The objective of this study is to find the optimal combination of factors used in the process of wastewater treatment to collect the suspended rubber content from the disc cleaning process. The factors include the amount of GRASS2 and the waiting time required for the rubber to coagulate. The study was conducted using two sets of experiments. One is to find the deterministic optimal amount of GRASS2 and waiting time, and the other one is to find whether it is practical to use the fiber optic sensor as a tool to indicate the sufficient amount of GRASS2 required. The results from the experiments show that using the fiber optic sensor requires a greater amount of GRASS2 than the deterministic method since the objective function of the sensor model was to maximize light intensity in the wastewater, while the objective function of the deterministic model was to maximize the percentage of the achieved rubber contents.