A nationwide survey and emission estimates of cyclic and linear siloxanes through sludge from wastewater treatment plants in Korea

• Published in: The Science of the total environment Vol. 497-498; pp. 106 - 112
• Main Authors: Lee, Sunggyu, Moon, Hyo-Bang, Song, Geum-Ju, Ra, Kongtae, Lee, Won-Chan, Kannan, Kurunthachalam
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-11-2014
• Subjects: Decamethylcyclopentasilane; Dodecamethylcyclohexasilane; Emission flux; Personal care products; Republic of Korea; Sewage - chemistry; Siloxanes - analysis; Waste Disposal, Fluid; Waste Water - chemistry; Wastewater; Water Pollutants, Chemical - analysis; WWTP; Republic of Korea; Personal care products; Decamethylcyclopentasilane; WWTP; Wastewater; Dodecamethylcyclohexasilane; Emission flux
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2014.07.083

Siloxanes are widely used in various industrial applications as well as in personal care products. Despite their widespread use and potential toxic effects, few studies have reported on the occurrence of siloxanes in the environment. In this study, we determined the concentrations of 5 cyclic and 15 linear siloxanes in sludge collected from 40 representative wastewater treatment plants (WWTPs) in Korea. Total concentrations of 20 siloxanes (Σsiloxane) in sludge ranged from 0.05 to 142 (mean: 45.7) μg/g dry weight, similar to the concentrations reported in European countries but higher than those reported in China. The concentrations of siloxanes in sludge from domestic WWTPs were significantly (p<0.01) higher than those from industrial WWTPs, indicating higher consumption of siloxanes in various personal care products (e.g. shampoos and conditioners). The major siloxane compounds found in sludge were decamethylcyclopentasilane (D5), docosamethyldecasiloxane (L10) and dodecamethylcyclohexasilane (D6), which collectively accounted for, on average, 62% of the Σsiloxane concentrations. Non-parametric multidimensional scaling ordination of the profiles of siloxanes indicated the existence of different usage patterns of siloxanes between industrial and household activities. Multiple linear regression analysis of siloxane concentrations and WWTP characteristics suggested that D5, D6 and linear siloxane concentrations in sludge were positively correlated with population served by a WWTP. Environmental emission fluxes of cyclic and linear siloxanes through sludge disposal in Korea were 14,800 and 18,500kg/year, respectively. This is the first report describing occurrence and environmental emission of siloxanes through sludge in Korea.
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•Highest levels of siloxanes were found in domestic WWTP sludge from Korea.•Compositional profiles of siloxanes varied domestic and industrial WWTP sludge.•The nationwide emission flux of siloxanes via sludge discharge was estimated.•Population-served is a determinant of siloxanes in sludge from WWTPs.