Gaseous emission and maturity in composting of livestock manure and tobacco wastes: effects of aeration intensities and mitigation by physiochemical additives

This study investigated the effects of aeration intensities (i.e. 0.2, 0.4, 0.6 L kg DM⁻¹ min⁻¹) on gaseous emissions and maturity during composting of livestock manure and tobacco wastes. Bamboo biochar and calcium superphosphate were then supplemented to amend the composting process at a suitable aeration intensity. Results show that the aeration intensity of 0.4 L kg DM⁻¹ min⁻¹ was more favorable to accelerate composting progress, but resulted in much higher gaseous emission than other two conditions. By the end of 35 days of composting, the seed germination index (GI) of all compost products was lower than 80%, although such phytotoxicity could be slightly improved at higher aeration intensity. Nevertheless, biochar and calcium superphosphate could effectively reduce gaseous emission and improve compost maturity. In particular, biochar exhibited a better performance to reduce the emission of greenhouse gas and ammonia by 93.61% and 51.42%, respectively. Furthermore, compost phytotoxicity could be eliminated with GI increase to above 100%.