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| Ecological risk assessment of utilization of human excrement resources derived from water-flushing and water-saving public toilets in rural area |
| Received:March 22, 2021 |
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| KeyWord:rural public toilet;feces;heavy metal;antibiotic;ecological risk |
| Author Name | Affiliation | E-mail | | CAI Jiasheng | Key Laboratory of Urban Pollutant Conversion, Chinese Academy of Sciences, Xiamen 361021, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | SHI Jiaozhong | Center of Municipal Public Engineering Construction of Tong' an District, Xiamen 361100, China | | | YE Zhilong | Key Laboratory of Urban Pollutant Conversion, Chinese Academy of Sciences, Xiamen 361021, China | zlye@iue.ac.cn | | LI Yenan | Key Laboratory of Urban Pollutant Conversion, Chinese Academy of Sciences, Xiamen 361021, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | UZMA Shaheen | Key Laboratory of Urban Pollutant Conversion, Chinese Academy of Sciences, Xiamen 361021, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | CHEN Shaohua | Key Laboratory of Urban Pollutant Conversion, Chinese Academy of Sciences, Xiamen 361021, China | |
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| Abstract: |
| Rural public toilet excreta is one of the main sources of organic fertilizer in remote mountainous and barren areas, yet its ecological safety during resource utilization is often ignored. In this study, water-flushing public toilets and water-saving public toilets, the two types of toilet commonly used in the "toilet revolution", were selected for resource potential analysis and ecological risk assessment. The amounts of nutrients and toxic substances(including heavy metals and antibiotics) in excreta were analyzed. The ecological risk index (IR) and hazard quotient(QH) were used to evaluate the potential ecological risks, due to heavy metals and antibiotics residues, respectively, in the utilization of rural public toilet excreta. The results showed that the concentrations of heavy metals in urine/black water were 1.44~895.03 μg·L-1 and 1.04~18 519.34 μg·L-1, the concentrations of heavy metals in compost products/feces were 3.96~3 185.07 mg·kg-1 and 12.43~19 105.59 mg·kg-1; while the concentration of antibiotics in urine/black water was 0~128.13 μg·L-1, and the concentration of antibiotics in compost products/feces was 0~32.32 mg·kg-1. The calculated IR indicated that no ecological risk would occur during the application of urine/black water(IR<150), while the heavy metals in compost products/feces could pose a high ecological risk in land applications(IR ≥ 600). The QH indicated that the oxytetracycline, ofloxacin, and ciprofloxacin contained in urine/black water and compost products/feces might lead to moderate or high ecological risk during land applications(QH>0.1). Compared with feces and black water from water-flushing public toilets, the contents of antibiotics in compost products/urine from water-saving public toilets showed lower ecological risks, indicating that water-saving public toilets were helpful in reducing antibiotic-associated ecological risks. These findings show that heavy metals in compost products(from water-saving public toilets) and feces(from water-flushing public toilets) can cause serious ecological risks during land application, and the water-saving operation of public toilets is conducive to reducing the ecological risks of antibiotics. |
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