denitrification via nitrite in a modified uasb reactor using chilean zeolite as microbial support

the general objective of this study was to develop a highly efficient, economical andintegrated technology for the removal of nitrogen compounds through denitrification via nitrite. toachieve this, a modified uasb reactor was designed, set-up and operated using chilean zeolite asmicrobial support. the results were compared to a conventional uasb reactor used as control. thevolume of each reactor was 2 l. the reactors operated with synthetic wastewater under the sameoperating conditions (with superficial velocities, vs, of up to 1 m/h) in the first part of the experiment.later, during the second part of the experiment, only the modified uasb was used, with vs of up to5.5 m/h. in the first part of the experiment, a higher velocity of denitrification in the reactor withzeolite was obtained. nitrogen removal at the end of this experimental set for both reactors, with a vslower than 1 m/h, was 87%. in the second stage, the modified uasb reactor operated at vs ofbetween 1.5 and 5.5 m/h. here, it was observed that the removal of nitrite increased significantly.specifically, at vs values of 2.5, 4.0 and 5.5 m/h, a value of the nitrogen loading rate (nlr) of 1.22 kgn-no2 -/m3/d was kept constant, achieving nitrogen removal efficiencies of 50%, 65% and 95.5%respectively. this last value proves how highly effective the modified uasb reactor is when operating with vs as high as 5.5 m/h.