A Novel Application of Combined Biological and Physical Method for Nitrate and Nitrite Removal from Water

Large amounts of nitrate and nitrite in water cause different diseases in human and jeopardize plants and animals growth cycles. In this study in order to remove nitrate and nitrite ions from input of sample water, including high concentrations of nitrate by combining biological and physical methods a pilot was designed and tested. It should be noted that industrialization, cheap and availability of used materials in this pilot are benefits of this pilot.

The pilot was designed in the form of a cube with four drawers and a glass chamber at one end. The pilot drawers were filled with sawdust, wastewater (wastewater treatment plant in Islamic Azad University, Tehran) of treatment plant, including the best strain, handmade nitrate solution, the bentonite and twice washed sand. The experiments showed that the designed pilot in addition to the elimination of nitrate also removes the nitrite of the medium. The concentration of nitrate and nitrite was analysed by HACH/DR5000 spectophotometer.

In the case of the pilot performance of the continuous system and using the strains taken from the wastewater of the treatment plant after the aeration phase, the nitrate and nitrite removal efficiency of the input of sample water in 20 minutes retention time were measured 74.84% and 99.8% respectively. Additionally, in the case of the pilot performance in the continuous system and using the strains taken from the sludge of the treatment plant wastewater before the aeration phase and the yeast, the nitrate and nitrite removal efficiency in 20 minutes retention time were measured 72.63% and 56.33% respectively. 

Discussion and Conclusion:

During the experiments, the designed pilot had a promising role in the nitrate and nitrite removal. In the case of the pilot performance of the continuous system and using the strains taken from the wastewater of the treatment plant after the aeration phase, the maximum amount of nitrite and nitrate ions were removed. It should be noted that through the pilot performance in all cases, pH and temperature had an increasing and decreasing trend respectively.