Combined Carbonaceous Removal and Nitrification with Biological Aerated Filters

摘要

This paper describes the use of a submerged biological aerated filter (BAFs), on a pilot plant scale, in the secondary nitrification of low strength domestic waste-water. The results, obtained throughout three months of tests, confirmed the ability of BAFs to obtain simultaneous carbonaceous removal and nitrification. In fact, after a start-up period of 5 weeks, a remarkable steady state condition in the removal of suspended solids (TSS), chemical oxygen demand (COD) and nitrification was reached. For a hydraulic loading rate of 1.6 m~3m~(-2)h~(-1), the mean efficiency of the process in the removal of TSS and COD was 85% and 83% respectively. Mean concentrations in the influent flow of around 114 mg_(TSS)/L and 140 mg_(COD)/L were reduced to average values of below 17 mg_(TSS)/L and 25 mg_(COD)/L. Secondary nitrification was achieved with a mean efficiency of 85%) for a mean volumetric loads of 0.45 kg_(N-Namm) m~(-3) d~(-1) (25℃). Through an intensive activity of nitrification, in the steady state condition, mean influent concentrations of around 12 mg_(N-Namm)/L were reduced to average values of below 2 mg_(N-Namm)/L. The removal loading rate increased linearly with the applied loading rate for volumetric loads of up to 0.7 kg_(N-Namm) m~(-3)d~(-1). The nitrification was not sensitive to the applied COD loads because of the low level of carbon substrate.