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 and integrated technology for the removal of nitrogen compounds through denitrification via nitrite. To achieve this, a modified UASB reactor was designed, set-up and operated using Chilean zeolite as microbial support. The results were compared to a conventional UASB reactor used as control. The volume of each reactor was 2 L. The reactors operated with synthetic wastewater under the same operating conditions (with superficial velocities, v(s), 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 v(s) of up to 5.5 m/h. In the first part of the experiment, a higher velocity of denitrification in the reactor with zeolite was obtained. Nitrogen removal at the end of this experimental set for both reactors, with a v(s) lower than 1 m/h, was 87%. In the second stage, the modified UASB reactor operated at v(s) of between 1.5 and 5.5 m/h. Here, it was observed that the removal of nitrite increased significantly. Specifically, at v(s) values of 2.5, 4.0 and 5.5 m/h, a value of the nitrogen loading rate (NLR) of 1.22 kg N-NO2-/m(3)/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 v(s) as high as 5.5 m/h.