Biosolids: An Annual 700-Million Pound Pollution Source About Which You Rarely Hear

The Coming Population Explosion

At the highest estimate, Florida’s population is projected to increase by 6 million people for a total population of nearly 26 million by 2030. Add to this the projected growth of visitors to our State, and wastewater management should surface as a major concern. The load (capacity) about to be placed on our failing city infrastructures such as sewer lines is frightening.

Florida can also expect that two-thirds of the population growth will occur in just 15 of Florida’s 67 counties. Of the total growth, more than half will occur in just 10 counties 1. The risk is that there will be high growth in just a few places, complicating the wastewater issues even further. This additional wastewater must be treated and disposed of.

The Coming Wastewater Explosion

“Wastewater” is a byproduct of society. Everyone (resident or tourist) flushes a toilet, does laundry, cooks and cleans up, possibly with a dishwasher. Even shower water must be safely carried away because it, too, contains e coli bacteria.

The liquid portion of wastewater, the effluent, can be treated for bacteria and nutrients before being returned to the environment. But, what about the solid portion of wastewater.

Most tourist facilities and two-thirds of Florida’s residents are connected to sewer systems. The raw sewage wastewater (deemed a Biohazard) is transferred via an underground system of pipes to a treatment plant. Here, the liquids are separated from solids.

The liquid portion (called Effluent) is treated, and returned to the environment through spray fields, direct releases into water bodies, injection wells, or distributed as reclaimed water.

But what happens to the solid portion? It, along with the solids removed from septic systems (called Septage), must be treated and disposed of.

These combined wastewater solids, from septic systems and sewers, are captured for treatment and referred to as Sewage Sludge. Sewage sludge is treated to various degrees based on the type of permit issued by Florida’s Department of Environmental Protection to the wastewater treatment facility.

Once treated, the sewage sludge is referred to as a “Biosolids” (sometimes also called cake). But here is where Florida’s challenge begins. How and where they are disposed of after treatment has a huge impact on Florida’s environment.

Quantities of Biosolids

Across Florida, approximately 2,100 of treatment facilities are classified as industrial and approximately 2,000 as domestic wastewater treatment facilities. Just the domestic wastewater treatment plants alone produce 350,000 tons (700,000,000 pounds) of biosolids every year.

How biosolids are made

Biosolids may contain macronutrients, such as nitrogen, phosphorus, potassium and Sulphur; and micronutrients, such as copper, zinc, calcium, magnesium, iron, boron, molybdenum and manganese. Biosolids may also contain traces of synthetic organic compounds and heavy metals, including arsenic, cadmium, chromium, lead, mercury, nickel and selenium. These contaminants limit the extent to which biosolids can be used and, with all applications, they regulated by FDEP and the Federal EPA.

Biosolid Classification & Disposal

Currently, there are three classes of biosolids permitted for beneficial use based on treatment and quality:

  • Class B biosolids are treated but still contain detectible levels of pathogens and is the minimum quality for beneficial use. They account for 30 percent of treated biosolids and are used primarily for landfills.
  • Class A biosolids contain no detectible levels of pathogens. This type of biosolid must meet strict reduction requirements and contain low levels metals of metals. Permits are required from FDEP to ensure that these very tough standards have been met. They are typically distributed to farms as fertilizer.
  • In Florida, we have a third class. Class AA biosolids are treated to eliminate pathogens and heavy metals. These are equivalent to Class A Exceptional Quality (EQ) under EPA regulations. They account for 45 per cent (approximately 200,000 tons) of treated biosolids and are used as both commercial and residential fertilizer across Florida. Thirty-nine of our 2,000 residential treatment plants are permitted to produce Class AA biosolids.

Biosolid Environmental

All Biosolids are high in organic content and moderate in nutrient content (nitrogen and phosphorus). It is important to understand that these are the same nutrients (nitrogen and phosphorus) that impair water quality and feed toxic algae blooms.

It is ironic that these are the same nutrients – the nutrients our State will be spending billions of dollars to remove from our ground water because of the claim that septic systems are polluting our waterways – will be put right back into our environment though the disposal of biosolids.

Biosolids contain approximately 5.5 per cent nitrogen and 2.2 percent phosphorous. Through the land application of biosolids, approximately 4 million pounds of nitrogen and 1.5 million pounds of phosphorus are re-introduced back into the environment every year.

Biosolid Regulation

The location of treatment plants, the location of land application sites, and the amounts of biosolids permitted for a use can greatly affect the impact public health and water quality. Therefore, the placement and use of biosolids is regulated by the Federal Environmental Protection Agency (EPA) and the Florida Department of Environmental Protection (FDEP).

Formerly, these two agencies set standards for the disposal or final use of biosolids generated during domestic wastewater treatment. The standards included general requirements, pollutant limits, management practices, and operational standards for biosolids. Standards were also included for biosolids applied to the land, placed on a surface disposal site, or fired in a sewage sludge incinerator.

In 2010 Florida began requiring site permits for the land application of biosolids. It also began requiring Nutrient Management Plans (NMPs), provisions to govern phosphorus limitations, and site management requirements. NMPs are site-specific plans that specify the rate at which biosolids can be applied in the area, the method of application allowed (i.e. surface application, injection, incorporation, etc.), the zone (location) in which biosolids can be applied, pollutant concentration targets, and cumulative pollutant loading limits from all sources at the application site. NMPs are submitted to FDEP along with the permit application for each agricultural site.

Site Locations for Biosolid Land Fills

Click HERE for an interactive map of the Biosolid Landfill Locations

Agricultural sites, located in an impaired watershed, are required to have an NMP, and are also often required to participate in the Florida Department of Agriculture and Consumer Services (DACS) Best Management Practices program. Typical BMP practices include nutrient management, irrigation and water table management, and water resource protection.

While nutrient management practices for biosolid land applications attempt to address appropriate considerations for their source, rate, timing, and placement of nutrients to minimize impacts to water resources, weather events and rainfall are not controllable. Not even our State government can control rain. Eventually, these same nutrients, taken out of wastewater and applied back on land, will end up leeching back into our environment. It is inescapable and we are producing more and more biosolids every year.

Understanding the Biosolid Lifecycle

The circle of life, the consumption of plants and animals, temporarily moves nutrients from our environment, through the food chain into the human body. Later, these nutrients must be dealt with as we return them to the environment. This displacement process, when not managed properly, leaves us with environmental issues such as algae in our rivers, springs and coastal waters.

This life cycle is not about nutrients directly but where they are and in what concentrations. Humans need them to live, plants and animals need them to grow. Four fifths of our atmosphere is composed of nitrogen. The responsible society will understand this, responsibly manage the use of these nutrients and prioritize how and where to return them to the earth.

What should your concerns be?

As has been shown, biosolid land application sites are distributed across our State and watersheds. They are returning millions of pounds of nutrients back into the environment. In addition, the amount of biosolids converted to fertilizer provide another conduit for reentry of a substantial portion of the nutrients that we have just spent money and resources to remove.

Much of the blame for algae blooms and nutrient pollution has fallen on septic systems. However, failing sewer systems also provide enormous amounts of nutrients into our environment. Additionally, fertilizers and reclaimed water are having their impacts.

As Florida grows, it becomes nearly impossible to ignore the impact of biosolid management. Unless we understand ALL the sources of nutrients, we cannot and will never fix Florida’s water problems. For those seriously concerned about water quality impairment, the disposal of biosolids deserves to become a key part of the discussion.

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Dan Peterson

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