Evaluation of silver nanoparticle-fortified biochar as a reactive filter media for irrigation water disinfection
Date
2019
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Publisher
University of Delaware
Abstract
Despite increased governmental efforts, foodborne illnesses persist as a major risk to public health in the United States. With increasing demand for fresh vegetables and produce, contaminated crops are one of the most common sources of foodborne illnesses. One common crop contamination pathway is contaminated irrigation water. In an effort to combat the issue of foodborne illnesses, the U.S. Food and Drug Administration introduced new regulations targeting the food production industry, including a stricter law regarding the allowable amount of bacteria in irrigation water. Given these regulations and increasing water scarcity due to climate change, it is imperative that farmers have a simple and reliable way to treat their irrigation water. ☐ This work focuses on the removal of Escherichia coli from irrigation water using a novel water treatment media, silver-amended soil reef biochar (Ag/SRB). Biochar is produced from pyrolyzed organic waste and has been used in water treatment applications for chemical removal and transformation. Through addition of silver, Ag/SRB can significantly reduce microbial concentrations in water, unlike plain biochar. Experiments were conducted to assess Ag/SRB’s ability to reduce E. coli cell concentrations under batch system conditions and were compared with batch inactivation experiments using AgNO₃-derived silver ion (Ag+). It was determined that 0.1 g/L and 1 g/L Ag/SRB could remove 1.5 log and 3 log of E. coli, respectively, following 30 minutes of contact time. Ag+ measurements were taken during Ag/SRBbatch experiments and the predicted inactivation rates given the Ag+ concentrations were comparable to the results of the Ag+ inactivation experiments. Ag/SRB was also used in a flow-through column system and compared with unamended biochar. With a retention time of two minutes, Ag/SRB was able to remove 0.75 log of E. coli from an E. coli spiked wastewater effluent. These results demonstrate that Ag/SRB has the potential to be an effective irrigation water treatment media. ☐ Future research should focus on studying the longevity of Ag/SRB and how removal performance changes over time. Different flow rates and water matrices should also be explored to assess potential effects on Ag/SRB’s performance.
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Keywords
Biochar, E. coli, Nanoparticles, Silver, Water treatment