The tofu production process produces liquid waste, where the waste contains high enough proteins and can decompose. However, suppose the waste is not processed correctly before discharge into the river without passing through the decomposition. Then, it will damage the biota due to changes in pH value. The liquid waste treatment could decrease the Total Suspended Solid (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD).

UNY students do many activities to maintain the waters, one of which initiates Gerakan Pengoptimalan Sungai (GPS) activities in Semoyan village of Yogyakarta. GPS increases people's knowledge and awareness about the importance of maintaining the cleanliness of the river environment and local fish care. Youths put up banners regarding the ban on polluting rivers in some locations.