Microplastics in household fecal sewage treatment facilities of rural China

Fecal sewage (FS), composed of human feces and wastewater, potentially contains microplastics (MPs) that are prone to environmental pollution. In this study, 65 FS samples, as collected from 65 villages in 27 Chinese provinces, have been employed to investigate the characteristics of MPs in three kinds of household FS treatment facilities of rural regions, and the possibility of FS irrigation as the source of MPs in farmlands. As a result, seven physicochemical properties and microbial community of FS were detected, and pertinent social statistical data were collected to determine influencing factors of MPs. The abundance of FS-based MPs ranged from 47.16 to 143.05 particles L^-1, with an average 90.38 ± 20.63 particles L^-1. The FS from northern China had higher MPs abundance than that from southern and northwestern China. Average MPs abundance was cesspit (101.33) > septic tank (86.54) > biogas digester (84.11). The estimated mass of FS-based MPs entering farmlands in China was 7.8 × 10³-5.6 × 10⁴ tons a year. Chemical oxygen demand and genus Phascolarctobacterium might mainly affected MPs abundance in FS, while some other factors such as suspended substance, ambient temperature, and medical care spending were also significantly correlated with FS-based MPs abundance.