上海餐厨垃圾处理及有机肥介导的土壤微塑料污染

Microplastic pollution in soil mediated by organic fertilizers derived from kitchen waste treatment in Shanghai

分别以上海黎明资源回用有限公司和上海文鑫生物科技有限公司大型垃圾处理基地为例,研究了餐厨垃圾厌氧和好氧处理过程中产生的微塑料(MPs),并进一步跟踪处理后产生的有机肥产品及其施用后农田土壤中的微塑料,以揭示微塑料的污染特征和环境归趋.结果显示,餐厨垃圾的厌氧和好氧处理过程中均存在微塑料,主要为透明或黑色纤维形状,以小于1 mm尺寸为主,主要成分为聚对苯二甲酸乙二醇酯(PET)和人造丝(Rayon).厌氧处理前样品中微塑料的平均丰度为40.0~546.7 items/kg,而处理后的沼液和沼渣中微塑料的丰度分别显著降低了75.53%和54.41%.好氧处理前的垃圾和稻壳中微塑料的平均丰度分别为53.3~493.3 items/kg和66.7~566.7 items/kg,而处理后的有机肥中微塑料丰度提高了46.84%.施用有机肥的土壤中微塑料的平均丰度达到(176.7±34.8)items/kg,比未施用有机肥的土壤显著提高了137%.这些结果表明,城市餐厨垃圾处理过程可产生微塑料,并能通过有机肥介导加剧土壤微塑料污染.

The occurrence of microplastics(MPs)during anaerobic and aerobic treatment processes of kitchen waste was investigated using case studies from the prominent waste treatment facilities of Shanghai Liming Resources Recycling Co.,Ltd.and Shanghai Wenxin Biotechnology Co.,Ltd.The presence of MPs in the resulting organic fertilizers and the agricultural soils fertilized with these products were further tracked to reveal the pollution characteristics and environmental fate of MPs.Results showed that MPs were present in both anaerobic and aerobic kitchen waste treatment processes,primarily as transparent or black fibers under 1 mm in size and composed predominantly of polyethylene terephthalate(PET)or Rayon.Before anaerobic treatment,the average abundance of MPs in the samples ranged from 40.0 to 546.7 items/kg,whereas,after treatment,the average abundance of MPs in the biogas slurry and biogas residue decreased significantly by 75.53%and 54.41%,respectively.The average abundance of MPs in waste and rice husks before aerobic treatment ranged from 53.3 to 493.3 items/kg and 66.7 to 566.7 items/kg,respectively,whereas,that in organic fertilizers was increased by 46.84%.The average abundance of MPs in the soil with organic fertilizers was(176.7±34.8)items/kg,which was 137%higher than that of the soil without organic fertilizers.These results indicate that MPs can be produced in the process of municipal food waste treatment,and the pollution of soil MPs can be exacerbated through organic fertilizers.