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Re[4]: [at-l] National Parks and Snowmobiles
"Well as an Environmental Engineering major I have to point out that normal
secondary treatment gets more like 99% and if you have a tertiary treatment
plant its more like 99.9%.
I forget what the law calls for and I haven't paid attention to the details in
recent years, but primary treatment has to remove 60% or so of the wastes from
the water; secondary around 90% -- maybe 95%. We never had a tertiary plant in
Maine, but somehow, I doubt if it removes 99.9 percent on a consistent basis.
There is not a secondary waste water treatment plant in Maine -- and I strongly
suspect the nation -- that consistently removes 99 percent of the wastes from
the environment. In fact by any definition that makes sense none of them remove
anything from the "environment." The process introduces bugs that eat and thus
eliminate (kill) some harmful organisms for sure. Some damaging chemicals and
fertilizers are kept from the water bodies and transferred to the land.
For almost all treatment plants the process is basically biological. Wastes are
collected in a giant tank or basin. Oxygen and food (poop) are introduced. Bugs
naturally found in the environment use the oxygen and poop to stay alive and
reproduce long enuf to eat and digest much of the wastes. Some harmful bugs are
eliminated by the eating. Others are introduced by the process.
Regardless everything stays in the environment. Some pollutants escape to the
atmosphere. Some get dumped into rivers and streams or the ocean. Most -- the
bodies of pollution-eating bugs, their excrement and the stuff they either
didn't eat or couldn't eat, or couldn't digest gets either burned or buried --
or in New York's case until a few years ago at least -- just carted out to sea
and dumped.
New York had a most fascinating system. At enormous expense they collected all
the sewage, separated it into polluted water and solids -- and then dumped it
all in the ocean.
Weary