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Environmental problems - Chemical approaches
RESEARCH ARTICLE

Log DOW: Key to Understanding and Regulating Wastewater-Derived Contaminants

Martha J. M. Wells
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Center for the Management, Utilization, and Protection of Water Resources and Department of Chemistry, Tennessee Technological University, Box 5033, Cookeville, TN 38505, USA. Email: mjmwells@tntech.edu

Environmental Chemistry 3(6) 439-449 https://doi.org/10.1071/EN06045
Submitted: 1 August 2006  Accepted: 1 November 2006   Published: 13 December 2006

Environmental Context. Worldwide, surface water is a source of drinking water and is a recipient of wastewater effluents and pollutants. Many surface water bodies undergo a natural, cyclical, diurnal variation in pH between 7 and 9. Most drinking water and wastewater treatment in the United States is conducted between pH 7 and 8. The pH of water undergoing treatment processes directly impacts the ratio of nonionized to ionized chemical form(s) present, which in turn impacts the success rate of contaminant removal. Many organic wastewater-derived contaminants are very water soluble at pH 7–8 and are inadequately treated.

Abstract. Wastewater-derived contaminants (WWDCs) occur in surface water due to inadequate wastewater treatment and subsequently challenge the capabilities of drinking water treatment. Fundamental chemical properties must be understood to reduce the occurrence of known WWDCs and to better anticipate future chemical contaminants of concern to water supplies. To date, examination of the fundamental properties of WWDCs in surface water appears to be completely lacking or inappropriately applied. In this research, the hydrophobicity–ionogenicity profiles of WWDCs reported to occur in surface water were investigated, concentrating primarily on pharmaceuticals and personal care products (PPCPs), steroids, and hormones. Because most water treatment is conducted between pH 7 and 8 and because DOW, the pH-dependent n-octanol–water distribution ratio embodies simultaneously the concepts of hydrophobicity and ionogenicity, DOW at pH 7–8 is presented as an appropriate physicochemical parameter for understanding and regulating water treatment. Although the pH-dependent chemical character of hydrophobicity is not new science, this concept is insufficiently appreciated by scientists, engineers, and practitioners currently engaged in chemical assessment. The extremely hydrophilic character of many WWDCs at pH 7–8, indicated by DOW (the combination of KOW and pKa) not by KOW of the neutral chemical, is proposed as an indicator of occurrence in surface water.

Keywords. : organic matter — pollutants — water analysis — water treatment


Acknowledgements

Assistance from Susana Harwood, Amy Knox, Sandra Pigg and anonymous reviewers is gratefully acknowledged.


References


[1]   D. W. Kolpin, E. T. Furlong, M. T. Meyer, E. M. Thurman, S. D. Zaugg, L. B. Barber, H. T. Buxton, Environ. Sci. Technol. 2002, 36,  1202.
        | Crossref |  GoogleScholarGoogle Scholar |  (verified 2 November 2006).

[3]   T. A. Ternes, Water Res. 1998, 32,  3245.
        | Crossref |  GoogleScholarGoogle Scholar |  
         
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
         
        | Crossref |  GoogleScholarGoogle Scholar |  
         
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  (verified 2 November 2006).

[20]   C. T. Jafvert, J. C. Westall, E. Grieder, R. P. Schwarzenbach, Environ. Sci. Technol. 1990, 24,  1795.
        | Crossref |  GoogleScholarGoogle Scholar |  (verified 2 November 2006).

[24]   L. J. Fono, D. L. Sedlak, Environ. Sci. Technol. 2005, 39,  9244.
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  
        | Crossref |  GoogleScholarGoogle Scholar |  (verified 2 November 2006).