Modified lignin can achieve mitigation of ammonia and greenhouse gas emissions simultaneously in composting

The constant ammonia gas (NH₃) and greenhouse gases (GHG) emissions were considered as a deep-rooted problem in composting which caused air pollution and global climate change. To achieve the mitigation of NH₃ and GHG, a novel additive derived from wasted straw, with modified structure and functional groups, has been developed. Results showed that the adsorption capacity of modified lignin (ML) for both ammonium and nitrate was significantly increased by 132.5-360.8 % and 313.7-454.3 % comparing with biochar (BC) and phosphogypsum (PG) after reconstructing porous structure and grafting R-COOH, R-SO₃H functional groups. The application of ML could reduce 36.3 % NH₃ emission during composting compared with control. Furthermore, the synergetic mitigation NH₃ and GHG in ML treatment resulted in a reduction of global warming potential (GWP) by 31.0-64.6 % compared with BC and PG. These findings provide evidence that ML can be a feasible strategy to effectively alleviate NH₃ and GHG emissions in composting.