Using some catalysts in hydrothermal pretreatment to improve the efficiency of anaerobic digestion of pig manure
The strong development of pig farms in Vietnam in recent times has brought high economic efficiency but has negatively affected the quality of the surrounding environment due to waste and not being thoroughly treated. Therefore, the research and application of advanced technologies to treat waste and minimize pollution at pig farms is an urgent task to ensure sustainable development of the livestock industry. Anaerobic biodegradation is considered a suitable solution to treat waste with high concentrations of organic matter and solids such as pig waste. Producing biogas from waste is a solution that creates dual benefits: minimizing pollution and turning waste into a useful source of clean energy. The anaerobic decomposition process of waste includes four stages: hydrolysis, fermentation, acetation and methanation. However, the hydrolysis stage is considered to be the stage with limited decomposition rate. To improve the anaerobic decomposition process, waste pretreatment is a useful solution to help break the bonds of high molecular compounds such as lipids, proteins, carbohydrates, etc. into simpler substances, increasing the solubility of organic substances in the liquid phase. Pretreatment methods include heat, chemistry, biology, mechanics, etc. In which, hydrothermal pretreatment is the process of pretreating organic matter under the influence of temperature and pressure. This process helps increase the amount of dissolved organic matter in the liquid phase, helping microorganisms to decompose easily during the anaerobic decomposition process, thereby increasing the productivity of methane. This process is commonly applied in sludge treatment but is less common in pig manure treatment. Therefore, in this study, we used hydrothermal pretreatment combined with some catalysts to increase the solubility of organic matter before performing anaerobic decomposition in order to increase biogas production.