Is human waste the source of nutrient overload impairing Florida waterways? Does land spreading of biosolids from urban areas unfairly impact rural areas?
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Is human waste the source of nutrient overload impairing Florida waterways? Does land spreading of biosolids from urban areas unfairly impact rural areas?
In June, 1000 Friends of Florida released information gathered in a grant-funded study about land spreading of biosolids in the state of Florida.
Biosolids are human waste, processed with heating, composting, digestion or increased pH to reduce pathogens. Class B are the least processed. Class AA are the most processed, and can be sold as fertilizer for home use.
“The land application of solid residues from sewage treatment plants (known as biosolids) has long been controversial in Florida and increasingly throughout the U.S.,” the 1000 Friends of Florida website explains. “Regulators and public health and environmental advocates have raised concerns that nutrients, toxic metals and chemicals in these residues might pollute surface or groundwater and thereby affect the integrity of ecosystems dependent on those receiving waters.”
The study found that major producers of biosolids are Broward, Miami-Dade, Hillsborough and Orange counties. Major receivers are Osceola and Polk counties.
1000 Friends of Florida produced a webinar in which consultant Craig Diamond, environmental economist Dr. Chris De Bodisco, and Florida State University PhD student and researcher Elio Fernandez review current biosolids management, and preview findings the ongoing project.
Diamond said there has historically been a significant transfer of nutrient load from the urban areas of South Florida to the more rural areas of Central Florida.
Biosolids are the solid, organic matter recovered from sewage treatment processes, he explained. They may be referred to as sewage sludge, septage, wastewater residuals or wastewater solids.
Biosolids are separate from effluent, which is the liquid part of the waste stream, he added.
He said when they talk about the land application of biosolids “agricultural use is not the only game in town.”
Disposal of biosolids can include: Land application; landfill; thermal conversion; compositing or injection.
Land applications of biosolids are regulated, he explained. The federal law deals with heavy metals, not nutrient load.
He said the beneficial use of biosolids as fertilizer depends on the treatment process and the standards required. He said heavy metals and contaminants of emerging concern (CECs) can make waste unsuitable for fertilizing crops.
Class B is tracked. Class AA distribution is not actively monitored.
The Northern Everglades and Estuaries Protection Program stopped land spreading of Class B biosolids in the Lake Okeechobee watershed, he explained.
He said the nutrient management plant for the Lake Okeechobee, St. Lucie River and Caloosahatchee River watersheds required “that you must export more nutrients than you apply.”
Fernandez said Florida’s population is growing at about 1.7% per year and tourism is growing at nearly 3% per year.
The current estimated production of biosolids in Florida is 365,400 dry tons per year – about 7.5% greater than Department of Environmental Protection’s estimate in 2018.
The use of land spreading Class B biosolids has declined since 2013, he said. (The Florida Legislature banned the practice in sensitive watersheds in 2010, allowing for a 3-year period to phase in the restrictions.)
About 115,000 dry tons of Class B biosolids were land-applied in 2013; compared to about 80,000 dry tons Class B biosolids land-applied in 2021, he said.
There are 130 Class B permitted application sites in the state, ranging from zero to 52 square miles. Most sites cover less than 5 square miles.
There are eight application sites larger than 5 square miles. These are in Osceola, Brevard, Indian River, DeSoto and Charlotte Counties.
Total Class B biosolids application area by county in Florida totals 158.4 square miles.
The counties with the largest areas for biosolids application are:
He said Polk County has the most land spreading sites with 24. Osceola County is in second place with 9.
Looking at Class B application by volume, Osceola and Polk again top the list of counties land spreading more than 1,000 dry tons per year:
He said 66 landfills accept biosolids.
About half the Class B biosolid production comes from Broward, Miami-Dade and Hillsborough counties. Counties producing more than 1,000 dry tons of Class B biosolids are:
Counties producing more than 5,000 dry tons of Class AA biosolids per year are: Sumpter, Orange, Palm Beach, Indian River, Hendry, Broward, Duval, Pinellas, Hillsborough, Escambia, Charlotte and Okeechobee.
Diamond said the results released in June are preliminary. They will continue to respond to and incorporate comments from the Technical Advisory Committee.
Nutrient management continues to be a problem throughout the state, he explained. More people moving into the state means more waste will be produced.
For more on the study, go online to https;//1000fof.org/biosolids/
What happens to solid waste from Lake Okeechobee area counties?
Okeechobee Utility Authority Executive Director John Hayford said OUA primarily receives domestic wastewater flows so to end up with Class AA quality sludge is expected. He said waste treatment plants that receive industrial waste streams may include heavy metals which are not allowed in Class AA.
OUA sells or gives the waste material to a fertilizer distributor to work it into their product, he explained. “The revenue stream is minimal and not a concern. Where the OUA saves money is that the fertilizer distributor pays to load the trucks and transport the material to their facility. If the OUA wasn’t selling/giving the material to the distributor, then the OUA would have to pay for loading, transport and the disposal fee at the landfill. In essence, the OUA is ‘making’ money by not spending money.”
The City of Clewiston has a contract with Synagro to dispose of biosolids. Synagro contacted the city in 2024 and proposed the Osceola Organics facility for bio-solid disposal. The city received confirmation from Florida Department of Environmental Protection that the facility is a permitted bio-solids treatment facility before entering into the agreement.
According to a Synagro representative, “Synagro hauls the dewatered bio-solids from the Clewiston Wastewater Treatment Plant to Osceola County for composting.
“Last year, Synagro managed 682 wet tons or 136 dry tons (with 20% solid cake) of biosolids for the city. The services totaled $116,388 for all of the sludge dewatering and hauling and disposal of the bio-solids.
“Bio-solids go to a compost facility.
“Bio-solids composted are treated to Class A and/or Class AA. When the material is treated to Class AA the compost stays at the facility and is land applied for sod farming.”
LaBelle used to send the Wastewater Treatment Plant sludge to a Lee County landfill as Class A solids, Joseph Thomas explained.
“The past several years, LaBelle has been using Synagro. LaBelle provides electrical, water, and a return line for supernatant (the clear liquid separated from solids in a centrifuge).
“Synagro provides a centrifuge supported by a truck. A second trailer is used to catch and haul the solids. The water extracted returns to the headworks of the plant. I believe Synagro hauls the solids to Charlotte County facility.”
