Beneficial Microorganisms in the Anaerobic Digestion of Cattle and Swine Excreta

Abstract

The accumulation of solid organic waste is reaching critical levels in almost all regions of the world. It must be managed sustainably to avoid the depletion of natural resources, minimize risks to human health, reduce environmental burdens, and maintain an overall balance in the ecosystem. This research focuses on the anaerobic digestion of bovine and swine excreta with and without applying beneficial microorganisms as a viable option for recycling agricultural solid wastes. Three greenhouse gases (GHGs)—methane, carbon dioxide, and ammonia—produced by cattle and swine excreta that were treated with and without beneficial microorganisms in bioreactors were quantified. A monitoring and gas concentration measurement system was implemented inside the bioreactors. The behavior of the GHGs and the efficiency of the beneficial microorganisms in treating the farm animal waste were analyzed according to the phases of anaerobic digestion. Average reductions in the concentration in units of ppm of CH4 during the composting process of 46.95% and 34.48% were observed for the cattle and swine excreta treatments, respectively. It was concluded that the studied GHGs had different behaviors in the anaerobic digestion of the treatments in cattle and swine excreta with and without beneficial microorganisms due to the different types of feeding. However, it must be emphasized that beneficial microorganisms are an essential tool for reducing GHGs in anaerobic digestion.