Degradation of aflatoxin B1 during anaerobic digestion and its effect on process stability

• Aflatoxins are highly toxic metabolites affecting food and feed production.
• High presence of aflatoxins B1 (AFB1) in maize due to dry seasons.
• Use of contaminated maize for energy production by anaerobic digestion.
• The presence of AFB1 in feeding mix had no adverse effect on biogas production and process stability.
• The high microbial activity characterizing anaerobic digestion allowed ABF1 degradation.

The effect of aflatoxin B1 (AFB1) on an anaerobic digestion process (AD) was studied. Batch anaerobic digestion trials were performed with both non-contaminated AFB1 corn grain (Control A) and contaminated-AFB1 corn grain at different doses (AFB1 contents of 0.54, 66.2, and 110 μg kg−1 wet weight). Both cumulative biogas production and the degradation rate of AFB1 were studied. Results indicated that no adverse effects on AD were detected during the processes which could be attributed to the presence of AFB1. AFB1 degradation ranged from 69% to 87% of the total initial AFB1 content.Anaerobic digestion trials using Completely Stirred Tank Reactors (CSTR) were also carried out, comparing the biogas production of a mix of contaminated corn grain plus pig slurry (AFB1 content of 7.2 μg kg−1 wet weight) with a mix of non-contaminated corn grain plus pig slurry (Control B). No adverse effect of AFB1 on biogas production was detected. The CSTR trial resulted in an average degradation of AFB1 of 42%. The further storage of the digestate for 30 days resulted in an overall degradation (CSTR plus storage) of AFB1 of 61% of the starting content.