A patented new leading-edge technology for decontamination of water and soil using humic substances (HS) provides an effective, cost-efficient solution. The application utilizes permeable reactive barrier (PRB) that is installed by injection to facilitate subsurface interception, retention and treatment of groundwater contaminants released by industrial and agricultural sources.
This new technology was developed by the University of Florida and Lomonosov Moscow State University.
Once installed, the system operates passively, without active pumping, to decontaminate water flowing (aquifer, pollutant plume) from contaminated soil and subsurface pollutant sources without producing any kind of additional contaminates. It replaces expensive techniques such as the pump-and-treat method for water treatment and plume capture, which further disturbs the surrounding environment.
This innovative method provides for the in-situ installation of humic barrier that can be used as a passive remediation system to treat both organic compounds and metal ions either singly or in combination. In addition, this method can be used to treat viral/bacterial pathogens.
Features
Humification is the chemical-microbiological process of transforming debris from living organisms into a general class of refractory organic compounds, otherwise known as HS. HS account for 50% to 80% of the organic carbon of soil, natural water and bottom sediments.
HS are ubiquitous in the environment and comprise the most abundant pool of nonliving organic matter. Their peculiar feature is polyfunctionality, which enables them to interact with both metal ions and organic chemicals. The palette of potential interactions includes ion exchange, complexation, redox transformations, hydrophobic bonding, etc. As a result, numerous studies have shown humics capable of altering both the chemical and the physical speciation of the ecotoxicants (ET) and in turn affecting their bioavailability and toxicity. HS hold great promise functioning as amendments to mitigate the adverse impacts of ET and as active agents in remediation. The structural heterogeneity of humics may explain their resistance to biodegradation as their longevity in soils is typically on the order of thousands of years. The recalcitrant nature of humics is of practical relevance particularly when the objective is to develop soil/aquifer remediation technologies predicated on a reactive matrix that is not consumed by microorganisms during remediation.
PRBs are replaceable or permanent units installed across the flow path of a contaminant plume. The plume is allowed to migrate passively through the PRB; in the process, contaminants are precipitated, absorbed or degraded.
Humic-based materials show considerable promise as refractory and inexpensive reactive PRB components. This is particularly true wherever remediation involves a complex array of contaminants, and the reactive material must treat both soluble heavy metals and hydrophobic organics.
Functions
One advantage of HS is the low cost of materials. Another is that HS are biologically recalcitrant and not expected to support microbial growth.
Given the biocompatibility of humics together with their resistance to biodegradation, solidified humic matrixes represent ideal sorbents for bacteria and can be inserted into a monitoring well with little concern for possible negative repercussions.
HS can perform multiple functions within a remedial strategy. For example, HS can function as: binding agents and detoxicants; sorbents and flushing agents; redox mediators of abiotic and biotic degradation; and nutrient carriers, bioadaptogens and growth stimulators. With the above functions characterized, it is then proposed that humic-based products hold great promise as reactive agents for in-situ remediation. The most promising technologies include enhanced bioremediation, permeable reactive barriers, in-situ flushing and phytoremediation.
This new method using HS provides an affordable solution to the expensive, growing problem of ecological waste. Other contaminants that can be remediated are plutonum, petroleum products, halogens, heavy metals, industrial solvents, agricultural and viral/bacterial pathogens.
Using example methods of chemical modification described herein, it is proposed that the properties of humics be tailored to satisfy the needs of a given remediation technology. It is expected that the utility and the value of humics will expand.
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