Thauera sp. in Hydrogen-Based Denitrification: Effects of Plentiful Bicarbonate Supplementation on Powerful Nitrite Reducer.

Nitrite accumulation in hydrogen-based denitrification (HD) has been reported as a difficulty for achieving complete denitrification. Thauera sp. has been found as the dominant bacterial species in HD previously when using a plentiful amount of HCO₃⁻. This present study was successful in isolating Pseudomonas sp., Dietzia sp., Pannonibacter sp., Halomonas sp., Bacillus sp., and Thauera sp. These isolated strains were selected for investigating the nitrogen removal performance under the plentiful HCO₃⁻ condition. Only Pseudomonas sp. and Thauera sp. were capable of removing NO₂⁻ where the specific NO₂⁻ removal rate of Thauera sp. (36.02 ± 5.66 mgN gVSS⁻¹ day⁻¹) was 9 times quicker than that of Pseudomonas sp. (3.94 ± 0.80 mgN gVSS⁻¹ day⁻¹). The Thauera sp. strain was then tested at different HCO₃⁻ amounts. As a result, Thauera sp. had no ability to function both NO₃⁻ and NO₂⁻ removals under HCO₃⁻ deficit condition. This study provided evidence on the role of Thauera sp. and the necessity of bicarbonate in the hydrogen-based denitrification process to enhance its efficiency and to simultaneously reduce the operational cost especially for hydrogen. [ABSTRACT FROM AUTHOR]