Nitrite removal in a submerged biofilter.

ABSTRACT

Nowadays submerged filters seem to be the preferred technology for denitrification purposes. Optimisation of biological nitrogen has recently been tried based the nitrate shunt in order to save two of the involved steps. Former studies have shown that a build-up of nitrite can be achieved by an appropriate control of the nitrification process either in suspended cultures or in fixed cultures. An experimental plan was conducted to study the effect of different types of carbon source (acetate, ethanol and urban wastewater) on the performance of a submerged down flow biofilter, as well as the influence of the hydraulic loading. Results have shown that maximum nitrogen removal rates were similar for acetate and ethanol attaining values significantly higher than for urban waste water. On the other hand, nitrogen massic loading appeared to be the limiting factor for efficiency rather than hydraulic loading.