Effectiveness of conventional wastewater treatment processes in removing pharmaceutically active compounds

Limited work has been done to assess the types and levels of PACs in domestic and treated wastewater in arid and semi-arid countries. In these countries, reuse or artificial recharge of treated sewage effluent is commonly practiced. Thus, the objectives of this study were to quantify the levels of selected PACs in domestic wastewater in the United Arab Emirates (UAE) and to assess the effectiveness of domestic wastewater treatment plants in their removal. An analytical protocol was developed for the analysis of 15 PACs using a UPLC-MS/MS system. Four batches of water and sludge samples were collected from different locations at Al Saad Wastewater Treatment Plant in Al Ain, UAE. Aliquots of each sample were enriched by solid phase extraction. Results show that phenylephrine, dapsone, noscapine, propyl gallate, genistein, and ketoconazole were present in the raw wastewater at low levels (<0.1 μg/L), while acetaminophen and caffeine were present at high levels (>10 μg/L). The overall removal efficiency of the tested PACs from the water stream exceeded 99% for cotinine, acetaminophen, caffeine, naproxen, and ibuprofen, but significantly drops (<50%) for phenylephrine, amoxicillin, dapsone, noscapine, spiramycin, noscapine, genistein and ketoconazole. Analysis of the results indicate that, for highly removed PACs, the main mechanism of removal is possibly aerobic biodegradation. However, for tyramine, dapsone, 9-aminoacridine, noscapine, propyl gallate, and ketoconazole sorption onto the mixed liquor suspended solids first occurs followed by removal by anaerobic digestion. Results of the study should be useful for properly managing treated sewage effluent and sewage sludge.