Performance and bacterial community composition of volcanic scoria particles (VSP) in a biological aerated filter...

A laboratory-scale biological aerated filter (BAF), using volcanic scoria particles (VSP), was used for treating micro-polluted source water. The system reached a steady-state stage and performed better at removing pollutants. In steady-state stage, the effluent ammonia ( $$ ) and chemical oxygen demand (COD) were consistently maintained below 0.3 and 3 mg/L, respectively. Both the $$ and COD removal efficiencies decreased with shorter hydraulic retention time (HRT). The effluent $$ and COD exceeded health standards at 15 min of HRT. Although performance was relatively poor for VSP-BAF at low temperature, the $$ removal still achieved the drinking water quality standard. The influences of influent $$ and COD concentration changes were similar to that of temperature. A better performance was observed in $$ removal under higher influent $$ concentrations. In contrast, the effluent COD was more than 3 mg/L when the influent COD concentrations increased to about 9 mg/L. The phylogenetic and cluster analyses indicated that the effect of HRT on bacteria community structure was higher than that of temperature, while the ammonia-oxidizing bacteria (AOB) are sensitive to temperature. The main phyla identified in total bacteria communities were Proteobacteria, Bacteroidetes, Firmicutes, and Nitrospirae. The main AOB were Nitrosomonadales and an uncultured ammonia-oxidizing bacterium. PRACTITIONER POINTS: The BAF using VSP obtained a good performance for treating micro-polluted source water. The influence of HRT on the system was more significant than that of temperature. The system is resistant to $$ concentration shocks while is unable to withstand the COD increasing. The effect of HRT on bacteria community structure was significantly higher than that of temperature.