Contaminated Groundwater Treatment

Contaminated Groundwater Treatment - This short paper covers new contaminated groundwater treatment and remediation practices involving “White Karbon”. White Karbon, a revolutionary product was launched at the UK's International Clean Up exhibition.

White Karbon is an alternative material to the conventional Granulated Activated Carbon (GAC) and is designed to treat a wide range of contaminants from groundwater, including petroleum and chlorinated hydrocarbons, metals, cyanides and pesticides. An interesting feature of White Karbon is that, unlike GAC, it is extremely efficient at removing metals, including nickel, cadmium, arsenic and hexavalent chrome. The latter substance has proved hard to remove from groundwater using other treatment methods available.

White Karbon has its roots in the petrochemical industry, where the removal of hydrocarbons from 'produced water' is an important part of the offshore drilling process. Realising that improved filtration efficiency and small environmental footprint are two features that could be a major advantage in land based groundwater and wastewater treatment, White Karbon has been added to the growing list of in situ and ex situ remediation technologies. It is anticipated that local Authorities, consultants and industrial sites that are faced with particularly difficult metal removal problems will benefit significantly from the new material.

GAC works on the principle of physical absorption, where contaminants are effectively trapped within the structure of the material. Unfortunately, it can become saturated, and a phenomenon known as 'kick out' can occur. When a contaminant is absorbed by GAC, energy is given off in the form of heat. If a different contaminant is subsequently released that generates higher amounts of energy, the original contaminant can be released. The 'kick out' can actually increase the amount of a particular contaminant occurring after treatment in extreme circumstances.

Unlike GAC, White Karbon relies on a chemical process to absorb contaminants. Chemical absorption ensures that once a contaminant has reacted with the filtration medium, it cannot subsequently be released, which means a significantly higher mass of contaminant can be removed, per unit mass of absorption material.

White Karbon is able to absorb between 7 and 20 times more contaminant than GAC and because its density is higher than GAC, significantly less material is needed to do the same job. It is also able to treat groundwater with different contaminants in mixed phases more effectively in a single pass. Trials have shown that up to 98% of all emulsified and dissolved oils can be removed in a single pass.

White Karbon is cost effective for the mass removal of most contaminants, although on occasions it can be used in conjunction with GAC, which acts as a secondary polishing agent for reaching non-detect treatment concentrations. In terms of disposal of the spent filtration medium, between 40 and 100 times more volume of GAC is required to perform the same level of treatment. Re-use of the spent media maybe an option with use as an alternative fuel supply for industry.

There are currently three types of material; WK25 is designed for the removal of petroleum and chlorinated hydrocarbons, W40 treats positively charged heavy metals such as lead, cadmium, nickel and zinc, and WK40C has been developed for hexavalent chrome and other metals with negative ions. WK25 is a granular starch based organic material, whereas WK40 is a sodium aluminium silicate that has been activated by the addition of aluminium oxide at high temperature. Because different types of White Karbon can be mixed in the same filtration rig, remediation of a site containing several different contaminants becomes more straightforward.

Extracted from a Groundwork Search & Send publication.

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