Denitrification via Nitrite in a Modified UASB reactor using Chilean zeolite as Microbial Support

Document Type: Original Research Paper

Authors

1 1Department of Chemical and Environmental Engineering, Federico Santa Mar1a Technical University, Ave. España 1680, Valpara1so, Chile

2 Department of Chemical and Environmental Engineering, Federico Santa Mar1a Technical University, Ave. España 1680, Valpara1so, Chile

3 Department of Chemical Engineering, Santiago de Chile University, Ave. Lib. Bernardo O’Higgins 3363, Santiago de Chile, Chile

4 Instituto de la Grasa (CSIC), Avda. Padre García Tejero, 4, 41012-Sevilla, Spain

Abstract

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, 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 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 vs
lower than 1 m/h, was 87%. In the second stage, the modified UASB reactor operated at vs of
between 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 kg
N-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.

Keywords