System and process for reducing PFAS and microplastics in biosolids using hydrodynamic cavitation and foam fractionation

Abstract

A system for reducing particles from biosolids, comprising a storage tank for holding biosolids and an inlet pipe. The inlet pipe delivers biosolids from the storage tank to a screener and then to a percent solids meter. The percent solids meter measures the solid content in the biosolids and sends a signal to an electronic solenoid valve to control water content of the biosolids introduced to the system. A first venturi hydrodynamic cavitation to create vacuum bubbles in the biosolids. A mechanical hydrodynamic cavitation device operably connected to first venturi hydrodynamic cavitation, wherein the mechanical hydrodynamic cavitation device creates vacuum bubbles in the biosolids.

Claims

1. A system for reducing particles from biosolids, comprising: a. a storage tank for holding biosolids and an inlet pipe, wherein the inlet pipe delivers biosolids from the storage tank to a screener and then to a percent solids meter operably connected to the inlet pipe, wherein the percent solids meter measures the solid content in the biosolids and sends a signal to an electronic solenoid valve to control water content of the biosolids introduced to the system; b. a chlorine generator operably connected to the percent solids meter, wherein the biosolids are conveyed through the inlet pipe to the chlorine generator from the percent solids meter; c. a first venturi hydrodynamic cavitation chamber operably connected to the chlorine generator, wherein the biosolids are conveyed through the inlet pipe to the first venturi hydrodynamic cavitation chamber from the chlorine generator and the first venturi hydrodynamic cavitation chamber creates vacuum bubbles in the biosolids; d. a mechanical hydrodynamic cavitation device operably connected to the first venturi hydrodynamic cavitation chamber to receive biosolids through the inlet pipe from the first venturi hydrodynamic cavitation chamber, wherein the mechanical hydrodynamic cavitation device creates vacuum bubbles in the biosolids.

2. The system of claim 1, further comprising a high pressure pump operably positioned downstream of the mechanical hydrodynamic cavitation device, to convey the biosolids to a second venturi hydrodynamic cavitation chamber for introducing vacuum bubbles into the biosolids.

3. The system of claim 1, further comprising a plurality of venturi hydrodynamic cavitation chambers arranged in series downstream of the second venturi hydrodynamic cavitation chamber, wherein each of the plurality of venturi hydrodynamic cavitation chamber disrupts biosolids to reduce PFAS.

4. The system of claim 1, further comprising at least one foam fractionation chamber operably connected to the inlet pipe to receive biosolids from the storage tank after biosolids pass through the first venturi hydrodynamic cavitation chamber and the first hydrodynamic cavitation device, wherein the at least one foam fractionation chamber has a top portion and a bottom floor; a. a plurality of weirs positioned inside the at least one foam fractionation chamber, wherein the weirs act as baffles to direct and control the rate and directional flow of the biosolids; b. a vacuum-blower pump, wherein the vacuum-blower pump applies a vacuum action at the top portion of the at least one fractionation chamber to remove foam and microplastics and to discharge air through at least one air discharge exhaust; c. a plurality of automated drain valves positioned in the bottom floor of the at least one foam fractionation chamber, wherein the plurality of automated drain valves is operable to remove biosolids from the at least one foam fractionation chamber in response to a signal received from a programmable logic control; d. at least one positive displacement blower, wherein the at least one positive displacement blower delivers a plurality of air bubbles into biosolids in the at least one foam fractionation chamber concurrently with the vacuum-blower pump removes foam and microplastics from the top portion of the at least one foam fractionation chamber; e. a plurality of disc diffusers positioned substantially flush with the bottom floor of the at least one foam fractionation chamber, wherein the plurality of disc diffusers agitate biosolids to prevent the accumulation of biosolids on the bottom floor; f. the programmable logic control is operatively connected to the vacuum-blower pump, positive displacement blower, and disc diffusers to selectively control the flow of the biosolids; and g. a dewatering device operably connected to the at least one foam fractionation chamber to receive the biosolids and to remove water from the biosolids.

5. The system of claim 4, wherein a plurality of foam fractionation chambers is operably connected in series.

6. The system of claim 4, further comprising a static mixer operably connected to the inlet pipe to allow the addition of a surfactant to the biosolids.

