Post-Graduation Programme in Animal Biology Behaviour and Ecology (PGECOL), Institute of Biological Sciences, Federal University of Juiz de Fora, Rua José Lourenço Kelmer, s/n, Sao Pedro, Juiz de fora CEP 36.036-900, Brazil.
Embrapa Dairy Cattle (Brazilian Agricultural Research Corporation - Embrapa), Rua Eugênio do Nascimento, 610, Dom Bosco, Juiz de Fora CEP 36.038-330, Brazil.
Sci Total Environ. 2020 Nov 25;745:140711. doi: 10.1016/j.scitotenv.2020.140711. Epub 2020 Jul 12.
The reuse or recycling of wastewater provides environmental and economic benefits, representing a sustainable and circular alternative for the management of liquid waste. However, the application of effluents to agricultural crops via spraying creates a potentially dangerous situation for individuals exposed to airborne pathogens. This study used Quantitative Microbial Risk Assessment (QMRA) tools to quantitatively assess the microbial risks of occupational and public exposures to bioaerosols in fertigation scenarios by spraying untreated and treated dairy cattle wastewater. Analyses of Escherichia coli (EC) and spores of Clostridium perfringens (CpSP) in raw and treated effluents as well as pathogen / indicator ratios from the literature were used to estimate the concentrations of Escherichia coli O157:H7 (EC O157:H7) and Cryptospodirium spp. (Crypto) in the air, and the results were applied to an atmospheric microbiological dispersion model. From the concentrations of pathogens in the air, infectious risks for downwind receptors were calculated. The risks of infection by EC O157:H7 to workers at 10 m and 50 m away from the emission source ranged between 3.81 × 10 1 and 2.68 × 10 3 pppy (per person per year), whereas to residents at 100 m and 500 m ranged from 4.59 × 10 1 to 1.51 × 10 4 pppy. Peak values (95th percentile) of occupational and public risks associated with the exposure to Crypto were 3.41 × 10 3 and 6.84 × 10 4 pppy at 10 m and 50 m from the source, respectively, and were lower than 1.48 × 10 6 pppy regarding exposures to CpSP. Anaerobic digestion reduced risks by approximately one order of magnitude. The distance from the source was inversely proportional to the risk of exposure. It is recommended that wastewater is treated prior to its reuse and the adoption of application methods with low aerosolization potential. In addition, the need for workers to use personal protective equipment (PPE) is highlighted.
废水的再利用或回收利用具有环境和经济效益，是管理液体废物的可持续和循环替代方案。然而，通过喷洒将废水应用于农业作物会给接触空气中病原体的个人带来潜在的危险情况。本研究使用定量微生物风险评估（QMRA）工具，通过喷洒未经处理和处理后的奶牛废水，对灌溉施肥场景中职业和公众暴露于生物气溶胶的微生物风险进行定量评估。对 raw 和 treated 废水中的大肠杆菌（EC）和梭状芽胞杆菌孢子（CpSP）进行分析，并使用文献中的病原体/指示物比值来估计空气中大肠杆菌 O157:H7（EC O157:H7）和隐孢子虫（Crypto）的浓度，然后将结果应用于大气微生物扩散模型。根据空气中病原体的浓度，计算下风受体的感染风险。距离排放源 10 m 和 50 m 处的工人感染 EC O157:H7 的风险范围为 3.81×10 1 至 2.68×10 3 pppy（每人为每年），而距离排放源 100 m 和 500 m 处的居民的感染风险范围为 4.59×10 1 至 1.51×10 4 pppy。与接触 Crypto 相关的职业和公众风险的峰值（第 95 个百分位）分别为 10 m 和 50 m 处的 3.41×10 3 和 6.84×10 4 pppy，而接触 CpSP 的风险低于 1.48×10 6 pppy。厌氧消化将风险降低了约一个数量级。距离源越远，暴露风险越低。建议在废水再利用之前进行处理，并采用气溶胶化潜力低的应用方法。此外，还强调了工人使用个人防护设备（PPE）的必要性。
