Pilot-scale comparative evaluation of the filtration performance of dual-media filters

Abstract Filtration is a critical process in drinking water treatment, with dual-media filters widely recognised for their superior performance compared to single-medium filters. However, comprehensive comparative studies evaluating different media combinations remain limited. This pilot-scale study systematically assessed the filtration performance of four dual-media filters: anthracite–quartz sand (AQ), anthracite–garnet (AG), ceramsite–quartz sand (CQ) and ceramsite–garnet (CG). By monitoring key indicators including turbidity, particle count, UV 254 , head loss and pollutant retention capacity, the study revealed that ceramsite-based filters (CQ and CG) perform considerably better than anthracite-based filters (AQ and AG). Specifically, the CQ filter showed 18%–54% higher pollutant retention capacity, 21%–28% slower head loss growth rate and substantially longer filtration cycles. Both Rank sum ratio and JP evaluation methods consistently showed that CQ is the optimal media combination, followed by CG. The results indicate that greater differences in physical characteristics between upper and lower media layers promote better utilisation of the capacity of the filter bed. These findings provide valuable theoretical insights and practical guidance for optimising media selection in dual-media filters and inform the upgrading of single-medium filters.