Our methods
The following are some of the methods we use. As contamination is complex, we usually apply various methods in series or sequence to obtain the optimum outcome. Techniques are in alphabetical order.
Air Sparging
This is in situ sparging of a liquid by a gas to remove dissolved gas from extracted groundwater. Usually a chemically inert gas eg. nitrogen, argon or helium is bubbled through the extracted groundwater which combines with and extracts the less inert gas eg. oxygen, contained in the liquid.
Air Stripping
A technique to remove Volatile HydroCarbons (VHC) from groundwater; volatile contaminants are removed by sheering the liquid within a counter current air flow. Air stripping can involve the use of packed tower strippers or a simpler system of a tower filled with high surface area packing.
Bio Filtration
A technique to extract contaminants from vapour or liquid by passing them through a membrane impregnated with micro-organisms which extract and break down specific compounds.
Bio-remediation Infrastructure
A technique to remediate groundwater where bacteria are used to consume contaminants; often used with pump and treat system. The groundwater is recycled many times to encourage oxygenated water flow and bacteria growth. Care must be taken to avoid bacterial buildup which can reduce filtration and pumping.
Bio-Piles
A technique to reduce contamination of particles by adsorbed phase of contamination eg. Volatile Organic Compounds (VOCs) adsorbed to in soil. The VOCs are vacuumed off to reduce concentration and enable aeration and natural biological degradation.
Catalytic and Thermal Oxidation
A technique to remove contaminants from groundwater by catalyzing conversion into relatively harmless components like Carbon Dioxide, water vapour and salt water. The unit is electrically heated and includes a high efficiency heat exchanger and special precious metal catalyst (often platinum) and results in destruction efficiency of 95-99%. These units are made by Catalytic Combustion Corporation (link to website) and the Remediation Group is the sole Australian agent.
In situ oxidation
An oxidation technique for removal of soil and groundwater contaminants; involves the injection of strong oxidants such as hydrogen peroxide, ozone gas, potassium permanganate or persulfates. Oxygen gas or ambient air can also be injected in a more mild approach.
Multiphase Vacuum Extraction (MPVE)
A technique to remove water, phase separate hydrocarbons (PSH) and soil vapour, from the same well of groundwater, combining Soil Vapour Extraction (SVE) and Pump and Treat Systems. Dewatering of the subsurface also occurs, which exposes previously saturated soils to further soil vapour extraction (SVE). MPVE can be effective for soil and groundwater remediation when the target contaminate is volatile organic compounds (VOC) and when groundwater yield from the aquifer is low. Also known as MPE (Multi Phase Extraction).
Pump and Treat
A technique to treat contaminated groundwater; involves pumping out groundwater using a submersible or vacuum pump, and passing it slowly through a series of vessels containing adsorbant material e.g. activated carbon for petroleum. Flocculants, sand filters and other material may be used to remove contamination.
Soil Vapour Extraction (SVE)
A technique to remove vapour from soil by inducing a flow of air within a geological formation, by utilising an aboveground pump/blower combination. The induced airflow provides a carrier which enhances the removal of Non Aqueous Phase Liquids (NAPL) and provides oxygen to enhance natural aerobic biodegradation.