Speaker
Description
Anaerobic co-digestion of food waste (FW) and chicken droppings (CD) offers an opportunity to recover nutrients from organic wastes. However, digestion performance and liquid organic fertilizer quality depend on inoculum adaptation conditions, substrate composition, and digestion duration. This study evaluated the effects of cow-manure inoculum adaptation temperature, substrate ratio, and digestion period on digestion performance and the potential liquid organic fertilizer (LOF) quality. Cow manure inoculum was incubated at 25 °C and 37 °C for 7 days. The inoculum adapted at 37 °C was selected for the subsequent experiments based on its lower total solids and chemical oxygen demand and higher alkalinity. Laboratory-scale digestion was performed at 37 °C for 15, 30 and 60 days using 100% FW and 100% CD as mono-digestion controls and four FW:CD co-digestion ratios: T1 = 90:10, T2 = 80:20, T3 = 70:30, and treatment T4 = 60:40. A substrate-to-inoculum ratio of 90:10 was maintained across all treatments. The liquid digestate was characterized for physicochemical properties, macronutrients, minerals, and trace metals. Among the co-digestion treatments, T4 contained 3,920 mg/L nitrogen and 5.75 mg/L phosphorus at 60 days, with a pH of 7.64. Its potassium concentration was 62.1 mg/L at 60 days, although it peaked at 106 mg/L at 30 days. T3 showed the largest reported volatile-solids reduction, from 76.5% at 15 days to 43.5% at 60 days. These findings indicate that substrate composition and digestion duration influenced nutrient concentrations and organic-matter conversion. T4 may be suitable for producing a potential supplementary LOF, whereas T3 showed greater organic-matter stabilization. Further agronomic validation, pathogen assessment, and monitoring of soil salinity and trace metals are required before practical application.