Reduction of allelochemicals during composting of lignocellulosic biomass: identification and transformation mechanism of allelochemicals

The terrestrial plant Lantana camara L. is well-known terrestrial plant because of its allelopathic activities, which affect the germination and yield of other crops. The study aimed to convert this plant into a value-added compost product, as its characterization revealed significant amounts of volatile solids and nutrients. The study also sought to investigate the identification and transformation of toxic organic compounds during the in-vessel composting of L. camara using a 550 L rotary drum composter. As per the Central Composite Design - Response Surface Methodology (CCD - RSM), the optimal ratio for terrestrial biomass to inoculum (cow manure) and bulking agents is determined to be 5:4:1. The results showed that the 20th day compost showed an increase in Total Kjeldahl Nitrogen (TKN) (37%), available phosphorus (78%), and potassium (22%), respectively, compared to the initial feed. The 25% concentrated final day compost extract was found to be the best dose in phytotoxicity, cytotoxicity results of Vigna radiata (L.) R. Wilczek and Allium cepa L. bio-indicators. A novel Gas Chromatography Mass Spectroscopy (GC-MS) method was developed, and a reduction in toxic organic compounds was observed, with ester, phenol, furan, and pentacyclic compounds being transformed into stable aromatic compounds during the composting process. The developed novel method could be used globally for identifying toxic organic compounds in compost samples.