On-Site Wastewater Treatment and Disposal Systems - Forced ...

TABLE 6-22
CHLORINE DEMAND OF SELECTED DOMESTIC WASTEWATERSa
a Estimated concentration of chlorine consumed in nonspecific
side reactions with 15-minute contact time.
Chlorine
Demand
-Fin---
8 - 15
30 - 45
10 - 25
1 - 5
Iodine is normally used in the elemental crystalline form, I , for water
and wastewater disinfection. Iodine hydrolyzes in water to f arm the hy-
poiodus forms, HI0 and IO’, and iodate, I03. Normally, the predominant
disinfectant species in water are 12, HIO, and IO’, as little IO3 will
be found at normal wastewater pH values (less than pH 8.0). Iodine does
not appear to react very rapidly with organic compounds or ammonia in
wastewaters. As with chlorine, however, most wastewaters will exhibit
an iodine demand due to nonspecific side reactions. The reduced form of
iodine, iodide, which is not an effective disinfectant, is not detected
by iodine residual analyses.
6.5.2.2 Applicability
The halogens are probably the most practical disinfectants for use in
onsite wastewater treatment applications. They are effective against
waterborne pathogens, reliable, easy to apply, and are readily avail-
able.
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