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Small Wastewater Treatment

Small scale wastewater treatment

The process of sewers water  system in university or hospitals like public organization having small scale waste water treatment inside the campus to control their sewage water.

Complete mixing aeration without primary sedimentation is exercised in cases of small wastewater flows as at villages and towns. The size of the aeration basins ranges from metal tanks with diffused aeration to accommodate the waste flow from few hundred persons to mechanically aerated concrete basins such as an oxidation ditch.


Primary waste water treatment involves the following steps.

  1. Screening
  2. Pumping
  3. Grit removal

The first step to screen solids by screens which are bars of openings of about 25mm.

The collected solids are removed from bars by traveling rakes that lifts them to the top of the unit

Here the screenings may be fed to a shredder and returned to the waste water flow.

A shredder or communitor cuts solids .

A communitor is not often used with  mechanically cleaned bar screen .

Two common types of shredding devices

  1. The comminutor consists of a vertical revolving slotted drum screen submerged in a flow channel such that the waste water passes into the drum through slot sand is discharged from the bottom of the unit. Solids too large to enter the slots are cut into small pieces enough to pass through while stringy material that enters partway is cut by shear bar. The BARMINUTOR, combination of screening and comminuting machine, has high speed rotating cutter that travels up and down on the front of the bar screen.
  2. Accumulated solids are shredded and flushed through with waste water. Cutter action can be automatically initiated when solids have accumulated on the screen face and can be stopped when they are shredded and passed through.