Overview of a Wastewater Treatment Facility

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Overview of a Wastewater Treatment Facility
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THE PROCESS1. Water from Lake Michigan enters
the intake crib at depths of 20 to 30 feet.2.
Water enters the purification plant's intake
basin through a tunnel beneath the lake bed.3.
Water is filtered through eight traveling screens
to catch debris.4 Water is pumped by low lift
pumps up to 25 feet for the first chemical
treatment.5. Water flows from the chemical
application channels.6. Water flows through
mixing basins to begin the flocculation
process.7. Flocculated water passes into
settling basins to sit for hours allowing floc to
settle.8. Water is filtered through precisely
graded sand and gravel performing a "natural
polishing".9. Filtered water flows into
clearwells for its final chemical
application.10. From finished water reservoirs
water flows to the distribution system.
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We use several chemicals in the purification and
treatment of water-Chlorine to disinfect the
water. -Aluminum Sulfate or Alum and Polymer
for coagulation to settle out impurities. -Blende
d Polyphosphate to coat pipes and prevent lead
leaching. -Activated Carbon to remove
unpleasant tastes and odors. -Fluoride to help
fight cavities in children's teeth.Chemical
amounts are quite small. The total volume needed
to treat 100 gallons of water is about a teaspoon
full. That's 15 parts of chemical to 1 million
parts of water.
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Primary Treatment Primary treatment consists of
removing contaminants by some physical
mechanism Screens remove debris which can clog
the machinery. The wastewater flows into
chambers where heavy solids such as sand and grit
sink to the bottom these solids are washed
before being deposited in a sanitary
landfill. It then goes to a primary settling
tank where a significant portion of the organic
solids settle to the bottom while fats, oils and
grease rise to the top. Revolving "arms"
simultaneously scrape the primary (untreated)
solids from the bottom and skim the grease from
the top.
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Secondary Treatment Secondary treatment usually
employs a biological process whereby a large
population of micro-organisms help convert the
remaining organic material into other forms which
can be easily separated into solids and a clear
liquid. The primary affluent flows through a
series of large rectangular aeration tanks which
have been seeded with bacteria and other microbes
(tiny organisms which exist naturally in plant
and animal life). Filtered air is pumped through
the liquid to enable the microbes to breathe and
grow. In the constantly churning water, these
microbes flourish and multiply, eating the
remaining organic materials and nutrients in the
wastewater. This mixture of microbes and water
flows into a secondary settling tank. The
microbes, now stabilized, clump together and
settle to the bottom of the tank where they
become part of the organic residuals and are
removed. Approximately eighty-five percent of
these microbes are recycled to the start of the
aeration tanks to begin the biological treatment
process for the primary effluent. The cleaned
water flows out of the top of the secondary
settling tank to be returned to the waterway or
to the tertiary treatment process.
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Tertiary Treatment Tertiary treatment is only
required when the final effluent must be so clean
that 95 or more of the contaminants must be
removed by wastewater treatment. Tertiary
treatment may include Filtration Removal of
Ammonia and other specific contaminants Disinfect
ion to destroy bacteria which can cause disease
in humans.
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Future Research
Treatment process for BP Some commonly used units