Septic tanks and grease separators
In a septic tank, solids either sediment or dissolve into the waste water. This step avoids silting in the sewers and reduces the risk of flooding and odour nuisance. Substances discharged into a septic tank are converted into small particles.
Grease separators work by the principle of gravity. With their higher density than water and vegetable or animal fats, the heavy components sediment in the sludge collecting chamber at the bottom of the separator.
How does a septic tank treat waste water?
Three processes take place in a septic tank:
- the heavy particles sediment,
- organic material is broken down by the anaerobic biological process,
- foam and floating components rise to the surface and form a crust.
A well-designed and managed septic tank reduces the burden on the subsequent biological treatment and ensures that only the liquid fraction flows through. In this way, no blockages occur in the downstream process. Septic tanks are successfully used at most waste water treatment plants of filling stations or for treating sanitary waste water.
How do grease separators work?
The light components, such as fats and oils, float up to the water surface (separation space). Once the grease and sludge have been removed, the waste water is led off to the sewer system, with or without the use of a feed pump.
The catering and food industries in particular use grease separators to retain fats and oils that disrupt the proper functioning of a biological treatment plant.