The facility treatment team conducted the third operation for the treatment of PCB in transformer oil using the sodium destruction method. The general objective is to lower the concentration to 2 ppm or below. A 3049 L of contaminated oil was subjected for treatment and six (6) samples from 1 R01 tank (reactor) were received in the laboratory for analysis. After 159 L injection of sodium and 12.75 hours of reaction process, the final concentration of PCB is 37.52 ppm. The reaction time was increased per injection per 3 hours but important parameters that must be considered in the low reduction of PCB concentration are the ratio of sodium and chlorine, particle size of the sodium dispersed, and temperature in the reaction chamber.
Can you help me provide a hypothesis on the root cause of why this happened?