Development of a flow biocatalytic-based platform for electrochemical monitoring of urea in wastewater

The early evaluation of urea content in water and wastewater is of utmost importance for preventing pollution and improving remediation technologies, also related to urea conversion into a valuable energy product. In this work, a customized urease-based potentiometric platform for the detection of urea in wastewater samples was developed. Amino-functionalized glass beads were used as support material for urease immobilization in a customized bioreactor; then, using an online flow measurement setup, the NH4+ produced by the enzymatic reaction was measured by means of a potentiometric sensor housed in a customized flow cell. Operational and analytical parameters were optimized to achieve the best bioreactor performance. An in-depth study of the composition of the measurement buffer was also carried out; its influence on the sensitivity and detection limits was investigated, demonstrating that a careful selection of its concentration needs to be performed based on the type of samples to be analyzed (LOD = 8.9 ∙ 10−6 M). Finally, at the optimized operative conditions, the full system was applied to the determination of urea in spiked wastewater samples. Using the standard addition method, an average percentage of recovery of 102 ± 5 % was obtained for the analyzed samples despite the interferents present, demonstrating a possible application of the developed setup for remote online urea monitoring in wastewaters.