ORLANDO, Fla. – Orlando’s utility is barely able to get enough liquid oxygen needed to purify the city’s drinking water even as other urgent worries are peaking.
“We are definitely not out of the woods,” said Tim Trudell, Orlando Utilities Commission spokesman.
Liquid oxygen is in short supply because of the priority and surging demand at hospitals for care of COVID-19 patients. For the past two weeks, Orlando Utilities Commission has implored residents and businesses through mailers and public announcements to conserve water, to little avail.
As a result, daily demand dropped from 90 million gallons to 80 million for more than a week. But late this week, daily consumption has pushed back up to as much 85 million gallons daily.
Even with its own modifications to lessen usage of liquid oxygen, OUC is only narrowly able to meet the demand for water and is increasingly wary of further supply-chain disruptions in addition to those caused by the pandemic.
Availability of liquid oxygen is a moving target pegged to COVID caseloads. But, for now, if a hurricane blocked liquid-oxygen deliveries for a few days, then Orlando residents and businesses likely would have to boil tap water to make it potable. September is the toughest month for hurricane worries.
“This could quickly turn,” said Wade Gillingham, OUC’s vice president for production of electricity and water.
Wade said that reserves of liquid oxygen at OUC water plants, where large tanks hold nearly a two-week supply, have dwindled so that deliveries are now “just in time.”
The utility typically receives 10 tanker deliveries each week. That has been cut to between five and seven delivers per week.
About 7 percent of the nation’s water utilities rely on liquid oxygen, according to data from the American Water Works Association and Environmental Protection Agency.
In 1997, the municipally owned OUC moved boldly into the practice of employing oxygen for treatment of drinking water, a high-end process used by some producers of bottled water.
Many other utilities in the region utilize oxygen but typically at one or a few of their plants. Orange County Utilities, for example, has 11 treatment plants, with one of those using liquid oxygen.
That county plant normally provides 11 million gallons daily but has been throttled back to 5 million gallons daily to conserve liquid oxygen.
Toho Water Authority, serving the Kissimmee area, has 13 treatment plants, with one of those equipped for liquid oxygen. That plant has continued to provide its normal output.
OUC now relies on liquid oxygen at all seven of its plants.
Water pumped by OUC and other utilities from the Floridan Aquifer hundreds of feet underground contains hydrogen sulfide, which occurs naturally from decomposition of organic matter. The chemical infuses aquifer water with color and rotten-egg smell.
Central Florida utilities traditionally have removed hydrogen sulfide by splashing aquifer water down an artificial waterfall, allowing air to strip away unwanted smell and color. The other typical practice is the application of chlorine, which gets rid of hydrogen sulfide.
But chlorine can add foul taste and create hazardous substances when it breaks down impurities.
OUC’s approach converts liquid oxygen into ozone and then injects that ozone into water pumped from the aquifer. Ozone gas behaves in many ways like chlorine, killing germs and removing odors and color, but ultimately decaying away and leaving no residue.
OUC does add a small dose of chlorine, just enough to meet the state’s minimum requirements for disinfection protection as drinking water travels through pipelines to homes and businesses.
Rich Craig, vice president for technical and regulatory affairs at the Compressed Gas Association, said shortages of liquid oxygen have been regional and tied to COVID hospitalizations.
Liquid and gaseous oxygen is used widely in the U.S. for applications varying from rocket propellant to steel making.
But with medical usage related to the pandemic surging, “our members in some parts of the country are seeing demands of three to five times normal,” Craig said.
He said hospitals are reportedly providing COVID-19 patients with 30 liters to 60 liters of oxygen per minute — “which is an incredible amount of oxygen.”
Liquid oxygen is produced by chilling atmospheric air to 300 degrees below zero, when oxygen separates from other gases and liquifies.
“It is transported and stored in what are essentially Thermos bottles, high-tech Thermos bottles, but Thermos bottles,” Craig said.
The chief advantage of liquid oxygen is reduced volume. One cubic foot of liquid oxygen equals 700 cubic feet of gaseous oxygen. OUC needs about 6,000 cubic feet of gaseous oxygen to treat 1 million gallons of drinking water.
Craig said producers have cranked up production but they have been limited also by the availability of drivers for the sudden jump in needed deliveries.
OUC’s primary supplier of liquid oxygen is an international company called Air Products.
“We continue to prioritize hospitals we supply in Florida and have adjusted our industrial gas facilities production processes in order to maximize levels of medical oxygen and deliver many times our normal supply levels, while also being certain to meet the needs of essential customers like potable water suppliers,” said Art George, an Air Products spokesman.
The company has a liquid-oxygen production plant in the Orlando area and is bringing additional deliveries to the region from a plant in Georgia.
For its part, OUC has reduced consumption of liquid oxygen through several adjustments.
The utility is maximizing water production at its plants that pump aquifer water with the least amount of hydrogen sulfide, and is decreasing production at plants where aquifer waters contain higher amounts of the impurity.
OUC has adjusted its process of converting liquid oxygen to ozone, opting for settings that are less efficient because they require more electricity but derive higher volumes of ozone.
The utility has also decreased the pressure of water throughout its system, dropping from roughly about 65 pounds per square inch to 60 pounds per square in an effort to reduce water consumption.
OUC’s primary conservation push is for customers to hold off on watering lawns, washing cars and using pressure washers.
“This is unprecedented,” said OUC’s vice president, Gillingham. “Who would have guessed this type of hospitalization and this type of use of liquid oxygen was going to put a strain on the supply for this length of time?”
Gillingham said the utility will seek additional technologies for water treatment.
“We know we are going to go back and review this and it is going to take some time,” Gillingham said. “You’ve got to have a design; you’ve got to do the economics; and you have to look at associated supply chains. I can commit that we are absolutely going to be looking at options.”
____
