A study of the impacts of periodic ozone residuals on biologically active filters

The research presented in this article investigated the effects of ozone residuals on the biological performance of a biologically active anthracite/sand filter. In addition, the impact of residuals of hydrogen peroxide (H2O2), added as an accelerator of natural ozone decay, was investigated. Experiments were performed at laboratory scale using four parallel filter columns. The periodic presence of O-3 (1-2 hours per week) at concentrations of 0.1-0.2 mg/L in the influent of an anthracite/sand filter had a negligible effect on the biological removals of acetate and formate. This was likely the result of the observed rapid decrease of the O-3 concentration in the top part of the filter. The periodic presence (1-2 hours per week) of H2O2 (similar to 0.5 mg/L) in the influent of an anthracite/sand filter had no measurable effect on biological acetate and formate removals.