Anaerobic Digestion of Blood from Slaughtered Livestock: A Review

Blood from livestock slaughtering imposes a high organic pollution load and risks. If it is discharged untreated to sewer systems, it increases the organic pollution load on wastewater treatment plants by 35-50%. This paper reviews blood anaerobic digestion. It analyzes the quantities, composition, methane potential reported, microbiology, biochemical pathways of blood protein degradation, environmental and health issues, and strategies suggested to manage them during livestock blood anaerobic digestion. Although challenging, anaerobic digestion of blood as a mono-substrate is possible if the culture-reactor system is controlled based on a complete characterization and understanding of the microbial community and its metabolic activities. Co-digestion of blood and other feedstock proceeds well if the mixtures are well designed. Generally, the specific methane yield from digesting blood alone ranges between zero and 0.45 m(3) kg(-1) protein, whereas for co-digesting blood and other substrates, the yield varies between 0.1 and 0.7 m(3) kg(-1) volatile solids. More research is required for microbiology and kinetics, the role of adsorbents, reactor configuration, and culture adaptation during anaerobic digestion of blood to better control the process.

Automated summary

Blood from livestock slaughtering poses a high organic pollution load and risks, increasing the load on wastewater treatment plants if discharged untreated to sewer systems. Anaerobic digestion of blood can be achieved as a mono-substrate or co-digested with other feedstock by controlling the microbial community and metabolic activities. More research is needed to better control the process through microbiology, kinetics, adsorbents, reactor configuration, and culture adaptation during anaerobic digestion of blood.