Evaluating the effects of SLBD supplementation on biogas production from dairy cattle manure during anaerobic digestion

Abstract

Livestock manure is one of the largest organic waste streams generated by agricultural systems worldwide. Improper management of manure can contribute to environmental problems, including greenhouse gas emissions, nutrient losses, water contamination, and odor pollution [1]. In dairy production systems, manure contains substantial amounts of organic matter that can be utilized as a renewable energy source through anaerobic digestion. This technology simultaneously addresses waste management challenges while producing biogas, a renewable energy source that can reduce dependence on fossil fuels [2]. Anaerobic digestion is a biological process in which microorganisms decompose organic materials under oxygen-free conditions, resulting in the production of methane (CH₄), carbon dioxide (CO₂), and stabilized digestate [3]. The efficiency of anaerobic digestion depends on several factors, including substrate composition, microbial populations, pH, temperature, and retention time [4]. Dairy cattle manure is widely used as a substrate for anaerobic digestion due to its high moisture content and abundant microbial population. However, the degradation of lignocellulosic components remains a limiting factor affecting biogas yield and methane production [5]. To improve the efficiency of anaerobic digestion, various microbial additives have been investigated. Effective Microorganisms (EM4), consisting of mixed cultures of beneficial microorganisms such as lactic acid bacteria, photosynthetic bacteria, yeasts, and actinomycetes, have been reported to enhance organic matter decomposition and improve biogas production under certain conditions [6]. Recently, microbial inoculants containing enzyme-producing bacteria have attracted increasing attention due to their ability to accelerate the hydrolysis stage, which is often the rate-limiting step in anaerobic digestion [7]. ...