen (TN) and heavy metals (HMs) from 50 cesspits were assessed during various filling periods. The average specific wastewater production, emptied septage and infiltrated septage were 49, 30 and 19 L/c d, respectively. The TN specific loads of septage fractions that were emptied and infiltrated were 8.5 and 3.3 g/c d, respectively. The concentrations of HMs (mg/L) in the septage were Cu (0.24), Ni (0.03), Pb (0.01), Mn (0.47), Fe (12.6), Cr (0.04) and Zn (1.23). The septage content of Cu, Mn and Fe did not comply with the Palestinian regulations for wadi disposal nor effluent reuse in agriculture. The specific TNinfiltration from cesspits amounts to 29 kg TN/ha y. There was no relation between the HM and TN content of septage and the desludging frequency. The infiltrated septage contributed to as much as 15% of the total groundwater recharge in the study area. This study confirms that cesspits in Palestine should be replaced with proper wastewater management systems for adequate environmental protection.