Assessment of the Biochemical Methane Potential of Wastewater and Sludge Cake from a Poultry Slaughterhouse

Abstract

Objectives This study evaluates the potential for resource recovery through anaerobic digestion of organic waste generated in a poultry slaughterhouse, specifically focusing on poultry slaughterhouse wastewater and sludge cake obtained from in-house wastewater treatment. Methods Basic characteristics (total solids, alkalinity, etc.), total nitrogen/ammonia nitrogen, and elemental analysis (macro and trace elements) were performed to determine the properties of the samples and calculate theoretical methane potential. Experimental methane potential was determined through BMP tests, with parameters such as lag period (λ) and maximum methane production rate (CH4 mL/g VS/d) obtained using the modified Gompertz equation. Results and Discussion The wastewater exhibited low organic matter concentration (1.79 g VS/kg; 3.74 g COD/L), while the sludge cake showed high total solids content (TS 170.8 g/kg) and organic matter concentration (131.5 g VS/kg; 220 g COD/L). Elemental analysis revealed that the C/N ratio was 9.17 for the sludge cake and 8.24 for the wastewater, indicating high nitrogen content. Methane production modeling using the modified Gompertz equation revealed a lag period of 7.5 days and T80 (time to produce 80% of total methane) of 21 days for wastewater, and a lag period of 2.4 days and T80 of 14 days for sludge cake. Conclusion Wastewater and sludge cake from poultry slaughterhouses show significant potential as substrates for anaerobic digestion. However, the wastewater has low organic matter content, and the sludge cake, while high in organic matter, has low moisture and high ammonia levels. Therefore, it may be appropriate to co-digest these two substrates, or to co-digest the sludge cake with other substrates that have low nitrogen content and high water content. These findings provide fundamental data for the anaerobic digestion of slaughterhouse waste and highlight the need for further research on co-digestion and continuous processes.

Keywords

• slaughterhouse waste
• poultry wastewater
• sludge cake
• anaerobic digestion
• biogas