Abstract
Tofu wastewater is a major contributor to organic pollution in many Asian rivers; however, household-scale tofu production in eastern Indonesia remains poorly documented. This study provides an integrated characterization of tofu and its wastewater in the Telaga Subdistrict, Gorontalo, as baseline information for local water management. The proximate composition of tofu and wastewater was determined following standard AOAC methods, and river water was sampled at three points: upstream (A), downstream (B), and the wastewater channel (C). Contamination parameters (COD, BOD, TSS, ammonia, and pH) were assessed and compared using one-way analysis of variance (ANOVA) with Tukey’s test. Tofu retained high moisture and moderate protein levels, confirming its role as an affordable protein source, while the wastewater still contained soluble proteins and carbohydrates. At Point C, COD (7499 mg.L-1), BOD (864 mg.L-1), and TSS (147 mg.L-1) substantially exceeded national and international thresholds, whereas ammonia (0.01–0.10 mg.L-1) and pH (7.2–7.3) remained within regulatory limits and were lower than those commonly reported for tofu effluents elsewhere. Although wastewater flow was not measured, the very high organic concentrations indicate that even household-scale tofu industries can exert considerable local organic pollution pressure and should be included in water quality monitoring and lowcost treatment programs. At the same time, the presence of residual nutrients suggests potential for valorization pathways such as biogas generation or microbial biomass production, which should be explored in future studies to support context-appropriate circular economy initiatives in Gorontalo.