Environmental engineers suggest that anaerobic digestion could be used to clean cattle manure, produce fuel

Chemicals—from antibiotics used to keep livestock healthy to pesticides that shield crops from insects and other pests—play an important role in modern agriculture. However, many of these substances accumulate in cow manure used as fertilizer, where they contaminate crops, leach into groundwater, and pollute waterways, posing a threat to human health and the environment.