VoteWater Deep Dive: What is Florida going to do with all this sewage sludge?

The Florida Legislature has taken a step to address one of the state’s nastiest and fastest-growing environmental problems.

The problem is that this attempt to solve one problem may well create another.

As the legislative session wound down last week, lawmakers passed House Bill 1405, which addresses the disposal of “biosolids” — a bureaucratic, science-y sounding euphemism for “sewage sludge,” the nasty stuff left behind at the sewage treatment plant after the treated effluent is released.

About 412,000 dry tons of biosolids are produced in Florida each year, according to the National Biosolids Data Project. Note that’s “dry tons.” The stuff coming out of sewage treatment plants is 80% to 85% water, so the amount of wet sludge is more than 30 million tons.

With about 1,000 people moving to Florida every day, and with each person creating about 1,000 gallons of wastewater a day, as well as millions of tourists visiting the state each year, the amount of sewage sludge in the state will continue to grow dramatically.

Right now, about a third of the sludge is sent to landfills and about two-thirds is used as fertilizer, either as:

  • Class B biosolids, which is partially treated at the sewage treatment plant to reduce the amount of pathogens.
  • Class AA biosolids, which is treated to remove most, if not all, pathogens.

Legislation watered down

Class B biosolids entering the Merrell Bros. Inc. facility in Pasco County are about 80% to 85% water; the finished Class AA biosolid fertilizer is about 10% water. Photo courtesy of Merrell Bros. Inc.

House Bill 1405, by state Rep. Kaylee Tuck, originally had two goals:

  • Prohibit spreading Class B upstream of impaired water bodies, unless the applicant could prove it wouldn’t increase the nutrient load.
  • Create a grant program to encourage wastewater treatment plants and other facilities to process their Class B biosolids into the cleaner Class AA.

But ultimately a strike-all amendment scuttled the language prohibiting DEP from authorizing application site permits for those Class B biosolids. Tuck defended the change, saying “this is the perfect example of not letting perfect get in the way of good.”

But in fact there’s nothing “good” about Class B biosolids.

The federal Environmental Protection Agency has found more than 700 pollutants in Class B biosolids since the agency began tracking them in 1993. The types and amounts of pollutants vary depending upon inputs to individual wastewater treatment facilities.

In 2020, the Florida Department of Environmental Protection identified Class B biosolids as a potential source of Per- and Polyfluoroalkyl Substances (PFAS), a.k.a. “forever chemicals,” because they don’t naturally break down in the environment. They’re highly toxic to humans and wildlife and have been linked to a variety of health effects including high blood pressure, cancer, liver disease, kidney disease and harm to reproductive and immune systems.

Typically, Class B biosolids aren’t so much spread on fields as fertilizer as dumped to get rid of the stuff.

The state currently limits where Class B biosolids can be dumped — banning, for example, their use in the Lake Okeechobee, Caloosahatchee River, and St. Lucie River watersheds. That’s good for those areas, but it leaves land in all the state’s other watersheds particularly vulnerable, as less space available for dumping means more dumping in the space that’s still available.

Failing to expand the ban was a big mistake. Rule No. 1 in plumbing is: The let’s say “stuff” goes downhill. The same is true with the state’s plumbing system. The “stuff” dumped upstream of an impaired water body, or any water body, is going to go downhill and further impair that water.

Class AA biosolids – better but still bad

After leaving a first round of drying in greenhouses, biosolids at the Merrell Bros. Inc. facility in Pasco County are carried by conveyor belts through ovens that heat the material at 158 degrees for 30 minutes to remove pathogens. Photo courtesy of Merrell Bros. Inc.

Class B biosolids are bad, but you don’t have to squint very hard to see that Class AA biosolids also have problems: They contain nitrogen and phosphorus, the nutrients that can feed algal blooms.

The state has an elaborate — although its effectiveness is questionable — record-keeping system to track how much Class B biosolids are dumped and where. No such tracking system is in place for Class AA biosolids.

The state keeps tabs on how much fertilizer of all types is sold in each county, and Class AA biosolids are treated like any fertilizer you buy at a garden store: You’re encouraged not to over-apply, but no one knows if you do or not.

Even without incentive grants, production of Class AA biosolids fertilizer is already on the rise. The state DEP reports that 232,322 dry tons of Class AA biosolids were produced at about 40 plants in the state in 2018 compared to 197,115 dry tons in 2016 and 158,576 dry tons in 2013.

One such plant is a cooperative effort with Pasco County and Merrell Bros. Inc. that uses a solar greenhouse and ovens to turn about 50,000 tons of sewage sludge that’s 82 to 84 percent water into about 9,000 tons of Class AA fertilizer, known as FloridaGreen, that’s 80-plus percent solid, the consistency of dry dog food.

Blake A. Merrell, who helps run the Class AA biosolids fertilizer plant in Pasco County, told VoteWater tracking the use of Class AA biosolids is unnecessary because the market would be self-regulating, that unlike Class B biosolids, which are dumped on fields at no cost to the landowner, Class AA fertilizer is bought by the landowner.

FloridaGreen is delivered to farmers for about $50 to $80 a ton, depending on how close it is to the Pasco County facility. So a farmer with a 40-acre pasture who applies 2 tons of fertilizer per acre (an amount Merrell said was typical for a first-time use and would decrease over time) would pay from $4,000 to $6,400.

“No rancher, farmer or fertilizer buyer is going to over-apply or wastefully spread something they are having to pay hundreds or thousands of dollars for,” he said.

But that’s wishful thinking at best. Florida’s program to prevent pollution by assuming farmers are using “best management practices” has failed miserably at stopping fertilizer runoff from polluting the state’s waterways. Why would the use of Class AA biosolids fertilizer be any different?

Besides, government programs that dole out taxpayer dollars routinely have reporting requirements to show how the money is spent and determine the program’s efficiency.

How much more?

Class B biosolids brought to the Merrell Bros. Inc. facility in Pasco County is first dried in 65,000-square-foot solar greenhouses. Photo courtesy of Merrell Bros. Inc.

Spurred by the legislation’s grant program, the already growing production of Class AA could expand significantly; and more — but who knows how much more? — sewage sludge-based fertilizer would end up on pastures, sod farms and lawns.

For the sake of Florida’s water, any increased use of Class AA biosolids must be monitored.

If legislators want to spend money to process biosolids, they should also look at grants to develop ways to turn the sludge into energy. Less than 1% of Florida’s biosolids (about 1,800 dry tons, according to the National Biosolids Data Project) are used to fuel so-called waste-to-energy facilities.

The more clean uses that can be developed for the state’s increasing biosolids problem, the better.

A facility operated by Merrell Bros. Inc. in partnership with Pasco County can process about 50,00 tons of wet Class B biosolids into Class AA biosolid fertilizer. Photo courtesy of Merrell Bros. Inc.