Occurrence and fate of volatile siloxanes in a municipal Wastewater Treatment Plant of Beijing, China

Abstract

a b s t r a c tThe occurrence and fate of four cyclic and two linear volatile siloxanes were studied in a municipal Wastewater Treatment Plant (WWTP), Beijing City, China. Aqueous and sludge samples were analyzed by solid-phase microextraction (SPME) coupled with gas chromatographyemass spectrometry (GCeMS). In the studied WWTP, four cyclic analogs (D3eD6) had significantly higher concentrations and frequencies than the two linear analogs Besides adsorption, they were eliminated mainly in anaerobic units (44.4e84.3%). Through in vitro biodegradation experiments, we concluded that in the anaerobic compartments, Hexamethylcyclotrisiloxane (D3) and Dodecamethylcyclohexasiloxane (D6) were eliminated mostly by volatilization, while Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) may be eliminated by both volatilization and degradation.Furthermore, microbe catalysis hydrolysis was identified as one of the main degradation pathways for D4 and D5 in anaerobic compartments. ª

Understanding the effects of the origin, occurrence, monitoring, control, fate and removal of siloxanes on the energetic valorization of sewage biogas—A review

“…More recently, Xu et al [77] used SPME coupled with GC-MS to determine four c-VMS in aqueous and sludge samples from a WWTP.…”

“…Finally, Xu [77] studied the occurrence and fate of four c-VMS (D3, D4, D5 and D6) and two l-VMS (L3 and L4, concentrations below detection limit) in a municipal WWTP in Beijing (China) in the water and sludge streams. In the WWTP, as shown in Fig.…”

Problemas en el análisis de metilsiloxanos volátiles (VMS): origen y soluciones

“…38 Por otra parte, la técnica del espacio de cabeza también ha sido utilizada conjuntamente con la microextraccción en fase sólida (HS-SPME) para determinar VMS lineales y cíclicos en aguas superficiales. 50,51 La fibra de polidimetilsiloxano/divinilbenceno (PDMS/DVB) ha demostrado tener una mayor capacidad para la adsorción de estos compuestos en comparación a las otras fibras disponibles comercialmente. Este método resulta efectivo para el análisis de agua superficial de río alcanzándose LODs entre 0.01 y 11 ng L -1 para VMS lineales y cíclicos.…”

“…Los disolventes comúnmente utilizados son: n-hexano, n-pentano, acetonitrilo, clorobenceno, y mezclas acetato de etilo/n-hexano y diclorometano/n-hexano [11][12][13]39,44,48,[55][56][57][58][59] . Como alternativa a la extracción con disolvente mediante agitación, también se ha aplicado la extracción asistida por ultrasonidos (UAE) 51,59,60 y la extracción con líquidos presurizados (PLE), 43 sin embargo, estos métodos no son recomendables dado el hecho de que pueden producirse pérdidas de los analitos más volátiles al utilizarse elevadas temperaturas y presión. Debe decirse que de manera general, en los métodos que aplican la extracción con disolventes, se han logrado alcanzar recuperaciones superiores al 70% y LODs entre 0.003 y 37 ng g -1 p.s.…”

Concentrations and distribution of synthetic musks and siloxanes in sewage sludge of wastewater treatment plants in China

“…Siloxane, another class of HPV chemicals, is used not only in a broad range of consumer products, but also in industrial products, such as automotive polishes, fuel additives and anti-foaming agents due to their special properties such as low surface tension, physiologic inertness, high thermal stability and smooth texture (Companioni-Damas et al, 2012;Sanchis et al, 2013;Xu et al, 2012b). The annual production of octamethylcyclotetrasiloxane (D4) is about 45-227 thousand tons, indicating a great potential for widespread presence of siloxanes in the environment (Horii and Kannan, 2008).…”