Metals Remediation Compound
Metals Remediation Compound (MRC™) is a controlled release product that simultaneously removes a range of dissolved metals from groundwater via in-situ immobilization and provides a substrate for biodegradation of chlorinated compounds. MRC™ is a non-toxic proprietary organo-sulphur and polylactate polymer compound that is manufactured as a viscous gel. When hydrated it slowly releases its active ingredient, a benign organic sulphur compound (OSC) as well as lactate. The OSC stimulates in-situ metals immobilisation, binding the metals into the aquifer matrix as mineral solids.
When MRC™ is hydrated and becomes subject to microbial biodegradation it slowly releases the OSC. When the OSC comes into contact with dissolved metals such as arsenic, cadmium, cobalt, copper, lead, mercury, nickel, and zinc, a rapid and irreversible reaction occurs that creates metal-organic complexes (MOC's). The MOCs bond strongly to soil particles and become immobile. Over time, the indigenous micro-organisms biodegrade the organic portion of the MOC. The residual compound is an immobile and insoluble sulphide solid. The OSC in MRC™ also acts as a direct reducing agent for metals such as hexavalent chromium which precipitates as Cr(OH)3 when it is reduced to the trivalent state Cr(III)+.
MRC™ continues to release the OSC and also to generate dissolved hydrogen for 12 to 24 months depending on aquifer conditions, thereby removing any additional metals that may come into its zone of influence and maintaining accelerated contaminant degradation rates throughout this period.
Essentially, since MRC™ is a "food grade" material there are no toxicity issues related to it. Since the volume used is relatively small (approx. 0.5% of the application area pore space for a recent Provectus project), it will not displace contamination (e.g. push it to new areas) or interfere with natural groundwater flow characteristics.
In the long term, when MRC™ has released all its active material, no residue remains. The released components will spread and biodegrade as they undertake their designed functions, leaving no residue.