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A sanitation plant is a facility which treats wastewater. As water passes through the plant, it undergoes a number of processes which are designed to remove dangerous impurities, yielding water which is safe and stable at the other end of the sanitation process. Sanitation plants vary widely in size and scope, and can be found all over the world, primarily in urban areas and manufacturing centers. They are usually closed to the public, although those who are curious may be able to arrange a guided tour of the facility.
One obvious use for a sanitation plant is in the treatment of water which has become contaminated by human waste. Many disposal systems for human waste rely on transporting the waste in water, with the water being treated at a sanitation plant or in a septic tank. In these facilities, water can be treated to varying levels of purity and then released. Some sanitation plants sell their water for agricultural use, while others may distribute their water to city landscaping sites for the purpose of keeping a city green without using fresh potable water on landscaping. Others release treated wastewater directly into waterways such as rivers and streams.
A sanitation plant can also handle water which has become contaminated by other materials, such as chemicals. Some factories have attached sanitation plants which process water which has been compromised through use in the factory. These facilities may be required to treat their wastewater before releasing it into a sewer system, with the goal of removing impurities which a conventional sanitation plant cannot handle. Sanitation plants can also process greywater, in regions where sewage and greywater are handled separately.
A variety of processes and techniques can be used at a sanitation plant, depending on the type of material being handled. Basic filtration is used, along with techniques such as allowing contaminants to settle to the bottom of large holding tanks while relatively clean water is allowed to flow out of the top of the tank. Plants can also address specific issues such as known bacteria in the water or specific chemicals which may not be eliminated through regular wastewater treatment practices.
Sanitation plants may be run as a service to the public by a local government which wants to ensure that sanitation is provided for environmental health reasons, although they can also be run as a for-profit endeavor. Specialty sanitation plants such as those which attach to hospitals and manufacturing facilities are designed by sanitation engineers who address the specific needs of the system in their designs.
@Mor - I'm not sure if any cities bother to put in a sanitation plant to deal with storm water. They should, maybe, but unfortunately it's the kind of thing that only affects them peripherally, so they usually don't bother.
Sanitation plants are generally only used to deal with sewerage which simply cannot be ignored in a large city, or with processing chemicals from factories.
I personally think that in a few years, when clean, potable water becomes less available since we are using it up at a rapid rate, people will install more sanitation plants simply because they will want to be able to use storm water as drinking water.
And it wouldn't be a bad thing either. I actually think it's a shame at the moment that more households don't make use of rainfall, rather than relying entirely on city water lines.
@indigomoth - Well, it would be cleaned by going through the plants. There are a few cities that are doing this with their storm-water which can be a bit like waste-water.
They plant a section of the city, near the river or the harbor, with a bunch of swamp plants, hopefully in a way that looks good as well and provides a bit of green for the city.
Then they divert the storm water drains to that section.
It's much cheaper in the long run than trying to run a sanitation plant, since the water generally isn't that bad, but it shouldn't be dumped straight into the ocean either. As long as they have points that collect the larger, non-organic debris they are all right.
One of the highlights of the ecology course I did at university was a visit to a sanitation plant.
I know that sounds a bit silly, because it doesn't sound like something that you'd really want to do, but aside from the smell it was really very interesting.
The one we visited was well set up for visitors though, and had scale models of all the equipment and the plant itself. The man taking us around also told us all kinds of interesting facts.
For example, this sanitation plant poured its treated water straight into the river, which upset local people since they assumed it was still somewhat contaminated. It also upset the local tribe because they believed it was taboo to put anything that had been near sewerage back into the river even if it was superficially clean.
The water they put back in, however, was 100 times cleaner than the water that was already in the river.
The way they fixed it was to plant a whole bunch of swamp plants where the water was added to the river, so that the local people were satisfied that it was "cleaned" through the plants.