Determination of the effect of active exposure to low-frequency ultrasonic field for the removal of pharmaceutical residues from sewage sludge using liquid chromatography

Pharmaceuticals are usually only partially metabolised; they end up in wastewater treatment plants (WWTP), where their large are insufficiently removed by conventional technological systems and thus can be released into the environment. Using technology based on exposure to an ultrasonic field as a disintegrating factor affects the change in the concentration of the pharmaceuticals tested, contributing to their decomposition. This solution can be considered an effective method supporting the conventional removal of micropollutants, including pharmaceutical residues in sewage sludge. The primary research was conducted at the Faculty of Infrastructure and Environment, Częstochowa University of Technology. It aimed to determine the possibility of degradation of selected pharmaceuticals using an ultrasonic field (UF) with a frequency of 20 kHz, with exposure as a disintegrating factor. Based on the examinations, i.e. quantitative analysis, the distribution of the studied groups of micropollutants caused by this process was determined. The greatest susceptibility to decomposition induced by exposure to the ultrasonic field was found for sulfamethoxazole, with an approximately 100 % reduction in concentration for a sonication time of 60 seconds. Satisfactory results were also obtained for three non-steroidal anti-inflammatory drugs (NSAIDs) and carbamazepine, with a decrease in their concentration recorded for 180 s of preparation, proving their significant susceptibility to degradation due to complex sonochemical reactions. In the case of a preparation time of 180 s and with respect to the concentration reduction, the NSAIDs can be arranged in the following series: ketoprofen ˃ ibuprofen ˃ diclofenac. In the case of a preparation time of 180 s and in relation to the susceptibility to degradation, the NSAIDs can be arranged in the following series: ketoprofen ˃ ibuprofen ˃ diclofenac. For the above-mentioned compounds, the concentration reduction was as follows: 63 %, 48 %, and 40 %, with 69 % for carbamazepine. However, the variable trend for the decrease in the concentration of metoprolol and propranolol observed with the increase of the sonication time indicates the organic susceptibility of the above pharmaceutical residues to decomposition in the ultrasonic field.