TM 5-814-8
battery manufacture, sodium hydrosulfite manu-
all forms of life in the proper concentrations but
facture and other chemical production. Zinc is a
does not persist in aquatic systems. These two
nutritional trace element but is toxic at higher
qualities have helped promote the use of chlorine
concentrations.
as a disinfectant. However, chlorine does react
(e) Lead. Lead is present in wastewaters
with other chemical compounds such as ammonia
from storage battery manufacture, drainage from
and certain hydrocarbons to form the toxic
lead ore mines, paint manufacture, munitions
chloramines and potentially toxic or mutagenic
manufacture, and petroleum refining. Lead is
chlorinated hydrocarbons. For this reason, chlori-
toxic in high concentrations.
nation is not recommended for certain industrial
and combined domestic/industrial waste streams.
(f) Nickel. Nickel is present in wastewaters
from metal processing, steel foundry, motor vehi-
(8) Chlorides occur in all natural water sys-
tems and many industrial waste streams. Sea-
cle and aircraft, printing and chemical industries.
Nickel may cause dermatitis upon exposure to the
waters are very high in chlorides. Chlorides are
skin, and gasrointestinal distress upon ingestion.
relatively harmless to humans in low concentra-
tions. At a concentration of 250 mg/L, drinking
(g) Mercury. Mercury is used in the electri-
cal and electronics industries, photographic chem-
water is found to have an objectionable taste. In
icals, and the pesticides and preservatives indus-
some cases, water containing concentrations of
tries. Power generation is a large source of
chloride up to 1,000 mg/L are consumed without
mercury release into the environment through the
ill effects. Chloride concentrations of 8,000 to
combustion of fossil fuel. Mercury in its methyl-
15,000 mg/L have been reported to affect ad-
ated form is a highly toxic compound. In its
versely biological waste treatment systems.
elemental form, it is readily absorbed by inhala-
(9) Heavy metals. Some of the heavy metals
tion, skin contact and ingestion.
of interest are copper (Cu), chromium (Cr), cad-
f. Additional wastewater characteristics.
mium (Cd), zinc (Zn), lead (Pb), nickel (Ni), and
(1) Temperature. Temperature is a very im-
mercury (Hg). These materials may be measured
directly. These elements may be inhibitive or
portant wastewater characteristic. The chemical
toxic to aquatic and terrestrial organisms and the
equilibrium of complex wastewaters is very tem-
microorganisms employed in biological waste
perature dependent. Different reactions may be
found at higher temperatures as compared to
treatment systems.
lower temperatures. Waste treatment system effi-
(a) Copper. The primary sources of copper
in industrial wastewaters are metal process pick-
ciency is affected by extremes in temperature. At
low temperatures (39 degrees F), biochemical and
ling baths and plating baths. Copper may also be
chemical reaction rates are extremely slow, and
present in wastewaters from a variety of chemical
waste treatment operations are often severely
manufacturing processes employing copper salts
limited. At temperatures greater than 100 degrees
or a copper catalyst. Copper is an essential
F, many waste treatment plants experience oper-
nutrient for most organisms including humans.
ating difficult y. Biological processes are impaired,
Copper can impart a bitter taste to water in
air and oxygen volubility becomes limited, and
concentrations above 1 mg/L. Copper salts are
used to control algae growth in reservoirs and
other physical properties such as sludge density
and settling rate affect overall waste treatment.
farm ponds.
(2) Tastes and odors. Tastes and odors in
plating and anodizing wastes, tannery wastes,
water are generally associated with dissolved
inorganic salts of iron, zinc, manganese, copper,
and in certain textile processing wastewaters.
sodium, and potassium. Phenolics are a special
Chromium commonly appears in the hexavalent
nuisance in drinking water supplies especially
(+6) and the trivalent (+3) valence states and
after chlorination because of their very low taste
also exists in less soluble complexes. Hexavalent
and odor threshold concentration (less than 0.2
chromium is highly toxic to microorganisms.
(c) Cadmium. C a d m i u m is present in
parts per billion). Petrochemical discharges and
liquid wastes from the paper and synthetic rubber
wastewaters from metallurgical alloying, ceram-
industries often cause taste and odor problems.
ics, electroplating, photography, pigment works,
textile printing, chemical industries and lead mine
Sulfides from these sources cause odors in concen-
drainage. Cadmium is relatively abundant in the
trations of less than a few hundredths of a part
per million. Tastes and odors may also be associ-
earth's crust and the metal and its salts are
highly toxic.
ated with decaying organic matter, living algae
(d) Zinc. Zinc is present in wastewater
a n d other microorganisms containing essential --
streams from steel works, rayon manufacture,
oils and other odorous compounds, specific or-
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