Biotrickling Filters For Nitrification Of Nitric Oxide

NO_x is one of the main air pollutants, causing acid rain, being harmful to human health, resulting in the photochemistry smoke and the climate change, endangerring human life and entironment. With the people's attention to nitrogen oxide pollution, various control methods came into being, there are: catalysis, adsorption, absorption, plasma and biological methods. Biological methods are a new type of processing technology developed in recent years, with low-cost, no secondary pollution and so on. According to the nitrification principles, this thesis used bio-trickling filter to treat low concentration NO_x under aerobic conditions.The experiment compared two kindes of nitrobacteria achived in different ways. One was from the domesticated activated sludge, the other was the nitrobacteria finished loading. And then they were inoculated to the active carbon. The potential and difference of the nitrification of the biofilm achieved in two different ways were examined by the continous gas/liquid-phase test under the aerobic conditions. The main effects such as the gaseous flow rate, the recycle liquid flow rate, the NOx influx concentration and the height of the filter media were investigated respectively.The experiment had been carried out under the following conditions: the influx gas concentration was less than 200 mg/m³, the Empty-Bed Residence Time was 44～132 s, the recycle liquid flow rate was 0.05～0.15 L/h, the temperature was 25～30℃, the PH was 7.0～8.0. The results showed that:①With the conditions of contineous aeration, the nitrobacteria obtained both the activated sludge and the finished loading had a good nitrification activity, which the nitrobacteria finished loading had a better purification efficiency;②In the range of the experiment, the removal efficieny of NO2 could reach 100%, the removal efficieny of NO decreases with the increases of the gaseous flow rate and the influx gas concentration. When the recycle liquid flow rate is 0.05 L/h and the influx gas concentration close to 60.00 mg/m3, the purification efficiency could be more than 80%; With the spray liquid increased up to 0.15L/h, the removal efficiency decreased obviously; And then the lowest level of the Bio-filtration filter had the highest removal rate closed to 45%;③From composition of the water testing, the NO₃^- of water accounted for the vast majority, while the NO₂^- accounted for a smaller proportion. It showed that nitrifying bacteria can achieve a more complete nitrification, it had a high nitrification capacity.