7. The system of claim 4, wherein the dewatering device is a centrifuge.

8. The system of claim 4, wherein the dewatering device is a belt press.

9. The system of claim 4, wherein the dewatering device is a mechanical press.

10. The system of claim 4, wherein the dewatering device is a screw press.

11. The system of claim 4, wherein the disc diffusers comprise a slit disc diffuser recessed into the bottom floor of the at least one foam fractionation chamber.

12. The system of claim 4, wherein the at least one foam fractionation chamber includes a vacuum hood.

13. The system of claim 4, further comprising a positive displacement pump to introduce a surfactant to the biosolids to aid in the formation of air bubbles.

14. The system of claim 4, further comprising a velocity slowing chamber to reduce the rate of removal of foam from the at least one foam fractionation chamber and to burst the air bubbles to concentrate the foam before the vacuum removes the foam from the at least one foam fractionation chamber.

15. The system of claim 1 further comprising a double drum drying system to receive the biosolids and to remove water content after biosolids are processed through one or more dewatering devices.

16. The system of claim 1, further comprising a disintegration grinder and a continuous flow self-cleaning screen, wherein the disintegration grinder and continuous flow self-cleaning screen remove solid particles from the biosolids.

17. The system of claim 16 wherein the solid particles comprise inorganic particles.

18. The system of claim 16 wherein the solid particles comprise organic particles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a front perspective view of a foam fractionation system for treating biosolids.

(2) FIG. 2 shows a rear perspective view of a foam fractionation system for treating biosolids.

(3) FIG. 3 shows a first side perspective view of a foam fractionation system for treating biosolids.

(4) FIG. 3A shows a cutaway cross section of a foam fractionation chamber with biosolids and foam.

(5) FIG. 4 shows a second side perspective view of a foam fractionation system for treating biosolids.

(6) FIG. 5 shows a third side perspective view of a foam fractionation system for treating biosolids.

(7) FIG. 6 shows a fourth side perspective view of a foam fractionation system for treating biosolids.

(8) FIG. 7 shows a top view of a prior art clarifier tank.

(9) FIG. 8 shows a cross-section view of a clarifier tank.

(10) FIG. 9 shows a close up view of a diffuser.

(11) FIG. 10 shows a schematic of the disc diffusers for a foam fractionation chamber.

(12) FIG. 11 shows a top view of a foam fractionation chamber with an array of weirs and the flow pattern.

(13) FIG. 12 shows a schematic view of a foam fractionation chamber with diffusers flush with the floor.

(14) FIG. 13 shows a perspective view of a static mixer.

(15) FIG. 14 shows adjustable fresh air inlet check valve.

(16) FIG. 15 shows an electronic solenoid valve.

(17) FIG. 16 shows an Solitax HS-Line sc/Immerson 500 g % solids meter.

(18) FIG. 17 shows a vacuum pressure blower.

(19) FIG. 18 shows a pressure transducer.

(20) FIG. 19 shows an electronic valve.

(21) FIG. 20 shows an adjustable slide gate valve.

(22) FIG. 21 shows a continuous flow self-cleaning screener.

(23) FIG. 21a shows a grinder.

(24) FIG. 22 shows a Venturi hydrodynamic cavitation system.

(25) FIG. 22a shows an alternate hydrodynamic cavitation system.

(26) FIG. 22b shows perspective view of one embodiment of a hydrodynamic cavitation device system.

(27) FIG. 23 shows a demister

(28) FIG. 24 shows a perspective view of a venturi hydrodynamic cavitation device.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(29) This description provides contemplated modes of carrying out embodiments of the invention. The description illustrates the general principles of the claimed inventions without limiting their scope.

(30) The WAS solids concentration typically ranges from 1-2% solids (98-99% moisture). Prior limitations to FF of biosolids included plugging or clogging issues related to the high solids content of WAS. The continuous flow percent solids meter 40 measures the solids content of WAS. Through repeated testing, it was determined that biosolids 50 which have been diluted to the level of 1% solids and disintegrated can be subjected to FF for successful PFAS removal. Using the novel components and Programmable Logic Controls (PLC), the disclosed systems perform a method that continuously sends a reading of the percent solids to the electronic solenoid valve 30 that controls the flow of water into biosolids 50 to dilute the biosolids and to maintain the biosolids at about 1% solids, which in turn permits the continuous treatment as herein described. This invention controls the solid content of the biosolids 50 continuously to about 1% so that biosolids 50 can be effectively treated with hydrodynamic cavitation and FF to remove PFAS and microplastics to a desired concentration or level.

