TM 5-814-8
(5) Toxicity. Toxicity is most often related to
ganic chemicals such as phenols and mercaptans,
aquatic organisms such as fish, arthropods, shell-
chlorine and its substituted compounds, and
fish, and microorganisms. The toxicity bioassay
many other chemical materials.
test has been developed to evaluate the relative
(3) Color. Color in water and wastewaters
toxicities of individual wastewaters. The purpose
may result from the presence of metallic ions
of the test is to determine the lethal concentra-
tion of pollutant that will kill 50 percent of the
from humus and peat materials such as tannin
test organisms (LC50) in a given period of time.
and algae. Color caused by suspended matter is
The LC50 is an indirect method of measuring
said to be "apparent color". Color caused by
toxicity.
colloidal or soluble materials is said to be "true
(6) Pathogens. Wastewaters that contain
color". True color is the parameter by which color
pathogenic bacteria can originate from domestic
is evaluated. An arbitrary standard is employed
wastes, hospitals, livestock production, slaughter-
to evaluate color. The color produced by 1 mg/L
houses, tanneries, pharmaceutical manufacturers,
of cobalt-platinum reagent is taken as one color
and food processing industries. The major patho-
unit. Dilutions of cobalt-platinum reagent are
gens of concern include certain bacteria, viruses,
made in the O to 70 unit range and placed in
and parasites.
special comparison tubes. Water samples are then
(a) The coliform group of bacteria has been
compared and matched between the cobalt-
used to indicate the bacterial pollution of water
platinum standard dilutions.
and wastewater. Generally used test parameters
(4) Radioactivity. Regulatory agencies have
employed as water quality indicators are total
established standards for the maximum allowable
coliform and fecal coliform. The total coliform
concentrations of radioactive materials in surface
test includes organisms other than those found in
waters. It is possible to differentiate between the
the gastrointestinal tracts of mammals.
following three types of radioactivity:
--alpha rays.
(b) The fecal coliforms are differentiated
from the total coliforms by incubation at an
--beta rays.
elevated temperature in a different, growth-
--gamma rays.
specific medium.
(a) Alpha rays consist of a stream of parti-
(c) Fecal Streptococci are non-coliform bac-
cles of matter (doubly charged ions of helium with
teria which are widely used as indicators of
a mass of four) projected at high speed from
pollution. Streptococci are particularly useful in
radioactive matter. Once emitted in air at room
that they are commonly found in heavily polluted
temperature, alpha particles do not travel much
streams and almost always absent from non-
more than 4 inches. These particles are stopped
polluted waters. Other pathogenic bacteria of
by an ordinary sheet of paper.
concern and related diseases are listed in table
(b) Beta rays consists of a stream of elec-
3-1.
trons moving at speeds ranging from 30 to 90
percent of the speed of light, their power of
Table 3-1. Common enteric pathogenic bacteria
penetration varying with their speed. These parti-
and related disease
cles normally travel several hundred feet in air
Disease
Bacteria
and may be stopped with aluminum sheeting a
Typhoid fever
Salmonella typhosa
tenth of an inch thick.
Paratyphoid fever
Salmonella paratyphi
Salmonellosis
Salmonella typhimurium
(c) Gamma rays are true electromagnetic
Shigellosis
Shigella sonnie, S. flexneri
radiation which travel with the speed of light, and
Vibrio chlorea
Cholera
are similar to x-rays but have shorter wave
Enteric infection
Pseudomonas aeruginosa
lengths and greater penetrating power. Proper
Enteric infection
Klebsiella sp.
Infectious pneumonia
Diplococcus pneumonia
shielding from gamma rays requires an inch or
Botulism -
Clostridium botulinum
more of lead or several feet of concrete. The unit
Brucellosis
Brucella sp.
of gamma radiation is the photon.
(d) Viruses are submicroscopic obligate par-
(d) Radioactive materials commonly used in
asites which can only replicate in a host cell.
tracer studies in research in biology, chemistry,
However, viruses can survive for weeks, even
months outside a host cell awaiting the opportu-
iodine (125). In sewers and waste treatment plants
c e r t a i n isotopes, s u c h as radioiodine and
nity to reinfect another host. Viruses cause a
large number of diseases including the common
radiophosphorus, accumulate in biological slimes
cold, measles, poliomyelitis, mumps, hepatitis,
and sludges.
3-5
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