______ technique in waste management is mainly accomplished in situ and includes soil washing and the extraction of contaminant vapour from soil for highly volatile, water-insoluble contaminants such as gasoline?

Correct option is C

The correct technique for waste management involving soil washing and extraction of contaminant vapour for volatile, water-insoluble contaminants like gasoline is mobilization.
Mobilization refers to the process where contaminants in the soil are moved or extracted through physical, chemical, or biological processes. This technique is typically accomplished in situ, meaning it occurs at the contamination site itself, without excavation of the soil.
Key processes in mobilization include:
1. Soil Washing:
· Uses liquids (such as water, solvents, or surfactants) to flush out contaminants from soil particles.
2. Vapour Extraction:
· Also known as soil vapour extraction (SVE), this process extracts volatile organic compounds (VOCs) like gasoline vapours from the soil using vacuum systems.
In situ mobilization is especially effective for removing highly volatile and water-insoluble contaminants like petroleum hydrocarbons (e.g., gasoline, diesel).
Information Booster 1. Techniques of Mobilization:
· Soil Vapour Extraction (SVE): Used for volatile contaminants.
· Surfactant Enhanced Aquifer Remediation (SEAR): Uses surfactants to mobilize contaminants.
· Flushing: Uses chemical solutions to mobilize contaminants for extraction.
2. Advantages of Mobilization:
· Cost-effective since it doesn’t require soil excavation.
· Minimal disturbance to the site.
3. Applications:
· Commonly used for gasoline spills, chlorinated solvents, and volatile organic compounds (VOCs).
4. Limitations:
· Ineffective for non-volatile contaminants or contaminants bound tightly to soil particles.
5. Safety Considerations:
· Proper handling of extracted vapours to avoid air pollution.
Additional Knowledge · In situ containment (Option a):
· Involves isolating contaminants in place to prevent migration (e.g., using barriers).
· Not suitable for extracting volatile contaminants.
· Immobilization (Option b):
· Stabilizes contaminants by chemically binding them to soil particles, reducing mobility.
· Effective for heavy metals, not volatile contaminants.
· Vitrification (Option d):
· Involves heating soil to form a glass-like structure that immobilizes contaminants.
· More applicable for radioactive or heavy metal contamination.
Key Points:
· Mobilization is the best method for volatile, water-insoluble contaminants like gasoline.
· Techniques like SVE and soil washing are mobilization-based methods.