Use of biofilter units to enhance the effluent quality of anaerobically pretreated domestic wastewater.

Abstract

This study evaluates the use of a pilot plant biofilter system which is comprised of an Anaerobic Filter (AF) followed by a passive aerated Rapid Filter (RF), as a post-treatment option for Birzeit domestic wastewater. It reports on the biofilters efficacy for the removal of organic matter and nutrient removal during three different run phases. The biofilters were fed continuously with a variable daily flow rate (0.26-0.6 m3) to study the impact of different Organic Loading Rates (OLRs) and Hydraulic Retention Times (HRTs). During the run phases 1, 2 and 3, the average removal efficiency of the biofilters (AF+RF) for COD was 28, 65 and 30%, respectively. The complete treatment chain achieved a removal efficiency of 54, 51 and 43% for suspended solids at variable OLR and HRT. At higher HRTs, the RF average removal efficiency for NH4 reached only 8%. This research suggested an organic loading rate of 10 g COD/ (m2.d) for the AF to achieve an effluent quality by the RF suitable for restricted agricultural irrigation. Further large-scale studies should locally be carried out to improve and validate the onsite treatment system used in this research paper.