LVM's Environmental Action Blog

The purpose of this blog is to convey the importance that life choices and daily decisions have on the environment. I will, as a member of the kayaking community, effectively convey the importance and immediacy of environmental issues written in the paddling vernacular.

Saturday, February 05, 2005

sewage education

Have you ever wondered where the holes at the bottom of your drains and toilets lead to? Well, whether you have or not, here’s a tour of the fabulous world of sewage treatment.

Hendersonville, North Carolina’s wastewater treatment plant has been in operation for three years. With a capacity of six million gallons per day, this advanced facility produces some of the cleanest effluent in the country: cleaner than the creek it releases into (BOD wise). The only time the average household user puts unneeded stress on them and the creeks they release into is by pouring cleaners and other harsh chemicals down the drain.


First the solids are removed. The plant workers find all sorts of interesting stuff in here from live snakes to plastic baggies containing mysterious powders and pills and even $100 bills. fyi: if you lose anything down the drain, don’t call up and expect anyone at the plant to fish it out for you.

The solids removed at this step are dumpstered off to the landfill.

Next the sewage is moved into two huge tanks were oxygen is bubbled in from the bottom in what is called “activated sludge” treatment.
Here’s Scott, our guide, in front of the activated sludge tanks:

This step in the process actually cleans the water the most, with NO chemicals. The micro organisms and macro invertebrates, which are already present, feed off the organic matter dissolved in the water. The oxygen bubbled in from the bottom allows them to grow and feed at maximum speed, cleaning up the water at an amazing rate. These tiny organisms are the workhorses of wastewater treatment.
Here’s an example of one of the little jammers:

Image Source

The plant uses giant electric powered motors to pump the air into the tanks.

Some plants like MSD in Asheville, North Carolina have built their own hydroelectric dams to supply the massive amount of electricity needed to power these bad boys.

Next the water visits a sand filter for further solids removal.

This one is empty at the moment; so you can get a good look at the filtering mechanisms.

The water then passes through a clarifier. The clean water rolls slowly off the top out of this tank near the end of the treatment process. Notice the change in clarity of this water compared to that of the activated sludge tanks.

From here the water will pass through a final treatment with UV lights. Some plants use chlorine gas for this step to treat the water.
Next stop the river.
Solids removed from the activated sludge, clarifier, and sand filter steps are sent to a thickner, like the one pictured below, and other water removal processes before being transported to the landfill or turned into very potent fertilizer.

You can actually pick up this fertilizer for your own personal usage, and it’s free! Just contact your local waste water treatment plant and ask; they’d be fired-up about you coming to take some away.
Yellow Pages is a great place to look for the plant near you.

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