Abstract
This is the first study dealing with removal of the pharmaceutical substances in municipal wastewater treatment plants (MWWTPs) from Peru and the impact of these compounds in surface waters receiving treated wastewater. To this aim, samples from MWWTP of Lima (Peruvian Coast), MWWTP of Cusco, Puno and Juliaca (Peruvian Highlands), as well surface water (confluence of Torococha and Coata rivers in Juliaca) were analyzed. A total of 38 target pharmaceuticals were included in this study and were determined by Liquid Chromatography coupled to tandem Mass Spectrometry (LC-MS/MS). Around 60% and 75% of the target pharmaceuticals could be quantified in surface water and MWWTPs, respectively. Acetaminophen was the drug found at the highest concentration, and it was present in all the treated wastewater samples reaching average values above 100 μg/L in the department of Puno. The gabapentin anti-epileptic drug (up to 11.85 μg/L in MWWTP Lima) and the antibiotics clarithromycin, trimethoprim, ciprofloxacin, sulfamethoxazole and azithromycin (1.86 to 4.47 μg/L in MWWTP Lima) were also found at moderate concentrations in the treated wastewater. In surface water, the highest concentration corresponded also to acetaminophen (28.70 μg/L) followed by sulfamethoxazole (4.36 μg/L). As regards the pharmaceuticals removal, data of this work showed that the MWWTP Cusco (aerobic biologic process by synthetic trickling filters as secondary treatment) was more efficient than the MWWTP Lima (a preliminary treatment that combines grilles, sand trap, degreaser-aerated and sieved of 1.0 mm). However, many pharmaceuticals (around 50% of the compounds investigated) presented concentrations in treated wastewater similar or even higher than in influent wastewater. The environmental ecological risk of pharmaceuticals was assessed based on calculated Risk Quotient (RQ) in the treated wastewater and surface water from the concentration data found in the samples. According to our data, three antibiotics (clarithromycin, ciprofloxacin, clindamycin) and the analgesic acetaminophen posed high environmental risk (RQ ≥ 1) on the aquatic environment. In the river, all antibiotics (except norfloxacin) as well as the analgesic-anti-inflammatory compounds acetaminophen, diclofenac posed a high environmental risk (RQ ≥ 1). Based on data reported in this work for the first time in water samples from Peru, it can be deduced that the treatment processes applied in important cities from Peru are not enough efficient to remove pharmaceuticals in wastewater. As a consequence, severe environmental risks associated to the presence of pharmaceuticals in treated wastewater and surface water are expected; so complementary treatment processes should be implemented in the MWWTPs for a more efficient elimination of these compounds.
Highlights
Nowadays, the presence of pharmaceutical compounds and their metabolites, considered as emerging organic micropollutants, in the aquatic environment is a major concern worldwide (Couto et al, 2019; Valdez-Carrillo et al, 2020; Pereira et al, 2020a; Pereira et al, 2020b)
The results presented in this paper are the first data reported on Peru, and constitute the initial contribution for a better knowledge on pharmaceutical compounds present in effluent wastewaters, and on the ecotoxicological risk in aquatic ecosystems
Data reported in this work allow to conclude that around 30% of target pharmaceuticals were removed in the Cusco municipal wastewater treatment plants (MWWTPs), with RE > 75%, while in the Lima MWWTP lower RE were obtained for most compounds tested
Summary
The presence of pharmaceutical compounds and their metabolites, considered as emerging organic micropollutants, in the aquatic environment is a major concern worldwide (Couto et al, 2019; Valdez-Carrillo et al, 2020; Pereira et al, 2020a; Pereira et al, 2020b). Within the wide group of pharmaceutical compounds, antibiotics are those of most concern due to the negative impacts that they can generate on aquatic ecosystem and human health, e.g., the development of antimicrobial resistance strains caused through the discharge of waste water to water bodies (Kairigo et al, 2020; Ben et al, 2019). Illustrative of this concern is the inclusion of several pharmaceuticals in the Watch List of European Union (EU), recently updated (EU, 2020). Nine phar maceuticals and one metabolite are included in this list, of which four are antibiotics (Amoxicillin, Ciprofloxacin, Sulfamethoxazole, Trimethoprim)
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