SOIL, SEDIMENT AND SLUDGE: EX-SITU CHEMICAL/PHYSICAL TREATMENT
Typical Gravity Separation
Typical Gravity Separation System
Gravity separation Process:
Note:
Uses:
Limitations:
- A solid/liquid separation process, which relies on a density difference between the phases to separate the contaminants from their medium. This results in a much smaller volume of concentrated wastes requiring further treatment..
- Once the contaminated concentrates have been separated, the relatively uncontaminated fractions left can be regarded as treated soil and replaced in the ground.
- It is often used to separate particles of different sizes, but can also be used to remove immiscible oil phases.
Note:
- It is often preceded by coagulation and flocculation to increase the particle size of the finer particles, thereby also allowing their removal.
- Other separation techniques include Magnetic Separation and Sieving/Physical Separation.
Uses:
- The target contaminants: SVOCs, fuels & inorganics (including radionuclides)
- Can also be used on selected VOCs and pesticides.
Limitations:
- High clay and moisture content will increase treatment cost.
- May get odour problems when treating organic sludge.
- Highly variable cost - not able to give approximate.
- Equipment size and effectiveness of gravity separation depends on the solids settling velocity (a function of the particles size, density difference, fluid viscosity, and particle concentration).