Carbon and N conservation during composting: A review

Composting, as a conventional solid waste treatment method, plays an essential role in carbon and nitrogen conservation, thereby reducing the loss of nutrients and energy. However, some carbon-and nitrogen-containing gases are inevitably released during the process of composting due to the different operating conditions, resulting in carbon and nitrogen losses. To overcome this obstacle, many researchers have been trying to optimize the adjustment parameters and add some amendments (i.e., pHysical amendments, chemical amendments and microbial amendments) to reduce the losses and enhance carbon and nitrogen conservation. However, investigation regarding mechanisms for the conservation of car-bon and nitrogen are limited. Therefore, this review summarizes the studies on physical amendments, chemical amend-ments and microbial amendments and proposes underlying mechanisms for the enhancement of carbon and nitrogen conservation: adsorption or conversion, and also evaluates their contribution to the mitigation of the greenhouse effect, providing a theoretical basis for subsequent composting-related researchers to better improve carbon and nitrogen conser-vation measures. This paper also suggests that: assessing the contribution of composting as a process to global greenhouse gas mitigation requires a complete life cycle evaluation of composting. The current lack of compost clinker impact on car-bon and nitrogen sequestration capacity of the application site needs to be explored by more research workers.

Automated summary

Composting plays a crucial role in carbon and nitrogen conservation, but losses of carbon and nitrogen still occur during the process. Researchers have explored ways to reduce these losses and enhance conservation through amendments, and proposed potential mechanisms for conservation. Evaluating the contribution of composting requires a comprehensive assessment, and the impact of compost clinker on carbon and nitrogen sequestration capacity needs further investigation.