Transport and behavior of nonylphenol ethoxylates in a full-scale municipal wastewater treatment plant

To study the transport and behaviour of short chain nonylphenol ethoxylates (NP _nEO, n=1, 2) in anoxic/oxic (A/O) process of municipal wastewater treatment plant, the distribution of short chain NP _nEO and NP in the aqueous phase and sludge of each unit process in a full-scale municipal wastewater treatment plant of northeast China were investigated using a solid phase extraction-gas chromatography-mass spectrometry (SPE-GC-MS). The results showed that the influent NP, NP ₁EO and NP ₂EO were 1973, 1784 and 891 ng/L, which were lower than those of other cities in China and many other countries, then the concentrations of three compounds increased and reached to the highest at aeration grit chamber due to the biodegradation of long chain NP _nEO, which were 3326, 4228 and 2066 ng/L, respectively, after that the concentrations of them were dropping down significantly at anaerobic sink because of the adsorption of activated sludge, and finally the effluent NP, NP ₁EO and NP ₂EO were 351, 328 and 159 ng/L. It is concluded that the anaerobic sink made more contribution for the removal of these compounds in influent. In addition, the concentrations of NP, NP ₁EO and NP ₂EO in each treatment unit have a positive correlation with their TOC content.