priority organic pollutants regulated under U.S. drinking water standards as well as additional compounds of concern. The organic analytes evaluated by San Diego included 62 volatile organic compounds; 68 semivolatile organic compounds, including trihalomethanes, benzene, N nitrosamines, chlorinated aromatics, phenols, and polynuclear aromatic hydrocarbons; pesticides and polychlorinated biphenyls (PCBs); chlorinated dibenzodioxins/dibenzofurans; and low molecular weight aldehydes (Western Consortium for Public Health, 1997). Concentrations of all regulated contaminants were below U.S. and state drinking water standards. Similar evaluations of organic chemicals, with similar results, were conducted at Tampa (CH2M Hill, 1993) and Denver (Lauer et al., 1991).

The Denver reuse project conducted an organic challenge study in which 15 different organic compounds were dosed at approximately 100 times the normal levels found in the reuse plant influent (Lauer et al., 1991). Table 2-3 shows the initial doses and removal rates of these compounds for four different treatment processes. Five of the compounds were removed completely (i.e., to below detectable limits) by lime treatment, and eight of the remaining ten were removed completely by the granular activated-carbon filters. The reverse-osmosis membranes allowed 1.1 mg/liter of chloroform to pass through; this chloroform was subsequently removed by air stripping. The study showed that even

TABLE 2-3 Reuse Plant Organic Challenge Study (cumulative % removals)

Compound

Initial Dose (mg/liter)

Lime

Carbon

Reverse Osmosis

Plant Effluent

Acetic acid

5054

100

Anisole

23

100

Benzothiazole

86.2

63

100

Chloroform

229.6

26

99.7

99.9

100

Clofibric acid

17.1

0

100

Ethyl benzene

25.1

100

Ethyl cinnamate

67.8

100

Methoxychlor

44.6

84

100

Methylene chloride

230

8

100

Tributyl phosphate

69.4

51

100

Toluenea

 

25

97

100

Benzenea

 

40

100

Ethylbenzenea

 

36

100

Xylenea

 

32

100

aDosed as 2115 mg/liter of gasoline.

SOURCE: Modified from Lauer et al., 1991.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement