Page 84 - Fundamentals of Water Treatment Unit Processes : Physical, Chemical, and Biological

Water Contaminants 39

TABLE 2.A.2
Chlorinated Species Detected by Contact between a Filtered Municipal Secondary Clarifier Effluent
and 2000 mg=L Chlorine
Compound Concentration (mg=L) Compound Concentration (mg=L)

Chloroform — Dichloromethoxytoluene 32
Dibromochloromethane — Trichloromethylstyrene (220) 10
Dichlorobutane 27 Trichloroethyl benzene (208) 12
3-Chloro-2-methylbut-1-ene 285 Dichloro-a-methyl benzyl alcohol (190) 10
Chlorocyclohexane (118) 20 Dichloro-bis(ethoxy)benzene (220) 30
Chloroalkyl acetate — Dichloro-a-methyl benzyl alcohol (190) —
o-Dichlorobenzene 10 Trichloro-N-methylanisole —
Tetrachloroacetone 11 Trichloro-a-methyl benzyl alcohol 25
p-Dichlorobenzene 10 Tetrachlorophenol 30
Chloroethylbenzene 21 Trichloro-a-methyl benzyl alcohol 50
Pentachloroacetone 30 Trichlorocumene (222) —
Hexachloroacetone 30 Tetrachloroethylstyrene —
Trichlorobenzene — Trichlorodimethoxybenzene (240) —
Dichloroethyl benzene 20 Tetrachloromethoxytoluene (258) 40
Chlorocumene — Dichloroaniline derivative (205) 13
N-methyl-trichloroaniline 10 Dichloroaromatic derivative (249) 15
Dichlorotoluene — Dichloroacetate derivative (203) 20
Trichlorophenol — Trichlorophthalate derivative (296) —
Chloro-a-methyl benzyl alcohol — Tetrachlorophthalate derivative (340) —

Source: Glaze, W.H. and Henderson IV, J.E., J. Water Pollut. Control Fed., 47(10), 2511, October 1975.
Notes: Parentheses indicates approximate molecular weights.
Sum of concentrations ¼ 786 mg=L; estimated chlorinated organic compounds 3000–4000 mg=L.

distributions from a sample of water from the Missis- Table 2.A.2; most were aromatic derivatives. Some important
sippi River, given as 0–1,000, 48%; 1,000–25,000, 20%; points are (1) a host of chlorinated organic compounds form
25,000–100,000, 13%; 100,000–1,000,000, 20%; when a secondary effluent is subjected to chlorination, and (2)
>1,000,000, 2% (Tate and Fox, 1990, p. 104). concentrations are in the mg=L range. These compounds
As to the reactions between chloramines and organic car- formed also using a 10 mg=L chlorine dosage.
bon, the TOX production is about the same as that resulting
from chlorine (Johnson and Jensen, 1986). Further, the health
effects of chloramines-treated water are nearly as severe as
those of chlorine-treated water. Thus, while the chloramine
1200
solves the THM problem, it does not solve the health problem
that the THM regulation was intended to address.
1000
TOX
Concentration (μg/L) 600
2.A.3 DISINFECTION BY-PRODUCTS IN SECONDARY 800
EFFLUENTS
A question pertinent to wastewater treatment is the suscepti-
bility of municipal wastewaters to the formation of DBPs. 400 TCAA
Such contaminants could constitute a hazard to aquatic life
CHCl 3
or a problem for downstream drinking water treatment plants. 200
DCAA
Glaze and Henderson (1975) investigated this issue by
‘‘super-chlorinating’’ (defined for their work as 2000 mg=L 0
0 50 100 150 200 250 300
chlorine by gas injection, with 60 min contact time) the
Chlorine contact time (h)
effluent from the secondary clarifiers at the Denton, Texas,
wastewater treatment plant. For reference, 10 mg=L chlorine FIGURE 2.A.2 Chlorination by-products of Black Lake fulvic acid
is a typical dosage of chlorine for wastewaters. as affected by contact time at TOC 4.1 mg=L, pH 7.0, HOCl
Their gas chromatograms showed over 100 peaks with 20 mg=L. (Plotted from data of Reckhow, D.A. and Singer, P.C.,
more than 30 halogenated species detected, identified in J. Am. Water Works Assoc., 76(4), 151, April 1984.)