Abstract
This study investigates the presence of new psychoactive substances (NPS) and their metabolites in two wastewater treatment plants (WWTPs) situated in South Wales, UK (WWTP-1 and WWTP-2). Analysis was conducted for 35 NPS and metabolites, along with the inclusion of benzoylecgonine (main cocaine metabolite) and cannabis, the most detected illicit substances. Benzoylecgonine was identified as the predominant substance in both WWTPs. Epidemiological calculations revealed the average population consumption of cocaine to be 3.88 mg/d/1000 inhabitants around WWTP-1 and 1.97 mg/d/1000 inhabitants for WWTP-2. The removal efficiency of benzoylecgonine across both WWTPs was observed at an average of 73%. Subsequent qualitative analyses on randomly selected wastewater samples detected medicinal compounds including buprenorphine, methadone, and codeine in both WWTPs. An additional experiment employing enzymatic hydrolysis revealed the presence of morphine, an increased presence of codeine, and 11-Nor-9-Carboxy-THC (THC-COOH) post-hydrolysis. These findings underscore the significant presence of illicit substances and medicinal compounds in wastewater systems with the absence of NPS within the South Wales area, highlighting the necessity for enhanced monitoring and treatment strategies to address public health and environmental concerns.