The effect of urea addition on biogas production from beneng taro starch wastewater

Anaerobic digestion (AD) applied to Beneng taro starch wastewater (BTSW) presents an attractive route for combining wastewater treatment with renewable energy recovery.Nevertheless, biogas generation from this type of substrate is often constrained because carbohydrate-dominated wastewater tends to contain insufficient nitrogen to support optimal microbial function.Accordingly, this study was designed to determine how nitrogen supplementation through urea influences the performance of AD when BTSW serves as the substrate.The experiment was performed in 500 mL batch digesters using a substrate and inoculum mixture at a volumetric ratio of 80:20.Urea concentrations of 0, 100, 150, 200, and 250 mg/L were evaluated, while FeCl 3 was maintained at 60 mg/L.Among these treatments, the 150 mg/L urea dose gave the largest cumulative biogas output (187.86 mL/g-TS substrate ), roughly triple that of the untreated control, and also produced the greatest methane yield (54.39 mL CH 4 /g-TS substrate ), the smallest buildup of VFAs, and the strongest reductions in TS (32.69%),TSS (33.33%), and TDS (32.10%).Kinetic evaluation with the modified Gompertz equation further confirmed this outcome, showing a very close fit to the experimental data (R 2 = 0.9979) and the largest Pm value (187.90 mL/g-TS substrate ) among all treatments.Overall, these outcomes point to 150 mg/L as the most suitable urea dose for supplying nitrogen during BTSW digestion and for maximizing biogas output.