Low-temperature biochars are more effective in reducing ammonia emissions through various mechanisms during manure composting

• Published in: Journal of material cycles and waste management Vol. 26; no. 1; pp. 138 - 148
• Main Authors: Shin, Yunsik, Iwabuchi, Kazunori, Itoh, Takanori
• Format: Journal Article
• Language: English
• Published: Tokyo Springer Japan 2024; Springer Nature B.V
• Subjects: Ammonia; Cation exchange; Cation exchanging; Charcoal; Civil Engineering; Composting; Emissions; Engineering; Environmental Management; Functional groups; Heterogeneity; High temperature; Low temperature; Manures; Nitrification; Nitrogen; Original Article; Physicochemical properties; Pyrolysis; Raw materials; Temperature; Waste Management/Waste Technology; Pyrolysis temperature; Feedstock; Nitrogen loss; Adsorption; Nitrification
• ISSN: 1438-4957; 1611-8227
• DOI: 10.1007/s10163-023-01808-3

Biochar is an effective additive for reducing ammonia emissions during composting due to its unique physicochemical properties. However, the properties of biochar vary according to production conditions such as the feedstock and pyrolysis temperature. This heterogeneity may affect the ammonia mitigation performance of biochar during composting, but few studies have investigated the effect of biochar properties on ammonia emissions. Here, we prepared four types of biochar from two feedstocks (dairy manure and Japanese larch) at two pyrolysis temperatures (300 °C and 800 °C) and compared their impact on ammonia emissions during composting. The composting experiments were conducted on a laboratory scale by mixing each biochar (12 g) with dairy manure (300 g) for 19 days. The results showed that biochar addition (10.7–15.3% initial total nitrogen) significantly lowered ammonia emission rates compared to dairy manure alone (18.6% initial total nitrogen), and low-temperature biochars showed better performance than high-temperature biochars. We propose that ammonia emissions are reduced by biochar due to NH 4 + adsorption and increased nitrification. Abundant surface oxygen-containing functional groups, high cation exchange capacity, high ash content, and low pH are likely the dominant factors reducing ammonia emissions, while high specific surface area is less influential.