Systems And Methods For Pollutant Removal From Fluids With Pelletized High Strength Carbon Products With Reactive Binders

Abstract

A sorbent composition for pelletized carbon products having high strength and water resistance is disclosed. The invention also includes a method of producing sorbent compositions of pelletized carbon products having high adsorption capacities of phosphate and nitrates including the use of a metal oxide as a binder. The invention further includes a system for removing nutrients from a pollutant stream.

Claims

1. A pelletized carbon composition, comprising: a carbonaceous material; a metal oxide; and wherein the metal oxide is a reactive binder yielding high mechanical strength for said composition.

2. The pelletized carbon composition, according to claim 1, wherein: the metal oxide includes MgO.

3. The pelletized carbon composition, as claimed in claim 1, wherein: said carbonaceous material includes powdered or granular biochar.

4. The composition, as claimed in claim 1, wherein: said metal oxide is reactive with pollutants including at least one of phosphate and nitrate.

5. The pelletized carbon composition, as claimed in claim 1, wherein: a sorbent to mixed metal oxide ratio is between about 100:1 to 1:00, preferably lower than 10:1 and more preferably lower than 2:1.

6. The pelletized carbon composition, according to claim 1, wherein: a ratio of the carbonaceous material to the metal oxide is between 100:1 to 1:100.

7. The pelletized carbon composition, as claimed in claim 1, wherein: said metal oxide includes two metal binders.

8. The pelletized carbon composition, as claimed in claim 8, wherein: at least one of said two metal binders function for binding and complexation of nutrients.

9. The pelletized carbon composition, as claimed in claim 1, wherein: pellets of said pelletized carbon composition are dried to below 2% moisture and said pellets have a Ball Pan Hardness (BPH) of activated carbon above 95%.

10. The pelletized carbon composition, as claimed in claim 9, wherein: pellets of said pelletized carbon composition maintain their mechanical strength even when submerged in a fluid for pollutant removal applications.

11. The pelletized carbon composition, as claimed in claim 9, wherein: pellets of said pelletized carbon compositions attain the required mechanical strength (BPH) without requiring high temperature treatment or specialty chemicals.

12. The pelletized carbon composition, as claimed in claim 1, wherein: the metal oxide is a reactive binder capable of pollutant removal from fluids without requiring high temperature treatment to attain reactivity.

13. The pelletized carbon composition, according to claim 6, wherein: the ratio is less than 10:1.

14. The pelletized carbon composition, according to claim 6, wherein: the ratio is less than 2:1.

15. The pelletized composition, according to claim 1, wherein: pellets of said pelletized carbon composition maintain their mechanical strength when submerged in a fluid for pollutant removal applications.

16. A method of making pelletized carbon compositions comprising: mixing a powdered or granular carbonaceous sorbent, a metal oxide and water; extruding the mixture into pelletized structures; and drying the pelletized structures to form pelletized carbon compositions.

17. The method of claim 16, wherein: sufficient water is added to plasticize the mixture.

18. The method of claim 16, wherein: the water is a solution of water with pH modifier.

19. The method, according to claim 16, wherein: the metal oxide includes MgO.

20. The method, according to claim 16, wherein: the metal oxide includes MgO and AlO.

21. The method, according to claim 16, wherein: a ratio of the carbonaceous sorbent to the metal oxide is between 100:1 to 1:100.

22. The method, according to claim 21, wherein: the ratio is less than 10:1.

23. The method, according to claim 21, wherein: the ratio is less than 2:1.

24. A method of producing pelletized carbon products comprising: providing a composition of carbonaceous material and a metal oxide; providing an extrusion device with a selected die size and cutter speed; adding sufficient water to plasticize the mixture; feeding the composition through the die of the extrusion device to create pellets of a desired diameter and length; and wherein the metal oxide is a reactive binder yielding high mechanical strength for said composition.

