Bio-Remediation
PureAg’s green chemistry and microbiology products are presently used in the bio-remediation industry. Bio-remediation has been broadly defined as the use of biological processes to restore contaminated segments of the environment. Within the waste treatment industry, bio-remediation typically refers to the use of microbes (bacteria, algae or fungi). For many years, this technique has been used successfully to treat sewage, chemical, petroleum, explosive, paper and food processing wastes. The market for bio-remediation has been growing steadily over the last several years, with the use of new technologies at declining prices. In many instances, bio-remediation has proven to be the most cost-effective method to treat soils contaminated with heavy organics, including the ability to break down toxic substances in situ into harmless constituents. Some estimates have shown that bio-remediation can cost as little as 1% of off-site incineration and in many circumstances it is the only economically viable alternative. PureAg’s green chemistry and microbiology products provide technical and economic improvement over other soil washing approaches.
Bio-remediation is relatively more advanced in Europe than in the United States owing, in part, to the relative scarcity of land for disposal of toxic contaminants. PureAg’s technology for soil decontamination has proven to be effective and economically viable in Germany in more than 90 assignments, to clean more than 650,000 metric tons of soil, contaminated with hydrocarbons, phenols, PCBs and dioxin. The methodology has been evaluated by the independent DVGW Forschungsstelle Institute which is charged by the German government to monitor soil clean up. Their evaluations have concluded that the technology is "an elegant and unique decontamination method for organic hydrocarbons".
Methodology
The principal technology is a unique blend of non-toxic surfactants, emulsifiers and nutrients which break down pollutants (including hydrocarbons) into smaller units, emulsify them, and then coat them in a nutrient. The resulting stable emulsion is highly attractive to bacteria. The emulsion is rapidly consumed, easily digested and the resulting fluid is rendered free of pollutants. The hydrocarbons are broken down into non-toxic end products (carbon dioxide, water and biomass). The rate of the treatment process is enhanced by the addition of oxygen or air, which speeds the multiplication of bacteria. Special strains of pollutant consuming bacteria further speed the consumption of the emulsified pollutants.
Soil cleaning is accomplished by excavating the contaminated soil and loading it into a specially designed container. The soil rests on a perforated steel plate placed several inches above the floor of the container. Water and the surfactant are introduced from below, followed by compressed air. The compressed air provides the mixing force required to put the surfactant and the contaminants into physical contact. After approximately forty minutes of mixing, the hydrocarbon contaminants have been separated from the soil matrix, emulsified, and are primarily found in the liquid medium. This liquid is then drained from the container and the soil is removed from the container (if additional removal of contaminants is required, the soil can be rinsed or rewashed with the surfactant). The soil is placed in temporary storage until the results of testing confirm that the soil meets the standard, which allows it to be redeposited at the site. The wastewater is treated at the site in a portable bio-reactor and sent to an existing sewage treatment system or released to the environment. If the contamination was restricted to hydrocarbons, the wastewater will be fully biodegradable, and can be treated as a standard organic waste. The soil will be biologically alive with a healthy population of micro-organisms.
The soil cleaning equipment and bio-reactor can be operated on a twenty-four hour basis with a crew of two persons per shift. A third equipment operator is required to excavate contaminated soil, load the container and redeposit the treated soil. Mobile, truck mounted, soil cleaning equipment ranges in size from 10 to 40 tons capacity per batch (per hour). Bio-reactors are trailer mounted. Their capacity depends solely on the total load of soil contamination, i.e. the BOD of the resulting emulsion.