A3.10.6.2 Physical Options


Physical treatment technologies refer to the processes which are designed to separate and concentrate various components of site contaminants without chemically altering the form of these components. Sedimentation is an example of this process.


Chemical Options

Chemical treatment, such as oxidation, refers to a process which brings about a chemical transformation of one or more components of contaminants as the primary means of either removing a particular component or reducing its toxicity.


A3.10.6.3        Physico-chemical Options


Physico-chemical options are a combination of both physical and chemical processes.


Solidification and Stabilization

Hazardous waste is encapsulated into a solid material of high structural integrity. Solidifying fine waste particles is termed microencapsulation, whilst macroencapsulation solidifies wastes in large blocks or containers. Stabilization technologies reduce a hazardous waste’s solubility, mobility, or toxicity.

Solidification and stabilization are effective for treating soils containing metals, asbestos, radioactive materials, inorganics, corrosive and cyanide compounds, and semi-volatile organics. Solidification eliminates free liquids, reduces hazardous constituent mobility by lowering waste permeability, minimizes constituent leachability, and provides stability for handling, transport, and disposal.


Soil Vapour Extraction

Soil vapour extraction is a technology that has been proven effective in reducing concentrations of VOC and certain semi-volatile organic compounds. Principally, a vacuum is applied to the soil matrix to create a negative pressure gradient that causes movement of vapours toward extraction wells. Volatile contaminants are readily removed from the subsurface through the extraction wells. The collected vapours are then treated and discharged to the atmosphere or where permitted, reinjected to the subsurface.


Soil Washing

Soil washing technology involves mixing water and contaminated soil in an extractor vessel. The mixing dissolves the organic contaminant into the solvent. Solvent and dissolved contaminants are then placed in a separator where the solute and solvent are separated and treated. The soils can be stockpiled, tested and used as inert material.