N Mokhtarani - Deartment ofCivil Engineering, Tarbiat Modares University, P.O.Box ۱۴۱۵۵-۱۴۳, Tehran, Iran
A Bayatfard - Jahesh Kimia Co., P.O.Box ۱۳۴۴۵-۱۳۸۱, Tehran, Iran
B Mokhtarani - Chemistry & Chemical Engineering Research Center of Iran, P.O.Box ۱۴۳۳۵-۱۸۶, Tehran, Iran

A very wide range of treatment processes have been applied to leachate treatment with varying success. The aim of this research was to examine the performance of two anaerobic biological filters in a new full scale leachate treatment plant in Rasht composting facility, north of Iran. The studied plant was operated during nearly 12 month and treats up to 50 m3/d of fresh compost leachate. The average COD and BOD5 of raw leachate was measured to be 81000 and 39000 mg/l respectively. 30% of effective volume of each reactor was filled with the clay blocks with specific area of 87 m2/m3asthe fixed bed. The sequencing of reactors was down flow and up flow respectively. Removal of COD was in average 85% and of BOD5approx. 89% indicating good degradation of biodegradable organic matter. The maximum COD removal efficiency of 91% was achieved with 4.5 kgCOD/m3.d of organic loading rate and 7500 mg/.l of VSS. There was no significant difference in COD removal efficiency when the reactors were operated with organic load between 2 and 5 kg COD/m3.d.Increasing of volumetric organic loading rate above 6 kg COD/m3.d caused considerable reduction of COD removal efficiency. COD removal efficiency reached to less than 70% when organic load rising to 10.8 kg COD/m3.d. Nevertheless, biological filter proved to be a feasible technique for the treatment of the composting leachate under study, and it can be considered as a suitable treatment for this type of wastewaters.

Anaerobic Filter, Composting, Fixed Bed, Leachate Treatment