(31) Referring to FIG. 1, the system 10 comprises multiple components. Biosolids 50 enter the system 10 through inlet pipe 20. A first valve 30 receives a signal from a continuous flow percent solids meter 40 to control the addition of water to biosolids 50 at a static mixer 60. In one embodiment, valve 30 is an electronic solenoid valve. Biosolids 50 enter a first stage foam fractionation chamber 110. In a preferred embodiment, the system 10 comprises a plurality of foam fractionation chambers 110, 115, 120, 125, and 130. Fractionation chambers 110, 115, 120, 125, and 130 may be constructed from metals, alloys, other suitable materials, or any combination of the foregoing. This specification uses (n) in connection with fractionation chambers 110 to denote that any plurality of chambers 110(n) may be used in the disclosed inventions. Fractionation chambers 110(n) may be of any useful size. In one embodiment, fractionation chambers 110(n) are rectangular in shape, have a height of eleven feet, a width of about 6 feet, and a length of about 9 feet.

(32) Referring to FIGS. 2-6, system 10 is shown with first stage fractionation chamber 110, second stage fractionation chamber 115, third stage fractionation chamber 120, fourth stage fractionation chamber 125, and fifth stage fractionation chamber 130. The first, second, third, fourth, and fifth stage fractionation chambers 110, 115, 120, 125, and 130 are sometimes referenced as fractionation chamber 11(n). Fractionation chambers 110(n) are arranged in series and operably connected with a labyrinth of pipes to allow biosolids 50 be transported to each successive fractionation chambers 110(n) after treatment in the preceding fractionation chambers 110(n).

(33) System 10 further comprises a vacuum-blower pump 90 configured to apply vacuum action to top of fractionation chambers 110(n) to remove foam and to discharge air through air discharge exhaust 380. System 10 also comprises air inlet check valves 390(n), automated exhaust air valves 400(n), a plurality of discharge pumps 410(n) associated with each fractionation chamber 110(n). A plurality of automated drain valves 420(n) are operably connected to pressure transducers 430(n) and programmable logic control 280. Drain valves 420(n) are preferably positioned at the bottom of fractionation chambers 110(n). PLC 280 selectively controls pressure transducers 430(n) so that biosolids 50 may be selectively removed from fractionation chambers 110(n) and piped to optional dewatering systems as described below. This system utilizing the pressure transducers also allows the operator to adjust the level of the foam at the top of the chamber to meet the need of the vacuum that is pulling the foam off by adjusting the overall level of material in the tank.

(34) A positive displacement blower 90 serves as an air pressure mechanism to deliver air bubbles to biosolids undergoing the FF process and as the vacuum mechanism to remove the foam 350 (not shown) from the top of the biosolids 50 in fractionation chambers 110(n). The novel use of positive displacement blower 90 to perform two functions reduces the complexity and operating cost of system 10.

(35) Referring to FIGS. 9, prior art aeration chambers are shown. The claimed inventions overcome problems associated with such prior art systems and correct the problems associated with solids buildup and settling with aeration systems that are part of the FF process. As shown in FIG. 9, prior art systems use an arrangement of diffusers 300(n) and pipes 310(n) positioned above the floor of aeration tanks 320. This arrangement allows sediment to collect on the floor of aeration tank 320, thereby requiring vac trucks or manual cleaning periodically 440 or additional components to agitate or remove sediment from the floor 320. Typically, air diffusers 300(n) have been used for the introduction of air into a body of water. A typical air diffuser installation involves plumbing pipes 310(n) on top of the tank floor 320. Pipes 310(n) comprises a plurality of Tees 330. The diffussers are raised off the floor and they are Teed into the main diffusser header pipe 310.

(36) Referring to FIGS. 10 and 12, in the novel system 10, disc diffusers 140(n) are positioned flush with the chamber floor 145 to eliminate or substantially reduce the potential for biosolids 50 to settle on floor 145. The plurality of diffusers 140(n) are positioned substantially across the entire surface of floor 145. The disclosed inventions inhibit accumulation of biosolids 50 on floor 145 by recessing the diffusers 140 into the floor 145, allowing the diffusers 140(n) to be flush with the bottom of the chamber floor 145. The continuous pressurized air traveling up through the diffusers 140(n) prevents solids 50 or other material from settling onto the floor 145. This novel approach causes substantially all biosolids 50 to move through fractionation chambers 110(n) and ultimately be processed without significant accumulation. Additionally, this structure and method assures substantially complete treatment for PFAS removal from all biosolids 50.

