ANALYSIS OF LIQUID NITROGEN COMPONENTS IN BIOLOGICAL AIR SCRUBBER WASHING WATER

To follow up the performance of biological air scrubbers, pH and electrical conductivity (EC) are continuously measured at every scrubber in Flanders and the Netherlands. However, with these two parameters, it is still difficult to get insight in the processes, e.g. and to identify the causes when biological air scrubbers are not reaching the required removal efficiency. EC gives an idea about the total nitrogen content in the water but it does not reflect the ratio of its important components: ammonium (NH4+), nitrite (NO2-) and nitrate (NO3-). In this study, the washing water of two newly build multi-stage biological air scrubbers was measured each week over a period of almost one year, to identify the concentrations of NH4+, NO2- and NO3-, but also pH and EC. Simultaneously, the concentrations of ammonia (NH3) and nitrous oxide (N2O) were measured in the gas phase before and after each scrubber to assess its performance. The two-stage air scrubber was inoculated with activated sludge to facilitate its biological activity.