Optimization of

The most commonly used method for treating river water is the coagulation-flocculation process. However, the use of synthetic coagulants, such as alum and polyaluminum chloride, can harm the environment; therefore, it is essential to find more environmentally friendly alternatives. One potential natural coagulant is Aloe vera. This study aims to analyze the effects of Aloe vera coagulant dosage, stirring speed, and stirring time, and determine the best conditions for using Aloe vera to reduce turbidity and color in Martapura River water. The method used in this research is the coagulation-flocculation process based on the Response Surface Methodology using a Central Composite Design model. The results showed that the optimal conditions for Aloe vera coagulant were a dosage of 20 mL, a stirring speed of 90 rpm, and a stirring time of 8 minutes. Under these conditions, turbidity decreased from 79 NTU to 11.67 NTU with an efficiency of 85.2321%, and color decreased from 92 TCU to 9.25 TCU with an efficiency of 90.0214%. While the turbidity level did not meet the water quality standard of 3 NTU set by the Indonesian Ministry of Health Regulation No. 2 of 2023, the color parameter already complied with the standard limit of 10 TCU.