(37) Programmable logic control 100 (PLC) is operatively connected to the components of the system 10 to selectively control the flow of biosolids 50 through system 10. Referring to FIG. 10, foam fractionation chambers 110(n) have a plurality of disc diffusers 140(a-n). The number of disc diffusers 140(n) may vary without departing from the scope of the invention. The disc diffusers 140(n) are positioned at the bottom of fractionation chambers 110(n) to diffuse or separate biosolids 50. The number of diffusers 140(n) may vary depending on the size and construction of fractionation chambers 110(n). Additional features are described in greater detail below.

(38) Disc diffusers 140(n) are positioned on the floor of fractionation chambers 110(n) to allow for the fractionation of thicker biosolids 50 without biosolids 50 precipitating to the bottom of fractionation chambers 110(n) and plugging system 10. Disc diffusers 140(n) impart force on biosolids 50 to continuously blow biosolids 50 off the bottom of fractionation chambers 110(n).

(39) Referring to FIG. 1-6, biosolids 50 are introduced to the system 10 through an inlet pipe 20. A continuous flow percent solids meter 40 measures the solid content of the biosolids prior to entering the system 50. In one embodiment, the percents solids meter 40 is a turbidity and suspended solids immersion probe such as Solitax HS-Line sc/Immerson 500 g/Wiper SS. The biosolids 50 need to be about 1% solids by volume before entering fractionation chambers 110(n). If the biosolids 50 in inlet pipe 20 comprise more than about 1% solids, the meter 40 sends a signal to first valve 30. Valve 50 may be any type of electronic solenoid water valve such as Granzow 2 inch WpB19-000 solenoid water valve or equivalent. The valve 30 is operable to allow water to be introduced into the biosolids 50 in the inlet pipe 20. The meter 40 and valve 30 communicate with each other using electronic signals to determine when a sufficient amount of water has been added to biosolids 50 to reduce the solids content to about 1%. The water is added to biosolids 50 and then travels immediately into a static mixer 60. Once the biosolids 50 are measured by meter 40 to contain about 1% solids, the biosolids 50 travel from the inlet pipe 30 through a series of weirs that intentionally force the biosolids to flow back and forth to increase the dwell time they are in the chamber 70.

(40) Once appropriately diluted, the biosolids 50 are introduced to a first stage foam fractionation chamber 110. Inside this first stage FF chamber 110, a plurality of disc diffusers 140(n) are positioned at the bottom of chamber 110. In a preferred embodiment, each disc diffuser 140 may be about 9 inches in diameter and comprises a plurality of slits to permit air to pass through the diffuser 140. Diffusers 140(n) are recessed into the floor of the chamber 110 so that diffusers 140(n) are positioned flush with the bottom of the chamber 110. The diffusers 140(n) are commonly sold through SS Aeration Co. or similar vendors. In a preferred embodiment, selecting 2 mm slits increases the effectiveness of the FF process by limiting the size of the air bubbles. Limiting the size of the air bubbles increases the aggregate surface area of all the air bubbles in the chamber 110. Maximizing the aggregate surface area of the bubbles allows for greater absorption of PFAS in the bubbles. Diffusers 140(n) pump about 5-15 cubic feet per minute (cfm) of compressed air using a positive displacement blower into each diffuser 140(n). In one embodiment, a Roots 36URAI or 711 URAI type blower is used. Depending on the size of the FF chambers 110(n) other types of blowers 90 may be used. The compressed air creates bubbles that travel through biosolids 50 in fractionation chambers 110(n). During this bubbling, hydrophobic PFAS compounds and microplastics release from the biosolids 50, attach to the bubbles, and the bubbles take the PFAS compounds to the top surface of biosolids 50 in fractionation chambers 110(n).

(41) Referring to FIG. 11, an exemplary fractionation chamber 110(n) is shown. Fractionation chambers 110(n) will be substantially similar in design and function. However, the disclosed inventions encompass systems 10 in which fractionation chambers 110(n) may be of different sizes and configurations.

