Effect of tannic acid combined with fluoride and lignosulfonic acid on anaerobic digestion in the agricultural waste management chain

Livestock waste is stored and used as soil fertilizer or directly as substrate for biogas production. Methane emissions from manure storages and ammonia inhibition of anaerobic digesters fed with manure, are well-known problems related to manure management. This study examines the effect of adding tannic acid with fluoride (TA-NaF) and lignosulfonic acid (LS) on methanogenic activity in batch reactors with ammonia inhibited maize silage digestate and in batch reactors with manure. Lignosulfonic acid counteracted urea induced ammonia inhibition of methanogenesis, whereas TA-NaF inhibited methanogenesis itself. Stable carbon isotope ratio analysis and methanogen community analysis suggested that TA-NaF affected acetoclastic methanogens the most. The combined findings suggest that TA-NaF could be used to reduce methane emissions from stored manure. Conversely, LS could be used as supplement in anaerobic digesters prone to urea induced ammonia inhibition.