Improved biogas production by anaerobic co-digestion of whey and bovine manure: A case study in Montevideo-Peru

Improved biogas production through anaerobic co-digestion of cattle manure and whey is presented as a viable strategy for energy sustainability, especially in rural settings. Despite its potential, there are limitations related to the selection of appropriate mixing ratios and biodigester design, which impact the efficiency of the process. This descriptive and experimental research addresses these limitations by evaluating the 80:20 (manure: whey) mixture and incorporating innovations such as a manual stirrer and a greenhouse that maintains stable mesophilic conditions at 37 °C. In the study, the average daily production is around 42.78 litres of CH₄ per kilogram of organic matter, with a methane content of 54.2%, exceeding theoretical predictions by 12.3%. In addition, the resulting digestate had an average NPK ratio of 1.75-0.5-0.25 g/l, increasing agricultural yields by 20 %. From an environmental point of view, a mitigation of 2.6 tonnes of CO₂ equivalent per year was achieved, highlighting the system’s contribution to the reduction of greenhouse gas emissions. This methodological approach demonstrates the technical, environmental and economic feasibility of co-digestion, offering a replicable and sustainable solution for rural communities. The results obtained reaffirm the importance of perfecting the design and operation of biodigesters, highlighting their potential to promote a circular economy model with positive impacts at local and regional scales.