(42) Inside fractionation chambers 110(n), a plurality of weir plates 170(n) are positioned. The weir plates 170(n) act as baffles in fractionation chambers 110(n) to direct and control the rate and directional flow of biosolids 50. The weir plates 170(n) divert the biosolids 50 flow and increase the detention time that the biosolids 50 remain in fractionation chambers 110(n). As the time during which biosolids 50 are subject to FF increases, the greater volume of PFAS is removed from biosolids 50. In one embodiment, biosolids are subject to FF for about 20 minutes in each fractionation chamber 110(n). A person of ordinary skill will recognize that the precise time to perform FF on biosolids 50 may be more or less than 20 minutes to achieve the desired amount of PFAS removal.

(43) Referring to FIGS. 3A and 12, as the air bubbles rise to the surface of the fractionation chambers 110(n), they accumulate on top of the biosolids 50 as foam 350. Vacuum 240 removes foam 350 off the top of biosolids 50 by the inlet side of the Roots blower 90. The depth of the foam 350 and rate of removal are all controlled by someone skilled in the art of operating the system 10 using PLC 100. Fractionation chambers 110(n) are operable to allow a user to adjust the level adjustment of foam 350 in fractionation chambers 110(n) for efficient operation of vacuum 240.

(44) In some embodiments, fractionation chambers 110(n) have a vacuum hood 180. Vacuum hood 180 may have an adjustable slide gate valve 190 to regulate the amount of vacuum in fractionation chambers 110(n) to regulate the rate of foam removal. This rate of removal is important so that no more foam 350 than may be desired is removed from fractionation chambers 110(n). If too much foam 350 is removed, additional foam concentrate will be generated which reduces the efficiency of system 10.

(45) Another complication related to FF with high solid content biosolids 50 is called the insulation factor. PFAS particles exist throughout a solid particle. Even though some PFAS compounds are hydrophobic, they can remain insulated inside a solid particle and therefore stay in the biosolids 50. These inventions incorporate the use of a disintegration grinder 200 and a continuous flow self-cleaning screener 210 to remove any unwanted particles larger than a predetermined size. The self-cleaning screener 210 removes unwanted particles like trash, plastic, string, and the like, which are then disposed in a landfill. The grinder 200 then acts on the remaining biosolids 50 to reduce particle size to expose the PFAS to foam fractionation.

(46) As shown in FIGS. 22a-b, an embodiment of the invention includes at least one component to perform hydrodynamic cavitation on the biosolids, preferably before the biosolids undergo foam fractionation or dewatering. As shown in FIG. 22b, a pump 90 injects biosolids 50 to chloride generator 150. Chloride generator utilizes electrolysis to convert any salts that are in the biosolids into chlorine gas. 150 After the biosolids 50 are treated by chloride generator 150, biosolids 50 are directed into first venturi hydrodynamic cavitation chamber 220. As biosolids pass through first venturi hydrodynamic cavitation chamber 220 the venturi effect creates negative pressure bubbles that collapse and create supercritical water oxidation conditions 50 to destroy PFAS and microplastics from biosolids 50. Pipe 20 then conveys biosolids 50 to mechanical hydrodynamic cavitation chamber 230.

(47) Mechanical hydrodynamic cavitation chamber 230 acts on biosolids in a similar manner to create supercritical water oxidations conditions. Biosolids then exit mechanical hydrodynamic cavitation chamber 230. In an alternative embodiment, biosolids 50 are directed to high pressure pump 260. High pressure pump 260 increases the pressure of biosolids 50 and directs them to a second venturi hydrodynamic cavitation chamber 270. Second venturi hydrodynamic cavitation chamber 270 acts on biosolids 50 in a manner similar to first venturi hydrodynamic cavitation chamber 220 to disrupt and reduce PFAS and microplastics from biosolids 50. As shown in FIG. 22b, one embodiment of system 10 comprises third, fourth, fifth, and sixth venturi hydrodynamic cavitation chambers 272, 274, 276, 278 to further reduce PFAS and microplastics content from biosolids. In another embodiment, biosolids 50 leave mechanical hydrodynamic cavitation chamber 230 and are delivered to foam fractionation chamber as described in greater detail below. Alternatively, biosolids 50 leave mechanical hydrodynamic cavitation chamber 230 and are delivered to mechanical dewatering as described in greater detail below.

(48) FIG. 24 shows one embodiment of a venturi hydrodynamic cavitation chamber 230, 270, 272, 274, 276, 278. In one embodiment, venturi hydrodynamic cavitation chamber 220 has a diameter of about 4. Venturi hydrodynamic cavitation chamber 220 comprises a convergent section 450 and a divergent section 460. In convergent section 450, the diameter of chamber 220 restricts at a rate of about 22.5 until the diameter is about 0.75. After biosolids 50 pass through convergent section 450, they enter divergent section 460. In the divergent section 460 the diameter increases from about 0.75 at a rate of about 7 until it again reaches 4.

