Production of synthetic fertilizers is energy-intensive and unsustainable, whereas urine-derived fertilizers (UDFs) are a sustainable alternative. Urine diversion can reduce the energy requirements of fertilizer production while recovering nutrients from municipal wastewater streams and reducing water pollution. It is important to reduce the risk to public health from chemical (pharmaceuticals) and microbiological (bacteria and virus) contaminants before UDFs are applied. Advanced oxidation processes (AOPs) like ozone and UV/hydrogen peroxide can achieve near complete degradation of many pharmaceuticals, predominantly through the production of hydroxyl radicals. AOP may reduce risks for both chemical and biological contaminants that are not otherwise removed by UDF processing methods that target nutrient recovery. Plasma is a promising method of applying AOP during UDF processing because it can produce ozone, hydroxyl radicals, hydrogen peroxide and other radical species simultaneously, making it a highly efficient AOP.<br/><br/>For this presentation, we will determine the energy efficiency, pharmaceutical degradation rate and stoichiometry, and production of transformation products during plasma treatment of urine. Previous research on plasma oxidation of pharmaceuticals focused on the degradation of organic compounds in Millipore water. Synthetic urine has high conductivity and high organic concentration, which will affect the production of plasma and hydroxyl radicals. A dielectric barrier discharge plasma jet configuration has been constructed and tested for the production of plasma in synthetic urine. We have generated plasma using compressed air with our device and are modifying it for our next experiments with synthetic urine. The steady state concentration of hydroxyl radicals will be characterized with methylene blue. The potential for background scavenging of hydroxyl radicals is being determined using fluorescein and tert-butanol. We will use pharmaceuticals for this study that cover a broad range of chemical characteristics, similar to past work by our group. The concentration of pharmaceuticals and their transformation products will be quantified with an Orbitrap LC-MS/MS, for which we are currently resolving methods. Understanding pharmaceutical degradation and transformation product formation during plasma treatment will allow us to assess its potential as an AOP technology as part of a series of processing steps to generate UDFs.

Transformation of pharmaceuticals during dielectric barrier discharge plasma jet treatment in synthetic urine

255th National Meeting (2018)

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