Occurrence and environmental levels of triclosan and triclocarban in selected wastewater treatment plants in Gauteng Province, South Africa

Abstract

Triclosan and triclocarban are industrial chemicals that are frequently added into consumer and personal care products. Information on the levels on these compounds in water systems in the African continent is still very scarce. In the present study, the occurrence, seasonal variation, and estimated removal of TCS and TCC in six different wastewater treatment plants in Gauteng Province, South Africa, were investigated over a period of two years, together with effluent receiving river water. The instrumental analysis was carried out using Shimadzu LCMS/MS 8030, employing negative electrospray ionization. Both target compounds were ubiquitously detected with influent and raw sludge having elevated concentrations. Generally, TCS concentrations were higher than those of TCC. The concentrations obtained for TCS were (influent, 2.01–17.6 μg/L; effluent, 0.990–13.0 μg/L; river, 0.880–8.72 μg/L; raw sludge, 3.65–15.0 μg/kg; treated sludge, 2.08–7.81 μg/kg and biosolids, 2.16–13.5 μg/kg); while TCC levels were obtained to be (influent, 0.0860–2.84 μg/L; effluent, <LOD - 1.89 μg/L; river, nd - 0.360 μg/L; raw sludge, 3.65–11.8 μg/kg; treated sludge, 1.21–9.19 μg/kg; biosolids, 2.59–8.23 μg/kg). Occurrence of TCS in wastewater was found to be influenced by temporal changes. This was not the case for occurrence of TCS and TCC in sludge samples. Similar to their environmental occurrence, the estimated treatment efficiencies also varied across the wastewater treatments plants, with the highest elimination rates of 63% and 97% for TCS and TCC, respectively.