Wastewater Department

 

 

Treatment Facility

The Wastewater Treatment Process for Shipshewana

1. Lab – This is where most of the influent and effluent testing is done.
2. Headworks- This is where the influent enters the treatment process.  Larger non- biodegradable items such as rags and wipes are removed via a Huber fine screen.   The influent is also measured with a Parshall flume in the headworks building.
3. Raw lift station pump pit – After influent leaves headworks it enters the raw lift station pit.  This is where it is sent to the influent splitter box. 
4. Influent splitter box – This is where the influent is sent to one of two oxidation ditches, or if the flow is faster than desired it can be sent to the equalization basin.
5. Equalization Basin – This is where the influent is stored and aerated until it can reenter the raw lift station pump pit and be returned to the influent splitter box.
6. Oxidation ditch – This is where the influent is mixed with large amounts of bacteria, fungus, and protozoa that feed on the raw waste in the influent.  Most of the wastewater treatment process happens in the oxidation ditch.
7. Secondary Clarifier – The effluent from the oxidation ditch enters the secondary clarifiers.  This is where settling occurs.  The biomass that is mostly composed of large amounts of bacteria and stabilized pollutants settle to the bottom of the clarifiers where it is pumped into the RAS pit.  The clear effluent at the top flows into a weir and is sent to the tertiary clarifier.  Shipshewana wastewater treatment plant has two secondary clarifiers one has a volume of 151,800 gallons and the other has a volume of 310,340 gallons.
8. RAS (returned activated sludge) pits – This is a deep pit that is filled with the settled biomass from the secondary clarifier.  Once the pit is filled to a certain point pumps are activated to send the sludge to one of two places A) back to the oxidation ditch or B) to the digesters.
9. Tertiary clarifier – The clear effluent from both secondary clarifiers enters the tertiary clarifier where further settling occurs.  The cleaner effluent spills over the weir at the top of the clarifier and is sent to be aerated and disinfected with U.V. lights.  Sludge that still present settles to the bottom of the tertiary clarifier and is sent back RAS pit.
10. U. V. (ultra violet) disinfection system – The effluent from the Tertiary clarifier is sent to the U.V. channel.  There are two banks of U.V. lights rated to treat up to 500,000 gallons per day.  The effluent is once again metered here in a Parshall flume.
11. Discharge pipe – This is where to effluent is discharged into a ditch that leads to Page ditch.  All the final testing samples are taken from the discharge pipe.
12. Digester – This is where the activated sludge is sent from the RAS pit if it is not sent back to the oxidation ditch.  This process is called wasting and is a necessary part of keeping an activated sludge plant healthy.  Once in the digester the sludge is allowed to settle and concentrate.  As the slugged settles to the bottom of the digester the clear effluent drained off the top and sent back to the influent splitter box.  This process is called decanting.  Once the digester is so concentrated it stops decanting.  From here to concentrated sludge is sent to the drying beds.
13.  Drying beds – The concentrated sludge from the digester settles into the drying beds that are made of coarse sand and pea gravel.  Any liquid that is still in the sludge is either evaporated or makes its way thru the sand and gravel and is once again pumped back to the influent splitter box.
14. Dumpsters – Once the sludge is dried it is shoveled into the dumpsters where it is taken to Elkhart County land fill.