Removal of NOx from flue gas using different agricultural wastes as carbon sources: Performance and microbial communities

Abstract

To solve the problem of high cost caused by continuous supply of carbon sources to industrial flue gas denitrification, this study investigated the feasibility of agricultural wastes as carbon sources. In this study, the carbon/nitrogen release from different agricultural wastes was compared by short-effect leaching tests, and the results showed that banana peel and bagasse had a higher carbon release capacity, with chemical oxygen demand (COD) of 1850.58 mg/L and 1022.46 mg/L, respectively. Subsequently, the NOx removal performance of a biotrickling filter-anaerobic baffled reactor (BTF-ABR) integrated system with glucose, banana peel leaching solution, and bagasse leaching solution as carbon sources was investigated under thermophilic (50 ± 3 ℃) micro-oxygen (3% O2) condition. The findings revealed that the maximum NOx removal efficiency from all the carbon sources reached more than 97%, with almost no NO3--N and NO2--N accumulation during the entire process. However, using agricultural wastes as carbon sources resulted in higher NH4+-N accumulation than glucose. Illumina high-throughput sequencing indicated that Actinobacteriota, Patescibacteria, and Firmicutes were the dominant members. In addition, bacterial function analysis showed that agricultural wastes as carbon sources had more abundant carbon metabolism function. These results provide new insights into using agricultural wastes as carbon sources for removing NOx from flue gas.