Biosolids Management

The Solution

GeoEnvironment Technologies has developed, patented, and successfully demonstrated an innovative new technology to manage municipal sludge with significant environmental benefits. We call this technique Deep Earth Digestion / Sequestration. Through appropriate geological formation selection, well design, and advanced geophysical monitoring, the biosolids slurry can be injected into soft, porous, sand formations in the deep subsurface (on the order of 5000ft or more).

Deep underground the earth’s natural geothermal heat sterilizes the biomass quickly (within 24 hours), and then through continuing anaerobic biodegradation converts the organic mass to methane and carbon dioxide. The carbon dioxide is preferentially absorbed by formation waters (due to its high solubility in water) while relatively pure methane collects and may be stored long-term, or eventually produced for beneficial use.

Recycling Municipal Waste to Energy

At the high temperature and pressure conditions in the deep subsurface, carbon dioxide is ten times more soluble in water than methane. Therefore, as the gas percolates through the formation water, the carbon dioxide will be preferentially absorbed by the water, leaving a relatively methane rich gas phase. Due to density segregation, the gas will percolate upwards through the brine filled porous sand formation until it reaches the impermeable capping shale formation. The resulting relatively pure methane gas can be stored for subsequent beneficial use at the subsurface, in the same way biogas generated from surface digesters is currently used at many modern sanitation plants.

Geothermal Treatment Technology* Summary

1. Inject municipal sludge into deep geologic formations (5000 ft).
2. Allow material to undergo natural process of high-temperature anaerobic biodegradation, which sterilizes the material within 24 hours.
3. Over time (30-60 days), material starts conversion to methane and carbon dioxide.
4. Design process to capture and sequester generated carbon dioxide in formation water.
5. Store or recover high purity methane for beneficial use.

Environmental & Economic Advantages

Enhanced treatment and sterilization of biosolids.
Greater protection for surface and shallow groundwaters.
Provides a local solution, reducing long distance truck traffic.
Reduced greenhouse gas emissions to the atmosphere.
Recycles waste into high quality clean energy for beneficial use.

Frequently Asked Questions

Will this project risk contamination of drinking water? No.

This is non-hazardous material that is currently approved for application directly on the land surface. Placing material 5000 ft below ground is inherently more protective of surface and groundwater than placing it on the surface. The heat in the subsurface provides almost immediate sterilization. Geologic setting (impermeable confining layers), well design (multiple casings), and continuous monitoring practices will ensure confinement in target intervals.

Will this project cause an earthquake? No.

Earthquakes result from destabilization of faults in the earth’s hard crust basement rock. We conduct our injection projects in the soft sedimentary layers far from the basement rock which can absorb the injection through grain realignment or elastic and plastic deformation. A good analogy is that if you hit glass with a hammer, it shatters (because it is brittle), while if you hit beach sand with a hammer, the grains realign such that you don’t feel the sand move if you are even inches away.

As an example, for our TIRE project, planned injection represents less than 3% of current injection taking place in the Wilmington Field. Past injection has been extensively monitored by City of Long Beach and Southern California Earthquake Center for more than 20 years with no activity other than natural seismicity in area. Injection interval is soft, aseismic, and relatively shallow (earthquakes in LA Basin generally are deeper than 20,000ft). Average formation pressure will not be significantly elevated.

Will this project increase air pollution? No. Quite the opposite!

Our technology can be co-located at wastewater treatment plants, meaning that all pollution associated with trucking can be eliminated. In addition, when spread on the ground (land application) or placed in a landfill, biosolids will decompose into CO2 and methane which vent to the atmosphere. These gasses are pollutants with powerful greenhouse effects driving climate change. Our technology permanently traps these decomposition by products in geologic formations and thereby eliminate their emissions entirely. If a community desired, the methane can be produced through a well as a renewable source of natural gas for generating power.

As an example, as of 2016, our TIRE project in California had eliminated more than 1.8 million miles of truck traffic. At our current rates, we eliminate nearly 500,000 road miles each year and sequester nearly 115,000 metric ton equivalents of CO2 each year.

Does this technology save energy? Yes!

Installing a Deep Earth Digestion / Sequestration system at a wastewater treatment plant reduces or eliminates the energy required to: de-water or dry biosolids, to thermally treat biosolids to Class A standards, and to truck biosolids for disposal. Additionally, if economically viable, methane can be recovered for use at sanitation plant providing a potential source of renewable energy.

Why evaluate this technology? The status-quo is not good enough and is not sustainable!

Using Deep Earth Digestion / Sequestration for beneficial reuse of biosolids and greenhouse gas sequestration dramatically lowers capital and operating costs while:

Improving environmental protection of surface and groundwater.
Reducing air pollution and greenhouse gas emissions.
Providing energy savings.
Allowing large urban centers to responsibly manage their biosolids, locally and more cost-effectively, while reducing their impact on the environment.

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