Rehabilitation of an available facultative pond unit using a trickling biofilter

The objective of this study was to upgrade a facultative pond (FP) unit operating at the domestic wastewater treatment plant (WWTP) in the municipal area of Sakhnin, which is located in the North of Israel (latitude 32.869155 and longitude 35.316570). For this aim, six experimental units of the intermittent trickling biofilters (ITBFs), with different design and operation characteristics, were established in April 2005 as a pilot plant system at the bank of the WWTP. The experimental units were operated under controlled conditions parallel to the full-scale FP of the WWTP for over 12 months, and the influent and effluent qualities were analyzed on a regular basis. With the ITBF units, the average removal efficiency of the system on sCOD, total suspended solids, NH₄-N, and PO₄-P reached up to 79.7, 91, 76.9, and 74.8%, while the average removal efficiencies of the same parameters in the reference FP were: 6.7, 16.3, 3.6, and 18.1%, respectively.