Environmental Studies Department, University of California, Santa Cruz, 1156 High St., Santa Cruz, California 95064, United States.
Life and Environmental Sciences Unit, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343, United States.
Environ Sci Technol. 2020 Apr 7;54(7):4545-4553. doi: 10.1021/acs.est.9b05377. Epub 2020 Mar 23.
California's landmark waste diversion law, SB 1383, mandates the diversion of 75% of organic waste entering landfills by 2025. Much of this organic waste will likely be composted and applied to farms. However, compost is expensive and energy intensive to transport, which limits the distance that compost can be shipped. Though the diversion of organic waste from landfills in California has the potential to significantly reduce methane emissions, it is unclear if enough farmland exists in close proximity to each city for the distribution of compost. To address this knowledge gap, we develop the Compost Allocation Network (CAN), a geospatial model that simulates the production and transport of waste for all California cities and farms across a range of scenarios for per capita waste production, compost application rate, and composting conversion rate. We applied this model to answer two questions: how much farmland can be applied with municipal compost and what percentage of the diverted organic waste can be used to supplement local farmland. The results suggest that a composting system that recycles nutrients between cities and local farms has the potential to play a major role in helping California meet SB 1383 while reducing state emissions by -6.3 ± 10.1 MMT COe annually.
加利福尼亚州具有里程碑意义的废物转移法规 SB 1383 要求到 2025 年将进入垃圾填埋场的 75%有机废物转移。这些有机废物中的大部分可能会被制成堆肥并应用于农场。然而，堆肥的运输成本高昂且能源密集，这限制了堆肥的运输距离。虽然从加利福尼亚州的垃圾填埋场转移有机废物有潜力显著减少甲烷排放，但尚不清楚每个城市附近是否有足够的农田来分配堆肥。为了解决这一知识差距，我们开发了堆肥分配网络 (CAN)，这是一个地理空间模型，可模拟加利福尼亚州所有城市和农场的废物生产和运输，涵盖了人均废物产量、堆肥应用率和堆肥转化率的一系列情景。我们应用该模型回答了两个问题：可以用城市堆肥覆盖多少农田，以及可以使用多少转移的有机废物来补充当地农田。结果表明，在城市和当地农场之间回收养分的堆肥系统有可能在帮助加利福尼亚州实现 SB 1383 的同时，通过每年减少 6.3±10.1 兆吨二氧化碳当量来发挥主要作用。
