Residence Time Distribution Study in Laboratory Scale Struvite Crystallization Reactor with Online Conductivity Measurement

Abstract

Elimination Residence time distribution (RTD) analysis is necessary to explain the hydrodynamic behavior of a continuous stirred tank reactor. In this study, RTD was applied in a laboratory scale struvite crystallization reactor to estimate the degree on non-ideality and its effect on the reactor performance i.e. effective volume, actual hydraulic residence time (HRT), and material dispersion. An impulse-response tracer (NaCl saturated solution) approach and a conductivity meter to detect of the NaCl at the effluent of the reactor were applied. To evaluate effects on the reactor performance, variation of impeller locations, impeller speeds, and flowrates were conducted. The main findings from this study showed that the difference between actual and theoretical HRT was found around as around 10%-34% and 30%-37% for condition of the impeller location at the upper and lower part, respectively. These percentages were corresponding to the reactor’s effective volume, lower percentage means higher effective volume. This finding correlated to the value of dispersion number. It was found to be about 1.612 and 0.49 for the impeller location at the upper and lower part, respectively. Finally, it was observed that the tracer was being almost 100% recovered in the reactor due to a good flow pattern and its impeller location affects the reactor’s performance.