Bacterial Survival in Snow
Made from Wastewater
LOUISE V. PARKER, MELINDA L. YUSHAK, C. JAMES MARTEL,
AND CHARLES M. REYNOLDS
INTRODUCTION
Wastewater is the used water supply of a commu-
lation, sedimentation followed by filtration and acti-
nity, and thus is a dilute solution of fecal matter and
vated carbon, reverse osmosis, and ion exchange.
wastes. One of the primary purposes of wastewater treat-
Delta Engineering (Ottawa, Canada) has developed
ment is to remove constituents that can reduce the qual-
a patented process, called Snowfluent, that uses sec-
ity of receiving waters. This treatment includes remov-
ondary wastewater as a water source for snowmaking.
ing any substances that would increase color, odor, or
During the winter, the wastewater is stored as snow. In
clarity, or decrease dissolved oxygen (DO) levels. This
the spring, the meltwater discharges first to the unfro-
includes removing any nutrients that can cause growth
zen ground until it becomes saturated. The remaining
of algae and removing any health hazards, such as
meltwater is run off and discharges to surface waters.
pathogenic microorganisms or toxic contaminants.
The reported benefits of this treatment process include
Typically, the pathogenic microorganisms that are found
a high level of treatment; ability to function in the cold,
in wastewater cause gastrointestinal illnesses charac-
where other processes either fail or are less effective;
terized by diarrhea and abdominal cramps, which may
elimination of the need for new treatment lagoons for
be accompanied by vomiting and fever. Microorgan-
wastewater storage in cold weather; elimination of the
isms known to cause illness include bacteria, viruses,
need for chemical flocculation of phosphorus; elimi-
protozoan cysts, and the eggs (ova) of helminths (para-
nation of bacteria without requiring disinfectants; a low
sitic worms). Bacteria of concern include some species
operating cost; and possible use for revenue-generat-
of Shigella, Salmonella, Leptospira, and Vibrio, and
ing agricultural purposes.
strains of Escherichia coli (E. coli). Viruses of concern
According to the manufacturer, most of the contami-
include enteroviruses (including polio, Coxsackie, and
nants are deposited with snow except for gases such as
infectious hepatitis [type A] viruses), reoviruses,
ammonia and carbon dioxide, which are reduced dur-
adenoviruses, rotaviruses, and Norwalk-type viruses.
ing snowmaking. The initial meltwater, which contains
Pathogenic protozoa include Giardia lamblia,
most of the contaminants, then percolates into the soil
Cryptosporidium, Balantidum coli, and Entomoeba
surface where the contaminants are adsorbed. These
histolytica. Helminths of concern include Ascaris
adsorbed nutrients are removed in the warmer months
lumbricoides (roundworm), Enterobius vermicularis
by plant uptake and bacterial degradation. Later melt-
(pinworm), and Trichuris trichiura (whipworm).
water is reported to be relatively uncontaminated and
Primary wastewater treatment removes floating and
can be allowed to discharge into surface water.
settleable solids by using physical operations such as
The process by which impurities are concentrated
screening and sedimentation. Secondary treatment re-
in a snowpack has been explained by Colbeck (1981)
moves most organic matter and suspended solids by
as follows: exclusion of impurities occurs after snow
using biological and chemical processes such as acti-
deposition during the process of grain coarsening and
vated sludge, fixed film reactors, lagoons, and sedimen-
freezethaw cycles that the snowpack undergoes. This
tation. Tertiary treatment removes other remaining con-
concentrates a major fraction of the impurities present
stituents, including nitrogen (N) and phosphorus (P),
in the snowpack onto the outer surface of snow crys-
through treatment processes such as chemical floccu-
tals and into interstitial water. From there the impuri-
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