Application of central composite design approach for optimization nitrate removal from aqueous solution by immobilized Pseudomonas putida

High Nitrate concentration represented as one dangerous pollutant in the environment. Immobilization for the best denitrifying bacterial strain isolated from collected wastewater samples was suggested for bioremediation excessive nitrate concentration from aqueous solutions and explored its denitrification activity under different factors as (pH, nitrate concentration, bacterial beads, Temp and sodium alginate concentration). The active isolate was identified as Pseudomonas putida MT364822.1 by 16S rRNA analysis. Nitrate bioremediation process was optimized by apply response surface method based on central composite design approach. Nitrate uptake was significantly affected by variables of study (p-value <0.05). Maximum removal of nitrate 91.1% was obtained from pH 7, nitrate concentration 400 mg/L, immobilized bacterial beads 3.0 g/L, Temp 35 degrees C and sodium alginate concentration 2.5% as optimal variable values. For application, immobilized Pseudomonas putida MT364822.1 removed nitrate with 82.2% from raw fish farm effluent. Storage and reusability experiments showed the strength and stability of immobilized strain more than pure. The results suggested that, immobilized Pseudomonas putida MT364822.1 is a highly promising and suitable microorganism to be used in bio-removal of nitrate and central composite design was more effective in optimization variables to obtain the highest nitrate removal efficiency.