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

• The separation offered a more effective option for swine wastewater treatment.
• Wastewater was separated into concentrated slurry and dilute liquid by sedimentation.
• The methane production kinetics of separated productions have been investigated.
• The components and methane distribution in products of separation were evaluated.

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.

Cumulative methane production of raw wastewater, separated slurry and their separation products: R1-raw wastewater, R2-separated slurry, DL1-dilute liquid from raw wastewater, DL2-dilute liquid from separated slurry, CS1-concentrated slurry from raw wastewater, CS2-concentrated slurry from separated slurry.Figure optionsDownload as PowerPoint slide