Water quality for agricultural irrigation produced by two municipal sewage treatment plants in Santiago Island-Cape Verde: Assessment of chemical parameters and pharmaceutical residues

Abstract

Cape Verde, a West Africa Island country, is exposed to climate change effect. An effective way of reducing its poverty and achieving food security is to provide its agricultural sector with water. The purpose of this study is to monitor treated water quality to ensure that any pollutants are below the limits set to ensure the safety and sustainability of reuse because only 10% of its treated wastewater is reused. For the first time on Cape Verde islands, besides chemical quality, the occurrence of 11 pharmaceutical compounds (PhC) in the influent and effluent of two natural wastewater treatment plants (WWTPs) was monitored to assess the effectiveness of the treatment technologies and removal efficiencies of these pollutants. Of the 11 target PhC, nine were detected in influent samples within the ng·L−1 to μg·L−1 range. Lower concentrations were detected in one WWTP vs. the other. Nevertheless, the removal efficiencies for most compounds were similar in both WWTPs: within the ranges of 82–92% for beta-blockers, 48–99% for stimulants and 44–95% for nonsteroidal anti-inflammatories, while carbamazepine (anticonvulsant) concentrations increased in effluents. WWTPs produce water that meets water quality standards for irrigation if a properly designed and managed reusing system is adopted.