Effects of swine manure storage time on solid-liquid separation and biogas production: A life-cycle assessment approach. (October 2021) - Hollas, C.E.
Abstract: In the present study was evaluated and compared the effects of swine manure storage on a low-cost solid-liquid separation approach. We also determined the consequences of these stages on further treatment for energy recovery and environmental impact reduction. Different hydraulic retention times were studied in the solid-liquid separation techniques to determine the best pre-treatment conditions and apply these conditions in anaerobic digestion. This evaluation highlighted the possibility and advantages of applying solid-liquid separation using a settling pre-treatment in the swine chain. Storage time significantly affected the efficiency of screening which was reduced by 80 ± 0.5% after 5 d compared to fresh manure screening. This directly reflected the sludge volume generated in the following stages, with sludge increments of 51 ± 0.1% for settling. The waste solid-liquid separation provided better energy production results when the manure storage time was less than 5 d, resulting in improved power generation capacity of the system (up to 4.5 kWh of electricity for each m 3 of raw manure). We observed the positive contribution of adequate manure management in swine sustainability through the life-cycle assessment of the swine chain during manure storage, solid-liquid separation, and anaerobic digestion. It promoted low greenhouse gas emissions, resulted in a carbon-neutral chain, and maximized energy production and recovery. The results highlighted the importance of previous solid-liquid separation in anaerobic digestion and the relevance of proper effluent management because more than 5 d of storage time compromised subsequent processes. This was also observed during the life-cycle assessment. Graphical abstract: Image 1 Highlights: The life cycle analysis pointed out the impacts of waste management strategies. The storage time significantly affected the solid-liquid separation approaches. The manure storage time should not exceed 5 days. Higher methane yield was obtained in supernatant fraction. Solid-liquid separation and correct manure management favors biogas yield.