Flush.
Swirl. Swoosh – bye. Ever wonder where that goldfish ended up
when you were 12 years old? Indoor plumbing is something that we
have all gotten used to – the day of the outhouse is over … for
the moment. The sewer systems use water as the great sweeper – the
idea that the solution to pollution is dilution really caught on
during the post WWII era. We flush and run and rarely give thanks
for the notion of a hot shower in the morning.
The municipal waste treatment plants dot the rivers in
place just before every hamlet. The residents count on this
cleansing process to bring them cool, clear water – bacteria and
odor free. The chemical treatments of the water remain out of sight
and out of mind – until the process breaks down and we get yuck.
Lets cover some of the standard processes of waste-water treatment.
The first process is filtration. This is accomplished
by having screens on the collection port – which keeps the larger
stiff like branches, rocks and fish out of the water intake system.
A smaller set of screens may be behind the larger ones – screen
mesh size dictates how much small material can be removed. There is
always some material that gets through – the test for total
suspended solids tells us that amount. The test is rather simple –
pour a liter of water through a dry, carefully weighed filter paper,
in a Buchner funnel using a side-arm filter flask and a water
aspirator. The pressure pulls the water through the paper and the
solid materials are measured by weighing the filter paper again,
after it is dry.
Water is routinely tested for basic physical
parameters. The clarity of the liquid is measured as turbidity. A
small sample is placed in a cell in a light box with a carefully
measured path-length. The light is measured and compared to a path
that has a cell with cloudiness, but no water. The comparators are
made from a gel which has known n.t.u – nephalometric turbidity
units. The standards are purchased in sealed vials and run at the
same time as the samples.
The pH and Conductivity are also measured. The pH is a
measure of the acidity of water – placed on a logarithmic scale
with units between one and fourteen. Seven is considered neutral and
desirable, lower numbers imply that the water is acidic – higher
numbers correspond to basic. River and stream waters tend to average
about pH 7.3 – the actual pH is a function of the type of land that
the water runs through. Conductivity is a measure of the ionic
conductance through the solution – which increases as a function of
salt dissolved. The more conductivity, the more percentage of salt
in the water. The ocean is composed of salt water – natural water
runs the gamut of values, depending on the solubility of the salts of
the earth.
The conductivity can be related to the total dissolved
solids. To measure total dissolved solids requires taking a liter of
water to complete dryness and weighing the residues. The combination
of both the suspended solids and the dissolved solids together make
the total solids of the material. High turbidity increases TSS
without affecting TDS. Usually, salts dissolved in the water will
not have much effect.
However
– hard water is material that has a lot of dissolved calcium and
magnesium salts, which can cause problems with washers and water
heaters by causing scale. Scale happens when precipitates come out
of solution to take up solid capacity within the containers, plumbing
or pipes. Some people use water filters to remove this scale, the
medium being either activated carbon, sand or an ion-exchange resin.
These filters have a limited capacity based on their size and have to
be monitored for break-through, at which time a new filter can be
substituted for the old one.
Sometimes – municipal water systems will use
flocculation and sedimentation in large tanks to clean up the water.
This process involves mixing a chemical with the water that adsorbs
the other materials hat are caught in the solution. Lime is a
typical flocculant. The tank water is stirred with lime then allowed
to settle – the water is then decanted off the solid lime, which
has all the impurities adhered to the surface. The settling is
important – the flocculant would otherwise plug the flow pipes.
The size of the tanks are over thousands of gallons – there is an
economy of scale in treating large batches of water, when continuous
flow methods are not available.
The
temperature of the water is also a water quality parameter. Fish
tend to be very sensitive to temperature change. Hot water also
tends to dissolve more materials than colder water, but really –
the temperature of running water only varies when the inputs are
either direct sun/shade or a large industrial system. Many times –
the water released by factories is not controlled locally. The
waterways are used as waste carriers and the industries are
'permitted' to use the rivers as sewers because 'that is the way
things have always been done'. This is not cool, but try complaining
and you get to be a target. The Erie River near Pittsburgh once
caught fire from the additional waste additions. Don't get me
started on acid mine drainage.
Another
fairly important test is for fecal coliform. This is the live
bacterial material found in animal poop – as expressed in the form
of e-coli.
E-coli is the
biggest evil on the planet – killing unsuspecting patrons of
unsanitary restaurants. Only it is not – it is common stomach
bacteria that comes in many forms and rarely lives outside of
stomachs for very long. Finding e-coli in water systems is a big red
flag – but it is always found in natural water systems, where
animals haven't figured out indoor plumbing. One cow pattie is fine
for nailing a farmer whose fields have run off, yet the municipal
systems tend to put out poor quality water, while getting a pass.
The
EPA with its clean water act is more responsible for polluted waters
than anyone – it gives permission to pollute up to certain levels
to people that own the system – George Carlin style. Don't kid
yourself – the water game is a game of control just like the
back-story to the movie Chinatown
implies. If you own the water rights, you still have to service the
government that insists that you buy the water however they deliver
it. It comes with residual chlorine at the end of the tap. Thus, in
the Monsane whirled, the way to mitigate for coliform seems to be to
add a bigger toxin to kill the coliform – mask the problem and
poison you. It helps to aerate municipal tap-water for about an hour
before drinking – or boil the water to remove the volatile
impurities.
We
have not even begun the rant on fluoridation, but alas – our essay
space has expired for another day. Keep yourself hydrated with good
water.
Namaste' ... doc
PS - Doc cannot control when the paragraph is bold or not bold. There is no ulterior motive in the print style.
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