Isolation and characterization of a novel denitrifying bacterium with high nitrate removal: Pseudomonas stutzeri

The aim of this study was to isolate and characterize a high efficiency denitrifier bacterium for reducing nitrate in wastewater. Six denitrifier bacteria with nitrate removal activities were isolated from a petrochemical industry effluent with high salinity and high nitrogen concentrations without treatment. The isolated bacteria were tested for nitrate reomoval activity. One of the bacterium displayed the highest reduction of nitrate. The strain was preliminarily identified using biochemical tests and further identified based on similarity of PCR-16S rRNA using universal primers. Biochemical and molecular experiments showed that the best bacterium with high nitrate removal potential was Pseudomonas stutzeri, a member of the alpha subclass of the class Proteobacteria. The extent of nitrate removal efficiency was 99% at 200 mg/L NO[3] and the nitrite content of the effluent was in the prescribed limit. The experiments showed the ability of Pseudomonas stutzeri to rapidly remove nitrate under anoxic conditions. The strain showed to be potentially good candidate for biodenitrification of high nitrate solutions

Application of impregnated almond shell activated carbon by zinc and zinc sulfate for nitrate removal from water

In this study impregnated almond shell activated carbon by Zn° and ZnSO[4] were used as adsorbent with a particle size of 10-20 mesh. The objective of this research was to determine the ability of impregnated activated carbon in nitrate removal. The modified activated carbon had 1mm effective size, with a uniformity coefficient of 1.18. Potassium nitrate solution was used in batch adsorption experiments for nitrate removal from water. The effects of nitrate concentration, activated carbon dosage and time of contact were studied. Experimental data showed that modified activated carbon by Zn° and ZnSO[4] was more effective than virgin almond activated carbon for nitrate removal. The maximum nitrate removal was 64%-80% and 5%-42% for modified activated carbon and virgin activated carbon, respectively. While virgin activated carbon used, nitrate-N decreased from 20 to 15mg/L in 30min reaction. The final nitrate concentration was not in the standard range of WHO recommendations for water quality; while impregnated activated carbons were used, nitrate drcreased to <10mg/L. Maximum removal was over 16-17mg nitrate-N per 1g activated carbon for impregnated activated carbon. The experiments were conducted at pH=6.2, 20°C and initial concentrations of 20mg/L nitrate-N. Increase in modified activated carbon dosage increased the nitrate removal efficiency. The equilibrium time was found to be 45min for modified activated carbon