Factoring distinct materials and nitrogen-related microbes into assessments of nitrogen pollution risks during composting.

[Display omitted] • Nitrogen Pollution risks in chicken manure composting (CM) was continuous. • Maximum total nitrogen content and pollution risk were observed in CM. • Pollution risks of municipal solid and straw waste concentrated in heating phases. • Pollution risk from denitrification was the most serious in municipal solid waste. • The genes (pmoC-amoC , nrfH , nifD etc.) were related to nitrogen pollution risks. The aim of this study was to evaluate nitrogen pollution risks from distinct materials composting with the discrepancy of component, including chicken manure, municipal solid and straw waste (CM, MSW, SW). Results showed total nitrogen maximum mean concentrations were observed in CM (39.57 g/kg). Pollution risks in CM were continuous, while MSW and SW mainly concentrated during heating phases. Microbial analysis confirmed that pollution risks from ammonification and nitrification were more prevalent in CM. The risks of pollution caused by nitrate reduction accompanied N 2 O were the most serious in MSW. The multifunctional nitrogen-related microbes P seu domonas and Bacillus were affected by microenvironments and contributed to different pollution risks. Furthermore, PICRUSt analysis identified the "inferred" key genes (pmoC-amoC , nrfH , nifD etc.) related to nitrogen pollution risks. This study evaluated nitrogen pollution risks and proposed the future directions, providing theoretical basis and feasible optimization measures for the mitigation of nitrogen pollution during composting. [ABSTRACT FROM AUTHOR]