COD's Level Reduction of Tofu Industrial Wastewater by Using Activated Coal Fly Ash as Adsorbent

Tofu wastewater contained a high concentration of COD and will be dangerous if directly discharged into the environment without any pre-processing. In this research, tofu wastewater is processed using an adsorption process to determine the amount of COD reduction in tofu wastewater using coal fly ash. To maximize the adsorption process by enlarging the fly ash's pores and removing the impurities, fly ash is activated first by using 2 M of H2SO4 100 mL. Fly ash was tested with XRD (X-Ray Diffraction) to know its crystal structure and tested with XRF (X-Ray Fluorescence) to determine the difference in the elemental composition of fly ash before and after the activation process. The research on the effect of time on the adsorption process was carried out with time variations of 15, 30, 45, 60, 75, 90, 105, and 120 minutes. The results showed that the intensity of silica in the fly ash after the activation process was more significant than before the activation process. The optimum time for fly ash to adsorb tofu wastewater was 105 minutes with eficiency of 79,71%.