Low-rate trickling filter effluent: characterisation and crossflow filtration

The low-rate trickling filter is the most common biological treatment process used in small and medium sized sewage works in the UK. It produces an inconsistent effluent quality, which has traditionally been related to seasonal changes in solids accumulation, grazing activity and sloughing of microbial film. The final effluent solids and, organic matter content is then too high for discharge or reuse. Given the increasingly stringent effluent standards, both in terms of quality and consistency, tertiary treatment is often required. This study was designed to investigate the key parameters affecting the performance of low-rate trickling filters and the characteristics of their effluents in terms of contaminant size, which might influence the efficiency of crossflow filtration as a tertiary treatment for the trickling filter. [Continues.]