The City of Los Angeles, along with its partners GeoEnvironment Technologies and the US EPA, is demonstrating an innovative technology to convert biosolids into clean energy by deep well placement and geothermal biodegradation. Slurry mixtures of treated, non-hazardous, municipal wastewater residual solids and treated effluent are injected deep into the ground at the Terminal Island Water Reclamation Plant operated by LA Sanitation.
The TIRE project aims to use biodegradation to eventually convert biosolids into methane, carbon dioxide, and nonvolatile solids. The project vision is to harness this methane to produce environmentally safe renewable energy, as well as provide a reservoir to contain carbon dioxide.
The mission of TIRE is to develop a sustainable biosolids management option that is cost-effective, socially acceptable, environmentally sound, and protective of public health and the environment.
The Terminal Island Renewable Energy (TIRE) Project has been running at TIWRP since July 2008. TIRE, which is being demonstrated under a US EPA Underground Injection Control (UIC) permit, places biosolids in depleted deep subsurface oil and gas formations.
At a depth of 5,300 feet underground, the material will undergo a natural process of high-temperature anaerobic biodegradation. The high saline environment treats and converts the biosolids into methane, carbon dioxide, and non-volatile residual solids. The carbon dioxide is then preferentially dissolved and sequestered in the formation brine, while the goal is for the methane to migrate and become trapped in the reservoir in sufficient quantities for use as an environmentally safe renewable energy. Four wells have been drilled to a depth of approximately 5300 feet beneath the TIWRP. Geothermal biodegradation is still being monitored, while we continue to run the project and test for renewable gas production.
The TIRE project is supported by environmental and regulatory agencies, as well as the academic community. The TIRE project benefits are important to the wastewater industry in helping to develop a new and sustainable biosolids management option that is cost-effective, socially acceptable, environmentally sound, and protective of public health and the environment.
So far, TIRE has successfully injected over 200 million gallons of bio-slurry material, which includes brine, treated effluent, digested sludge and re-slurried biosolids. The operations are continuously monitored and data is reported to the US EPA and a Technical Advisory Committee.
This photo shows the initial construction on the TIRE project, including the large piping used for the injection well casings.
A truck dumps wetcake from Hyperion Water Reclamation Plant into a mix tank for slurrification with the digested sludge from TIWRP before injection into a deep well.
A rig at TIRE drills the injection well. The wells go as deep as a mile under the surface of the earth. Three of the four wells are "directional," meaning that although the inlet is in one location the outlet is angled off, sometimes hundreds of feet away, to reach the desired formation below the earth's surface. Two of the wells are used for monitoring, equipped with downhole pressure and temperature sensors to ensure that the well injects occur as expected.
These large pumps and engines push the biosolids deep into the injection wells.
Before the biosolids are injected into the TIRE wells, they are first held in these large egg-shaped digesters in a thermophilic process to break down the sewage sludge.
This photo shows the drilling operations of Well #4 in March 2014.