Effectiveness of Natural Zeolite and Geo-fabric as Single and Dual Media in Biologically Aerated Filters (BAFs) for Greywater Treatment

The performance of a dual-media biologically aerated filter (NZGF-BAF) incorporating natural zeolite and geo-fabric was studied and compared with single-media BAF systems using only natural zeolite (NZ-BAF) or geo-fabric (GF-BAF) in batch mode. The study examined how hydraulic retention time (HRT), carbon-to-nitrogen (C/N) ratio, aeration rate, and filter depth affected the removal of contaminants such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia-nitrogen (NH3-N), turbidity, and total dissolved solids (TDS). Results showed that under similar conditions, NZ-BAF and GF-BAF performed similarly in removing COD, BOD, and turbidity, thanks to their larger surface areas, biofilm development, and absorption and adsorption capacities. NZ-BAF was more effective at removing NH3-N due to its ion-exchange properties, while GF-BAF excelled in TDS removal through permeability, adsorption, and bacterial activity. The dual-media NZGFBAF demonstrated improved removal efficiencies across all contaminants. An optimization study using Response Surface Methodology (RSM) under optimal conditions revealed maximum removal rates of 93% for COD, 98% for BOD, 94% for NH3-N, 93% for turbidity, and 67% for TDS.