Separation of swine wastewater into solid fraction, concentrated slurry and dilute liquid and its influence on biogas production

Abstract

Swine wastewater was separated into a solid fraction and a liquid fraction in a biogas plant using a separator with hydraulic wedge-shaped sieve. The liquid fraction (separated slurry) was further separated into concentrated slurry and dilute liquid by gravity sedimentation in the laboratory. Components and methane production of the solid fraction accounted for about 15% of those of the raw wastewater. The majority of the organic matter and phosphorus (more than 60%) were distributed in the concentrated slurry. The concentrated slurry represented 15% of the volume of initial wastewater but produced more than 70% of the total methane production. The condensation of the pollutants and nutrients in the concentrated slurry can facilitate land application of digestate. The dilute liquid with less organic matter and nutrients can be treated easily using less expensive and easier treatment options.