Fate of Octyl- and Nonylphenol Ethoxylates and Some Carboxylated Derivatives in Three American Wastewater Treatment Plants

Abstract

The fate of a comprehensive group of nonylphenol and octylphenol ethoxylates (APEOs) and several of their carboxylated derivatives was studied in three American wastewatertreatment plants (WWTPs), two of which included advanced treatment. Influent and effluent concentrations of the alkylphenolic compounds (APEs) in the three plants were very similar, but effluent concentrations showed a seasonal dependency: both carboxylate and ethoxylate concentrations in the effluents were higher in winter than in summer. Sorption to particulate matter was higher for nonylphenolic compounds than for their octylphenolic counterparts, in agreement with their difference in Kow values. Both effluent concentrations and the removal efficiency of the APEOs were strongly correlated to water temperature, but no correlation was found with suspended solids or organic carbon removal. Although APEO removal from wastewater was high, overall removal from the WWTPs, including APEOs in waste sludge and transformation products, was relatively low and suggested that advanced treatment does not invariably result in better APEO removal. Additionally, a survey of urban sewers suggested that household products still constitute an important source of the APEOs reaching WWTPs.

Fate of nonylphenol polyethoxylates and their metabolites in four Beijing wastewater treatment plants

“…It is clear that the total concentrations of nonylphenolic compounds (NP-c) in the dry weather is related to industrial and domestic wastewater content in the WWTPs influents, i. e., 0.115 to 0.183 μmol/L of NP-c in the WWTPs receiving both industrial and domestic wastewaters, and 0.347 μmol/L of NP-c in the WWTP receiving only domestic wastewater. The concentrations of nonylphenolic compounds detected in this study fell into the range reported in other literatures (Ma et al, 2002;Planas et al, 2002;Hou and Sun, 2006;Stasinakis et al, 2008), but were at low level compared to those observed in the European countries, such as Switzerland (2.42-4.05 μmol/L) (Ahel et al, 1994) and United States (425-894 μg/L for NP0-16EO) (Loyo-Rosales et al, 2007), indicating that the contamination in Beijing seemed less heavy than abroad, probably due to less consumption of NPnEOs surfactants in Beijing.…”

“…Regarding the effluents of WWTPs, NPECs were as expected the most abundant group (Fig. 1b), indicating NPECs were the main metabolites of NPnEOs during biological degradation processes (Ahel et al, 1994;Loyo-Rosales et al, 2007).…”

“…As mentioned by a report (Loyo-Rosales et al, 2007), samples were considered as "the summer" if water temperature was above 20°C and as "the winter"if it was below 15°C. The total concentrations of nonylphenolic compounds in the influents and removal of NPnEOs (n ≥ 3) in the summer and the winter for plant 2 and plant 3 were illustrated in Fig.…”

“…However, most of the reports limited the number of analytes to NP and NPnEOs, while only a few reports included NPECs and CAPECs (Ahel et al, 1994;Corcia et al, 2000;Fujita et al, 2000;Loyo-Rosales et al, 2007). Especially in China, there has been no data for NPECs in WWTPs up to date.…”

“…Moreover, despite the existence of several studies investigating the presence of nonylphenolic compounds in WWTPs, most of them focused exclusively on concentrations in influents and effluents (Ma et al, 2002;Shao et al, 2003;Hao, 2007), and then removal efficiencies were obtained. Only a few reports have made mass balance of nonylphenolic compounds in WWTPs to obtain the output pathways of nonylphenolic compounds (Ahel et al, 1994;Bruno et al, 2002;Loyo-Rosales et al, 2007). Moreover, the contributions of the pathways were rarely determined probably due to the difficulty in detecting all the nonylphenolic compounds in wastewater and sludge samples and in getting accurate operational parameters of WWTPs.…”