Autotrophic Denitrification Using Elemental Sulfur to Remove Nitrate from Saline Aquarium Waters

Abstract

The goal of this research was to elaborate an effective and economical treatment system to eliminate nitrates from a large marine basin at the Aquarium du Québec. Several configurations of an autotrophic denitrification system using elemental sulfur were tested. Results showed that inoculums taken from various environments (soil, sewage sludge, wetland, pig manure, marine sediment) could be used to prepare denitrifying microbial cultures for a marine environment. Subsequent trials using a continuous-flow configuration with columns containing sulfur granules showed that a hydraulic retention time (HRT) of 16–19 h allowed the removal of nearly all of the nitrates present in the water ([NO3-N]i=25–30 mg L−1). Furthermore, this study demonstrated that the insertion of oyster shell columns between the sulfur-containing columns led to an increase in pH and alkalinity of the treated water, maintaining a favorable denitrifying environment.