Kearns Joshua, Dickenson Eric, Aung Myat Thandar, Joseph Sarangi Madhavi, Summers Scott R, Knappe Detlef
Aqueous Solutions, Moravian Falls, North Carolina, USA.
Southern Nevada Water Authority, Applied Research and Development Center, Las Vegas, Nevada, USA.
Environ Eng Sci. 2021 May 1;38(5):298-309. doi: 10.1089/ees.2020.0173. Epub 2021 May 24.
Biochar adsorbent can be produced in low-resource settings using local materials and simple pyrolysis technology, and it has shown promise for uptake of micropollutants (MPs) such as pesticides, pharmaceuticals, industrial compounds, and chemicals released from consumer goods present in water at ng/L to μg/L levels. Accordingly, the use of biochar in water treatment applications where granular activated carbon (GAC) is economically or logistically infeasible is gaining interest. Monitoring treatment systems for individual MPs require laboratory analytical techniques that are typically cost-prohibitive and impractical for low-resource settings. Therefore, identification of surrogate parameters(s) for adsorbent bed life that can be measured inexpensively and in the field is a high priority. Background dissolved organic matter (DOM) is ubiquitous in natural and anthropogenic waters at concentrations typically 1,000 to 100,000 that of MPs. Some constituents of DOM foul the adsorbent and reduce bed life for removal of target contaminants. Aromatic DOM foulants absorb ultraviolet light at a wavelength of 254 nm (UVA). Because DOM fouling directly affects MP adsorption capacity and DOM is a bulk water parameter that can be quantified using relatively inexpensive and portable instruments, it could be exploited as a surrogate for monitoring biochar adsorber bed life under field conditions. The objective of this study was to quantify removal of MPs from waters containing different types and concentrations of background DOM (surface water, wastewater, dump leachate) and thus exhibiting different UVA breakthrough profiles in bench-scale column experiments. Breakthrough profiles of weakly to moderately adsorbing MPs, including herbicides, pharmaceuticals and personal care products, and perfluoroalkyl acids, were collected using biochars generated under different pyrolysis conditions and a commercial GAC as a performance benchmark. Optimal conditions for biochar water treatment include using biochar produced from wood at ≥850°C under slightly aerobic conditions, empty bed contact times of ≥30 min, and upstream treatment processes to reduce DOM. Relative UVA breakthrough (/ ) up to 0.6-0.9 corresponded to ≥90% MP removal for most MP-water combinations studied.
生物炭吸附剂可以在资源匮乏地区使用当地材料和简单的热解技术生产，并且它已显示出有潜力去除水中纳克/升至微克/升水平的微量污染物（MPs），如农药、药物、工业化合物以及消费品释放的化学物质。因此，在颗粒活性炭（GAC）在经济或后勤方面不可行的水处理应用中，生物炭的使用正受到越来越多的关注。监测单个MPs的处理系统需要实验室分析技术，而这些技术对于资源匮乏地区来说通常成本过高且不切实际。因此，确定可以在现场廉价测量的吸附剂床寿命替代参数是当务之急。背景溶解有机物（DOM）在天然水和人为水中普遍存在，其浓度通常是MPs的1000到100000倍。DOM的一些成分会使吸附剂 fouling 并缩短去除目标污染物的床寿命。芳香族DOM fouling 在254纳米波长（UVA）处吸收紫外线。由于DOM fouling 直接影响MPs的吸附能力，并且DOM是一个可以使用相对廉价和便携式仪器进行量化的总体水参数，因此它可以作为现场条件下监测生物炭吸附剂床寿命的替代物。本研究的目的是在实验室规模的柱实验中，量化从含有不同类型和浓度背景DOM（地表水、废水、垃圾渗滤液）的水中去除MPs的情况，从而展示不同的UVA突破曲线。使用在不同热解条件下产生的生物炭和商业GAC作为性能基准，收集了弱吸附到中等吸附MPs的突破曲线，包括除草剂、药物和个人护理产品以及全氟烷基酸。生物炭水处理的最佳条件包括使用在≥850°C、略需氧条件下由木材产生的生物炭、空床接触时间≥30分钟以及上游处理工艺以减少DOM。对于大多数研究的MP - 水组合，相对UVA突破（/）高达0.6 - 0.9对应于≥90%的MPs去除率。