(49) Hydrodynamic cavitation is the process of bubble formation, expansion and violent collapse which results in the generation of high pressures up to about 1600 bar and temperatures up to about 4600 Kelvin for a fraction of a seconds. Cavitation occurs if the local pressure declines to some point below the saturated vapor pressure of the liquid and subsequent recovery above the vapor pressure. In pipe systems, cavitation typically occurs either as the result of an increase in the kinetic energy (through an area constriction) or an increase in the pipe elevation. Hydrodynamic cavitation can be produced by passing a liquid through a constricted channel at a specific flow velocity or by mechanical rotation of an object through a liquid. In the case of the constricted channel and based on the geometry of the system, the combination of pressure and kinetic energy can create the hydrodynamic cavitation cavern downstream of the local constriction generating high energy cavitation bubbles. In a closed fluidic system, a decrease in cross-sectional area leads to velocity increment and static pressure drop. In one embodiment, the grinder 200 and self-cleaning screener 210 remove any particles larger than about 2 mm in diameter. Other embodiments may use grinders 200 and screeners 210 to remove particles exceeding a predetermined threshold that may be smaller or larger than 2 mm in diameter. This screening, combined with violent aeration, intense mixing through a static mixer, and repeating movement in the fractionation chambers 110(n), reduce the size of biosolids 50 to fine particles. This process is unique in that it breaks opens the biosolid 50 particles and allows for the release of hydrophobic PFAS compounds that are inside biosolids 50.

(50) Referring to FIG. 22, in one embodiment, hydrodynamic cavitation is used to reduce the size of biosolids 50 particles thereby creating greater overall surface area of biosolids 50. Hydrodynamic cavitation refers to the process of cavitation bubble formation, growth, and collapse in the liquid when the local pressure of the fluid is lower than the saturated vapor pressure.

(51) Referring to FIG. 1-6, once the biosolids 50 have been diluted to about 1% solids and reduced to particles smaller than about 2 mm, a surfactant may be added to aid in the formation of bubbles. Surfactants aid in the formation of bubbles and dosage will vary from product to product. Injection of the surfactant is through the use of a positive displacement rotary lobe pump 360. In one embodiment, the rotary lobe pump 360 is a Vogelsang pump. The surfactant is injected into an injection ring through four injection ports around the pipe 20 for even distribution. Once injected, the combination of biosolids 50 and surfactant is mixed by static mixer 60. The static mixer 60 may be positioned in line with pipe 20 before biosolids 50 are introduced to chambers 110, 115, 120, 125, 130.

(52) Even though some PFAS compounds are hydrophobic, they can remain trapped inside the biosolids 50 unless there is a mechanism to remove PFAS particles from the biosolids 50. Foam Fractionation does that by creating air bubbles in the biosolids 50. The hydrophobic PFAS compounds attach themselves to the bubbles and rise to the top of fractionation chambers 110(n), essentially positioned as a layer on top of the biosolids.

(53) A vacuum 160 then removes the PFAS particles and microplastics from first fractionation chamber 110 and delivers them to second fraction chamber 115. Once the foam 350 has been vacuumed off the top of the first chamber 110, the foam 350 goes through a demister 80 which substantially breaks the bubbles and converts them into water and concentrated PFAS. The velocity slowing chamber 70 retards the speed of air/foam that is recovered from fractionation chambers 110(n) and bursts the bubbles in the foam, thereby concentrating the foam before vacuum 240 removes the foam from fractionation chambers 110(n). The velocity slowing chamber 70 slows the velocity of biosolids 50 to less than about 30 ft/min. A demisting pad 80 eliminates liquid vapors and pass through a dryer air supply to the vacuum side of the blower. Demisting pads 80 are made in various sizes and shapes and are commonly available.

(54) This concentrate accumulates in second fractionation chamber 115 and the process described above in the context of the first fractionation chamber 110 repeats. This process is then repeated so that foam 350 containing PFAS is vacuumed from second fractionation chamber 115 and delivered to third fractionation chamber 120. The process may be repeated as desired to remove PFAS. In one embodiment, the process uses five fractionation chambers 110(n). At each fractionation chamber 110(n), the concentration of PFAS in foam 350 increases. As the number of cycles of FF increases, the more concentrated the foam 350 becomes, thereby reducing the resulting volume of foam 350 to be discarded.

