Environmental Engineering Reference
In-Depth Information
Note:
Ozone has certain advantages over chlorine for the disinfection
of wastewater: (1) ozone increases dissolved oxygen in the effluent, (2)
ozone has a briefer contact time, (3) ozone has no undesirable effects on
marine organisms, and (4) ozone decreases turbidity and odor.
9.5 broMine Chloride
Bromine chloride is a mixture of bromine and chlorine. It forms
hydrocarbons and hydrochloric acid when mixed with water. Bromine
chloride is an excellent disinfectant that reacts quickly and normally
does not produce any long-term residuals.
Note:
Bromine chloride is an extremely corrosive compound in the pres-
ence of low concentrations of moisture.
The reactions occurring when bromine chloride is added to the
wastewater are similar to those occurring when chlorine is added. The
major difference is the production of bromamine compounds rather than
chloramines. The bromamine compounds are excellent disinfectants
but are less stable and dissipate quickly. In most cases, the bromamines
decay into other, less toxic compounds rapidly and are undetectable in
the plant effluent. The factors that affect performance are similar to
those affecting the performance of the chlorine disinfection process.
Effluent quality, contact time, etc. have a direct impact on the perfor-
mance of the process.
9.6 no disinfeCTion
In a very limited number of cases, treated wastewater discharges
without disinfection are permitted. These are approved on a case-by-
case basis. Each request must be evaluated based on the point of dis-
charge, the quality of the discharge, the potential for human contact,
and many other factors.
9.7 ChaPTer revieW QuesTions
9.1
Name one factor that affects the performance of the ultraviolet
irradiation process.
9.2
Explain the difference between disinfection and sterilization.
9.3
To be effective enough, chlorine must be added to satisfy the
and produce a
mg/L
for at least
minutes at design flow rates.
9.4
Elemental chlorine is
in color and is
times heavier than air.
9.5
Why must you take safety precautions when working with
chlorine?
9.6
What problems are created when chlorine is used for
disinfection?
