Temperature-Dependent Formaldehyde Degradation in Trickling Filters

Abstract

We investigated formaldehyde (HCHO) degradation in a trickling filter at three different temperatures. Formalin, equivalent to an initial concentration of 40 mg of formaldehyde per liter of water, was applied to a closed experimental setup that included an active trickling filter. Water samples were taken regularly over a 96-h period and analyzed for formaldehyde. Decomposition of HCHO was significantly related to water temperature; estimated half-lives were 5.0, 9.5, and 16.5 h at 14.5, 10.0, and 5.5°C, respectively. Evidence of microbial decomposition indicated that formaldehyde reduction was correlated to the available trickling-filter surface area at a removal rate of 8.3–21.3 mg formaldehyde·m⁻²·h⁻¹. These findings permit the calculation of formaldehyde decomposition rates during treatments in recirculating systems and make it possible to design trickling filters with a specific decomposition capacity.