FloridaGreen® encompasses two technologies: Greenhouse Technology & Solar Dryer Pasteurization. 

Greenhouse Technology

Greenhouses are effective when removing moisture from biosolids when conditions are controlled. To control the conditions, we fully enclosed our greenhouses (also called pods) and placed ceiling fans inside to stir the air. Each of our pods is about an acre and a third. The fans enhance the evaporation effect of the biosolids. 

We also have activated carbon systems in our greenhouses that are doing two things. 

1. Removing odor and cleaning the air

2. Removing moisture

In order to make our greenhouses safe to work in from a labor standpoint, we needed to have 6 exchange rates per hour, according to the NFPA 820 code. FloridaGreen has 12 exchange rates per hour — which means every 5 minutes, we are exchanging air in the greenhouses. 

As we dry the material, we lay it across the floor in the greenhouses and we agitate the material with a tractor and a tillage tool called a “folk”. The folk takes the dry, crusted material on the surface and rolls it underneath the wetter, moister material. We stir the biosolids 3-4 times a day. As the biosolids are drying, we are reducing the volume in the greenhouses. Our target dryness is 60% solids. By the time we reach our goal of 60% solids, we have reduced the original volume down by about 33%. 

Solar Dryer Pasteurization

The material is transferred from the greenhouses to our process building with our conveyer system. Once it reaches the process building, it is pulled into a stainless steel unit. From the stainless steel unit, the product is pulled up with a conveyor belt and dropped into the Belt Dryer. The top chamber of our Belt Dryer is called our “Heat Up Chamber”. 

The Heat Up Chamber is where we’re placing the material 2-3 inches thick on the belt and forcing hot air up through the material. The air is being blown through with a rate of 30,000 CFMs. The air flow is assuring the material is evenly being heated. We’re simply pre-heating the biosolids material to bring it up to pasteurization temperature in a single pass operation. The temperature is being brought up to 70 degrees Celsius or 158 degrees Fahrenheit in the Heat Up Chamber. 

As the material reaches the end of the top chamber, we have two options: 

1. Reach Temperature at the End of Belt 

2. Reach Temperature Halfway & Increase Belt Speed

Once the material reaches the end, it drops down into the lower chamber, called our Pasteurization Chamber. The Pasteurization Chamber has a similar design to the Heat Up Chamber, however the belt speed never moves faster than 30 minutes (meeting the pasteurization qualification). As the material reaches the end of the Pasteurization Chamber, it drops down to another conveyor belt, which leads out to the Load Out Building. The Load Out Building is where we can load a trailer or bulk store the material.

Pelletization Process

Following pasteurization of biosolids, the material is very inconsistent in size/shape. Pelletizing forms the biosolids into an easy spreading fertilizer for homeowners and farmers. The process starts with the biosolids being conveyed into the top pellet chamber, where rollers force the biosolids through the pellet die holes. On the underside of the die, blades cut the pellets to length. This process generates a lot of heat from the friction caused from the rollers contact to the die. 200-degree Fahrenheit pellets are discharged on a screening table to remove any dust or oversize material. The pellets are transferred to a cooler where they spend 10-12 minutes under a blower to prevent them from self-combusting. Once the pellets are cooled, they are conveyed to the bagging equipment, where they are bagged, palletized, and warehoused until being shipped to a retail store.

Why Pelletize?

When Class A, exceptional quality (EQ) biosolids are produced using a drying or thermal process, the end product can often contain varying amounts of dust. A dusty product can create issues related to uneven spreading patters, drifting and improper  nutrient placement.

How Does Pelletization Happen?

When biosolid fertilizer is pressed through specially designed dye plates, the friction of the process produces heat. At the proper temperature, the naturally occurring lignen in the biosolids is released to help in the formation of the pellet. Lignen is a complex organic polymer found in the tissue of most plants, therefore it is naturally present in biosolids.