Bench-scale determination of the removal of odour compounds with biological treatment

A bench-scale bioreactor was designed to determine the parameters required for kinetic modelling of assimilable organic carbon (AOC) removal. This reactor was then used to attempt to determine the kinetic parameters in modelling the removal of two odorous compounds, (geosmin and 2,4,6-trichloroanisole) with biological treatment. The bench-scale bioreactor column had a volume of 56 ml, contained 2540 × 3 mm glass beads, and was operated at a feed rate (Q) of at least 2.0 ml/min with a recycle rate (Qr) of 50-70 ml/min. At these rates the bioreactor can be regarded as a continuous stirred tank reactor (CSTR). The biofilm was established using filtered river water blended with an acetate solution and was maintained with an inorganic nutrient and buffer solution. A synthetic water containing geosmin and 2,4,6-trichloroanisole (2,4,6-TCA) was fed to the column after the biofilm had reached steady state. Influent concentrations and effluent concentrations were monitored using extraction with a closed-loop stripping apparatus (CLSA) and analyses using gas chromatography-mass spectrometry (GC-MS). The bioreactor did not effectively remove the taste and odour compounds being studied and these poor removals prevented determination of kinetic parameters. A bioreactor which is not acclimated and which receives an organic and hydraulic loading in the range normally experienced by rapid filters and granular activated carbon (GAC) contactors could not be recommended as a primary treatment process for the removal of these taste and odour compounds.