TM 5-814-8
d. Wastewater solids. Wastewater solids are
based chemical manufacturing, machining, vehicle
maintenance, kitchen and restaurant wastes and,
present in nearly all wastewater discharges. Sol-
ids occur in wastewater as a result of stormwater
to a lesser degree, domestic wastewater. Oil and
runoff, sanitary discharge, chemical precipitation
grease is an indirect measurement defined and
reactions in the waste and direct discharge of
quantified by an analytical procedure. Oil and
solid materials.
grease is an expression of all substances ex-
(1) Definitions. Waste solids are classified
tracted by the organic solvent (Freon) employed
according to gross physical properties and chemi-
in the test procedure. Oil and grease may include
hydrocarbons, fatty acids, soaps, fats, waxes, oils
cal composition. The three basic types of solids
include:
and any other Freon extractable substance that
--settleable solids,
will not volatilize during the test procedure. Oil
and grease, in large quantities, is a dangerous
--suspended solids (TSS), and
--dissolved solids (TDS).
environmental pollutant. Oil and grease is diffi-
Settleable solids are particles which settle out of
cult to remove by conventional treatment pro-
a wastewater sample during a 1 hour settling test
cesses such as anaerobic or aerobic biological
processes and is an interference in most physical-
using an Imhoff cone. Grit and most chemical
sludges are settleable solids. They are denser
chemical treatment processes. Oil and grease
treatment usually consists of removal by skim-
than water and, therefore, cannot remain in
suspension. Suspended solids are particles re-
ming or flotation and disposal by reuse, incinera-
tained by filtering a wastewater sample. The
tion, or landfilling.
(2) Phenol. Phenol is encountered most fre-
suspended solids test may include settleable sol-
ids if the sample is thoroughly mixed. Dissolved
quently in the petroleum refining and chemical
processing industries, but is present where indus-
solids are basically salts of organic and inorganic
molecules and ions that exist in solution.
trial activities utilize petroleum distillates. Phenol
(2) Testing. Wastewater solids may be classi-
is very soluble in water, oils, carbon disulfide and
numerous organic solvents. The wet chemical
fied by direct gravimetric test methods. Sus-
analysis of phenol measures directly a variety of
pended and dissolved solids are termed "volatile"
phenolic compounds. P h e n o l is a toxic and
if they are vaporized after ignition for 1 hour at
1,022 122 degrees F in a furnace. In
mutagenic substance in high concentrations and
wastewater treatment, solids are said to be non-
may be absorbed through the skin. Phenols are,
for the most part, biodegradable.
filterable or insoluble if they are retained on the
surface of a 0.45 micron filter. The filtrate is said
(3) Cyanide. Cyanide is found in metal plat-
ing, petroleum refining, plastics, and chemicals
to represent the soluble fraction of the liquid.
manufacturing wastewaters. The cyanide ion is
e. Significant inorganic parameters. There are
many inorganic parameters which are important
highly toxic to aquatic life and humans at very
low concentrations. Most cyanide appears as a
when assaying potential toxicity, general charac-
terization, or process evaluation. Although special
chemical complex with a metallic compound. As a
situations require the evaluation of any number
result, toxicity of cyanide depends upon the
nature of the complex. Some cyanide compounds
of inorganic analyses, it is the intent here to
discuss only the more prevalent ones.
are harmless. Cyanide compounds are usually
(1) Acidity. The acidity of a wastewater is
biodegradable and are otherwise treatable by
important because a neutral or near neutral wa-
alternate methods.
(4) Surfactants. Surfactants are found in
ter is required before biological treatment can be
household and industrial cleaning detergents and
effective. In addition, regulatory authorities have
many industrial wastewaters. The presence of
criteria which establish strict pH limits to final
surfactants is indicated when there are large
discharges. Acidity is attributable to the non-
ionized portions of weakly ionizing acids, hydro-
quantities of foam in the collection or treatment
system.
lyzing salts, and certain free mineral ions. Micro-
(5) Other organic compounds of significance.
b i a l systems may reduce acidity in some
Many wastewaters contain U.S. EPA identified
instances through biological degradation of or-
toxic organic compounds not identifiable except
ganic acids, or they may increase acidity through
by direct measurement using specialized analyti-
vitrification or other biochemical processes. Acid-
ity is expressed as mg/L CaC03.
cal techniques such as infrared spectrophotome-
try, gas chromatography, gel chromatography
(2) Alkalinity. Alkalinity may be considered
and mass spectrometry. Other analytical methods
the opposite of acidity and it is also expressed as
may be required depending upon the substance.
mg/L CaC03. Alkalinity is imparted by carbonate,
3-2
Previous Page
