- Finding renewable sources of agricultural fertilizer will be necessary to ensure a stable food supply for future generations. Phosphorus is of particular concern, since mining phosphate rock is the main source and reserves are forecasted to deplete in the next 50 – 200 years. Human urine contains substantial amounts of nitrogen, phosphorus, and potassium. The value of urine as fertilizer is enhanced since the supply is nearly geographically ubiquitous, allowing for localized sourcing and treatment. Urine from the general population typically contains residual unmetabolized pharmaceuticals. Previous studies collected urine from human populations and found common pharmaceuticals on the order of tens to hundreds of micrograms per kilogram of urine, on average. Using urine as fertilizer for vegetables causes significant amounts of some drugs to be taken up into the edible parts of plants. Degradation of pharmaceuticals in human urine makes the urine a more feasible and accepted source of fertilizer. In this study, a 3D-printed miniature reactor which could be deployed in the field was created to demonstrate UV-degradation of pharmaceuticals. Possessing a well-characterized UV-visible spectrum, acetaminophen was the representative pharmaceutical selected for degradation in this study.
Batch and continuous flow reactors degraded acetaminophen using 254 nm artificial light. A continuous flow reactor was designed, 3D printed, and constructed. Acetaminophen photolysis was measured at an array of light intensities and flow rates through the reactor. Inlet concentrations of 2.5 and 5 ppm acetaminophen were tested. The amount of acetaminophen degraded through the reactor grew with increasing residence time and light intensity. Up to 80% of the acetaminophen was degraded in the continuous flow trials. Data was comparable to MFR and PFR models. These ideal models were fit to the data to determine pseudo-first order rate constants for photolysis.
Key Words: UV photolysis, 254 nm light, acetaminophen, pharmaceuticals in urine, 3D printing, microreactor
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- Key Words: UV photolysis, 254 nm light, acetaminophen, pharmaceuticals in urine, 3D printing, microreactor