Q&Amy: Getting water from dirty to clean

[tflaris]

See link for photos:
http://www.greenvilleonline.com/stor...lean/20863203/

1. REMOVAL OF LARGE SOLIDS

As water comes into the treatment facility, it goes through a bar screen that catches debris that has either been flushed in people's homes or washed into the sewer system through manholes. That can include sticks, diapers and condoms.

The water then heads to a vortex grate removal system in which more grit and sediment are removed through a spinning process.

Human waste is dissolved in the water by the time it reaches the treatment facility.

2. CLARIFIER

Water then flows into a large clarifier, a 20-feet-deep tank that holds 30 million gallons of water.

As velocity slows and the water sits in this tank, solids settle to the bottom and greases float to the top and are skimmed off.

"You're left with a clean layer of water in the middle," said ReWa public relations coordinator Ashley Rhinehart.

3. BASINS OF "BUGS"

The water is then piped to two basins where microorganisms, basically good bacteria, are added by the tons to consume the nitrogen, phosphorus and ammonia in the water.

One side of the basin is aerated for bacteria that thrive in aerobic ("with oxygen") environments; the other is not for those that prefer anaerobic ("without oxygen") environments. Both sides are kept moving so that the bacteria do not settle to the bottom.

4. MICROORGANISMS AT WORK

The water is so full of the microorganisms at this stage that it looks brown, though it's just billions and billions of bacteria munching away on the nutrients in the water.

5. CLARIFYING AGAIN

The water flows next to a secondary clarifier where it once again sits to allow the bacteria to settle out.

The resultant "sludge" is tested for bacterial viability. If they're doing well, they're returned to the basins to keep at it. If they're at the end of their life cycle, they're processed through another level of treatment to become nutrient-rich biosolids that are used as an agricultural fertilizer.


6. DEEP BED SAND FILTERS

The now-clear water is then trickled through deep-bed sand filters, which remove any remaining suspended solids.

7. DISINFECTION

The final step is to treat for fecal bacteria. The water is flowed over a long series of underground UV lights, which alter the DNA of the bacteria and prevent them reproducing. Once they die off, the bacteria is completely eliminated.

This disinfection process used to involve chlorine, but ReWa no longer uses the chemical in water treatment, Rhinehart said.

Once the water is disinfected, it is returned to either the Reedy, Enoree or Saluda river.

http://www.greenvilleonline.com/stor...lean/20863203/


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[Jack Hammer]

Interesting, I would have thought the process to be both more involved and use multiple chemicals. Glad to read its more "organic" in nature

[MORGAN]

Yes - years ago I went on a tour of a sewage treatment plant and found it very interesting that the process was almost entirely mechanical and biological - little or no chemicals involved.

[tflaris]

Downside of this process is it does not remove any pesticides, oils, chemicals and it also does not remove any of the pharmaceuticals that pass through our body in our urine

TF


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