A pilot project designed to use nanobubble technology for Tijuana River cleanup had to be shut down after trash buildup and flooding wrecked the experiment.
A company report on the project claims it successfully killed pathogens before operations were overwhelmed.
Supervisor Paloma Aguirre addressed the pilot project in the Tijuana River Valley, saying, “the nanobubble project, unfortunately, did fail.”
According to the report, trash and debris during nighttime periods of higher flow clogged the units and restricted operations to daytime hours throughout the pilot. Additionally, installation of the trash boom resulted in a temporary treatment pause.
Then, the report says, significant flooding in mid-October “abruptly halted operations, damaged equipment, and rendered the site unusable for the remainder of the pilot.”
Even so, the report says the technology “consistently produced a very high percentage of pathogen reductions.”
The U.S. Section of the International Boundary and Water Commission (USIBWC) announced the report, prepared by the Ohio-based company Greenwater Services, on Dec. 19 claiming that it “successfully completed” the pilot project, a contract costing $2.5 million which the agency has previously said was funded by the U.S. EPA.
Between Sept. 9 and Oct. 15, the IBWC says it contracted Greenwater Services, to apply its patented water treatment technology — Nano Bubble Ozone Technology (NBOT) providing algae prevention, mitigation and remediation services.
The federal agency says it contracted the company’s patented technology because it was urgent to assess its effectiveness “in addressing the public health threat posed by airborne contaminants in the Tijuana River flows.”
In a news release, the IBWC says it “learned that significant equipment design modifications would be required for an effective scale-up and larger application in the Tijuana River or other similar river systems that exhibit troublesome, unpredictable flow conditions.”
“The IBWC recently completed an ozone treatment pilot project that came up with mixed results, but it showed it was able to kill some harmful bacteria and eliminate some of the odors,” said Supervisor Jim Desmond moments before Aguirre’s remarks in January. “And now the IBWC is seeking funding from partnerships to scale the technology for the extensive needs of the river valley.”
Units washed away
During the project, Aguirre sent a letter to the IBWC expressing concerns that the ozone technology may impact local air quality.
At that time, the agency said it would not slow the implementation of the project because it showed promise in accomplishing a “100% solution to this crisis” identified by the Trump administration in a memorandum of understanding with Mexico.
But the agency’s report details how challenges affected treatment efforts and caused the project to shut down earlier than planned.
On the night of Oct. 14, the equipment being used to treat Tijuana River flows with nanobubble technology was wiped away during a five-hour storm. Floodwater inundated and damaged the NBOT units, including generators and fuel cells, says a report detailing the event.
According to the report, the company cleared hazards and contaminants from the site, including a 5-gallon diesel spill, by Oct. 22.
“Despite substantial operational challenges, including debris-related clogging, limited treatment windows, site access limitations, and an unexpected flooding event, the pilot consistently produced significant reductions in both total coliforms and E. coli levels,” the company claims.
Water treatment results
The report says water quality testing results show significant reduction in total coliform and E. coli concentrations.
Water treatment involves a generator adding nanobubbles with ozone into the water, creating approximately 256 million nanobubbles per milliliter of water, the report explains, which do not rise to the surface nor burst.
The report says ozone inside a nanobubble lasts days, allowing oxidizing agents to break down “toxins and organic contaminants throughout the water column by eliminating or significantly reducing their functionalized molecules.” The oxidizing agents then decompose into oxygen resulting in “oxygenated water.”
For the past six years, the company’s patented technology has been used in canals, lakes, ponds, and rivers.
Across 10 samples collected close to the treatment, the company says there was a 91.5% reduction in total coliforms and 83.8% cumulative reduction in E. coli.
Analyzing four samples collected further away, the company reports an 82.4% cumulative reduction in total coliforms and 89.3% cumulative reduction in E. coli.
Beyond laboratory-verified sampling by the Environmental Laboratory, the report says odor reduction supports the safety of NBOT.
“Throughout the pilot, no adverse effects were reported, and U.S. Customs and Border Protection (CBP) personnel noted a substantial reduction in odors in the treatment area during NBOT operation,” it continues.
The company’s report also notes the absence of adverse environmental or public health impacts during any stage of the pilot.
The expansion of units, integrating a debris filtering strategy and multi-agency collaboration for future considerations to expand the technology in the Tijuana River are among the company’s suggestions in the report.
“With these enhancements, NBOT represents a viable solution for improving river water quality, facilitating beach reopenings, and enhancing public health and community conditions in the surrounding area,” the company concluded.
The project originally was slated to proceed round the clock for approximately 60 days, according to the agency. Instead, it lasted 36 days, and operated only during the daytime for 22 of those days.
Even though the pilot ended prematurely due to flooding, the report asserts NBOT’s efficacy, environmental compatibility and safety during the available treatment windows.
“The USIBWC will continue to investigate and evaluate technologies that can provide relief to U.S. citizens in the region,” said the agency in December. “The USIBWC remains interested in potential funding and application partnerships that can demonstrate cost and operationally large-scale effectiveness.”
