Comparison between cold plasma, ultrasonication, and alkaline hydrogen peroxide pretreatments of garden waste to enhance humification in subsequent composting with kitchen waste: Performance and mechanisms

This study compared the performance and mechanisms of cold plasma, ultrasonication, and alkali-assisted hydrogen peroxide for garden waste pretreatment to advance humification in composting with kitchen waste. High-throughput sequencing integrated with Functional Annotation of Prokaryotic Taxa was used to relate bacterial dynamics to humification. Results show that all pretreatment techniques accelerated humification by 37.5% - 45.7% during composting in comparison to the control treatment. Ultrasonication and alkalization preferred to decompose lignocellulose to produce humus precursors in garden waste, thereby facilitating humus formation at the beginning of composting. By contrast, cold plasma was much faster and simpler than other pretreatment techniques to effectively disrupt the surface structure and reduce the crystallinity of garden waste to enrich functional bacteria for aerobic chemoheterotrophy, xylanolysis, cellulolysis, and ligninolysis during composting. As such, a more robust bacterial community was developed after cold plasma pretreatment to advance humification at the mature stage of composting.