Experimental Investigation and Modeling of Denitrification of Water in a Column Bioreactor Using Immobilized Microorganisms on Modified Zeolite

The effectiveness of nitrate removal was assessed in a 9.5 L packed bed column bioreactor through the evaluation of various feeding strategies and initial concentrations. The bioreactor was filled with zeolite mineral particles and initially treated with Thiobacillus denitrificans. Multiple hydraulic retention times were investigated to determine the efficiency of nitrate removal. The results demonstrate that the designed bioreactor is capable of achieving an 87% reduction in nitrate levels within a three-hour timeframe. This indicates that the bioreactor system can effectively remove nitrate ions from water, even when the initial nitrate content is as high as 400 mg/L, which exceeds the standard limit of 45 mg/L. The computational fluid dynamics (CFD) model yielded satisfactory results, confirming the effectiveness of the bioreactor design. It revealed that the optimal length of the bioreactor is suitable for influents containing 400 mg/L of nitrate. However, for influents with lower nitrate concentrations or when employing lower hydraulic retention times (HRTs), the bioreactor can be constructed with shorter heights. This CFD model can serve as a valuable tool for future studies, particularly in scaling up the bioreactor system.