From generation to treatment: A systematic reactive nitrogen flow assessment of solid waste in China

The continuously increasing amount of solid waste (SW) that is being generated in China calls for environmental assessment and management strategies. However, the pattern and magnitude of the reactive nitrogen (Nr) loss associated with SW have received negligible attention. Here, we established a systematic Nr flow assessment of the generation, treatment and emissions of SW in China from 1978 to 2015. The Nr flow of SW increased by 87% during this period, with the livestock sector being the largest contributor. Composting and animal feed were the two main methods of SW treatment, accounting for more than half, whereas the two fastest growing treatments were remanufacturing and sewage treatment, which increased 13- and 62-fold, respectively. Each SW treatment method would inevitably lead to Nr emissions. Our results showed that the total Nr emissions from SW treatment increased from 8.7 Tg N yr(-1) in 1978 to 18.6 Tg N yr(-1) in 2015. The development of sustainable SW management requires considering both economic and environmental impacts. We use an optimization model (Solid Waste Optimization Life-Cycle Framework) and provide evidence that recycling SW resources will be an option for economic and environmental trade-offs. (C) 2020 Published by Elsevier Ltd.