(55) Some biosolids 50 may not have the requirement for adding surfactant 355, however in most applications, a higher PFAS and microplastics removal rate is achieved when surfactants are added. Various commercially available options exist for surfactants. One skilled in the trade will be able to try different types for the best performance. In one embodiment, Decyl Glucoside or Nonylphenol Ethoxylated are used to help aid in the formation of bubbles. However, many different types of surfactants can be used.

(56) The success of PFAS and microplastic removal depends on various factors. One of which is the amount of time that the biosolids 50 remain in fractionation chambers 110(n). The longer the fractionation process continues, the greater the amount of PFAS is removed from biosolids 50 and encapsulated in foam 350. In one embodiment, biosolids remain in fractionation chambers 110(n) for about 20 minutes. This invention deploys weirs 170(a-n) within chambers 110, 115, 120, 125, 130 to permit a full 20 minute treatment process and protects against short circuiting. The weirs 170(n) force the material to flow around the weirs 170(n) and not flow in a straight line from entry to exit. This increases the dwell time in the chambers 110(n) to make sure the material remains in chambers 110(n) about 20 minutes. Otherwise, material could come in and go straight to the outlet in a few minutes and not have enough time for adequate treatment. In one embodiment, FF for more than 20 minutes has diminished benefits and cost effectiveness.

(57) Once the biosolids 50 have been processed through fractionation chambers 110(n) the system 10 transports biosolids 50 to a dewatering device 250 to reduce volume by removing water before disposal. In one embodiment, the dewatering device 250 is a centrifuge or belt press. In another embodiment, the dewatering device is a mechanical press device as described in published application US 2023/0174403 A1, which is incorporated herein by reference in its entirety. After dewatering, the biosolids 50 can be processed through a Double Drum Drying process as described in published application US 2022/0315500 A1, which is incorporated herein by reference in its entirety. In this combination, wastewater treatment plant generators would not need to have any digesters potentially saving millions of dollars in capital and operating costs.

(58) During each subsequent stage of foam fractionation processing, any liquid that is not removed as foam is returned to the stage one foam fractionation chamber 110 for further processing to achieve acceptable levels of PFAS.

(59) Once complete, the PFAS and microplastics containing foam 350 may be disposed. Volume reduction ranges for each fractionation stage is 10-30%. The concentrate will contain PFAS and microplastics removed from biosolids.

(60) A unique part of this invention is the development of combining pressure transducers 430 at the bottom of fractionation chambers 110(n). The pressure transducers 430 identify volume of biosolids 50 in fractionation chambers 110(n). In one embodiment, the volume of biosolids is determined by measuring the height of biosolids 50 relative to the height of fractionation chambers 110(n). Through the PLC communication portal 280, the transducers 430 transmit a signal to the electronic drain valves 420 at the bottom of fractionation chambers 110(n). The drain valves 420 are opened and closed according to the volume of biosolids 50 in the chambers 110, 115, 120, 125, 130 to ensure the tanks continuously remain full of biosolids. This mechanism also allows the operator to control the height of the foam 350 in the vacuum hood 180.

(61) The control signal is then communicated to the original biosolids pump 35 that pumps biosolids 50 to the first stage chamber 110. Depending on the volume of biosolids in fractionation chambers 110(n), the biosolids pump 35 is automatically adjusted to maintain the desired volume of biosolids 50 in fractionation chambers 110(n). The continuous monitoring of biosolids 50 volume in fractionation chambers 110(n) allows the foam fractionation method and system to run continuously and autonomously.

(62) When the PFAS concentrated foam 350 is removed from fractionation chambers 110(n), it may be optionally processed through a supercritical water oxidation process (i.e., SCWO) SCWO uses high pressure and high temperature to oxidize substantially all organics and PFAS compounds with up to a 99% removal rate. Alternately, other disposal methods may be used depending on operator preference and available technologies in the area. Alternatively, the PFAS concentrated foam 350 may be dried to reduce the volume to be disposed.

(63) Applying the system and methods as described can result in one plant that produces 200,000 gallons of biosolids per day could reduce that volume to less than 10-200 gallons of highly concentrated PFAS and microplastics for disposal.