Mass Loading, Removal, and Emission of 1,3-Diphenylguanidine, Benzotriazole, Benzothiazole, N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine, and Their Derivatives in a Wastewater Treatment Plant in New York State, USA

Abstract

1,3-Diphenylguanidine and derivatives (DPGs), benzotriazole and derivatives (BTRs), benzothiazole and derivatives (BTHs), N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), and 6PPD-quinone (6PPD-Q) are rubber additives that are toxic to aquatic organisms. Little is known about their occurrence and fate in wastewater treatment plants (WWTPs) in the United States. We measured the concentrations of 3 DPGs, 7 BTRs, 5 BTHs, 6PPD, and 6PPD-Q in wastewater influent, effluent, suspended particulate matter (SPM), and sludge collected from a WWTP in New York State. Among the four chemical classes analyzed, BTRs were the most predominant in wastewater (median concentration: 6210 and 4380 ng/L in the influent and effluent, respectively), followed by BTHs (184 and 227 ng/L, respectively), DPGs (89.3 and 103 ng/L, respectively), and 6PPDs (17.8 and 8.52 ng/L, respectively). The estimated median mass loadings of DPGs, BTRs, BTHs, and 6PPDs were 77.4, 5330, 165, and 22.7 mg/day/1000 inhabitants, respectively, whereas the corresponding emission rates were 89.9, 3760, 201, and 22.2 mg/day/1000 inhabitants. The removal efficiencies of DPGs, BTRs, BTHs, and 6PPDs in the WWTP were −23.8, 30.9, −76.4, and 29.9%, respectively, indicating ineffective removal during the treatment process. The estimated risk quotients of these chemicals to aquatic organisms through effluent discharge were below 0.1. Further studies are warranted regarding their ecological risks from long-term exposure.