25. The method, according to claim 24, wherein: said carbonaceous material includes powdered or granular biochar.

26. The method, according to claim 24, wherein: said metal oxide includes MgO.

27. The method, according to claim 24, wherein: said metal oxide is reactive with pollutants including at least one of phosphate and nitrate.

28. The method, according to claim 24, wherein: a sorbent to mixed metal oxide ratio is between about 100:1 to 1:00, preferably lower than 10:1 and more preferably lower than 2:1.

29. The method, according to claim 24, wherein: said metal oxide includes two metal binders.

30. The method, according to claim 29, wherein: at least one of said two metal binders functions for binding and complexation of nutrients.

31. The method, according to claim 24, wherein: pellets of said pelletized carbon composition are dried to below 2% moisture and said pellets have a Ball Pan Hardness (BPH) of Activated Carbon above 95%.

32. A system for removing nutrients from a pollutant stream, said nutrients at least including nitrates or phosphorous, the system comprising: a waste fluid stream containing pollutants; a reactor unit that receives a quantity of a pelletized carbon composition, the pelletized composition comprising a carbonaceous material, a metal oxide, wherein the metal oxide is a reactive binder yielding high mechanical strength for said composition; and wherein the waste fluid stream flows through said reactor unit in which adequate contact is made between the waste fluid stream and the pelletized carbon composition for removing the nutrients.

33. The system, according to claim 32, further comprising: a filtration unit located downstream of said reactor unit to receive fluid of the waste fluid stream that was treated within the reactor unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a graph illustrating removal of nutrients by MgO-biochar;

[0030] FIG. 2 is graph illustrating pollutant removal according to the invention with respect to influent & effluent concentrations of total phosphorous in the presence of a pelletized biochar with a 2.3:1 sorbent to mixed oxide ratio; and

[0031] FIG. 3 is a simplified schematic diagram depicting a system of the invention for controlling pollutants from a waste or pollutant stream.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Embodiments of the present invention are distinguishable over the conventional prior art because the prior art focuses on the use of metal salts and subsequent conversion through high temperature heating to form metal oxides as active components of carbon products. The prior art does not disclose use of metal oxides that function to bind activated carbon particles together.

[0033] In connection with embodiments of the present invention, metal oxides can be used as binders to produce pelletized carbon products with high mechanical strength and water resistance properties. The use of these metal binders has multiple functions in the pelletized carbon products. Firstly, they serve as the primary binder system to maintain the structure and shape of the pelletized carbon products. Secondly, they serve as a catalyst/active component of the pelletized carbon products for pollutant removal from fluids. In this respect, the dual function of metal oxides in pelletized carbon products has not been explored in the prior art.

[0034] Further in connection with embodiments of the present invention, water resistant and high strength carbon products can be made with manufacturing methods that do not require high temperature treatments or complex chemical processes. Furthermore, in embodiments of the present invention, it was revealed that pelletized carbon products made with metal oxide binders can be used for high temperature applications while still maintaining their high mechanical strength and water resistance.

[0035] According to the invention in the examples that follow, pelletized carbon products cylindrical in shape with 4 mm diameter and 4 mm length were extruded with a full-scale extruder. Dry components were mixed together with sufficient water to plasticize the mixture as it was fed through the extruder. Extruded pellets were dried to below 2% moisture at 150° C. Pellet hardness of the finished pelletized carbon composition was determined using the ASTM D3802 for Ball Pan Hardness (BPH) of Activated Carbon to be above 95%.

EXAMPLE 1

[0036] Pelletized carbon products were produced per the material compositions in Table 1. The binder composition of the present invention (2:1 up to 8:1 sorbent (SB) to Metal oxide (XO) ratio) shows that sufficient mechanical hardness can be attained using a metal oxide as a binder and without requiring high temperature treatment or specialty chemicals.

[0037] In this example the sorbent was dry and powdered biochar and the metal oxide was 93% purity magnesium oxide in its powdered form.

TABLE-US-00001 TABLE 1 Pilot scale production of pelletized biochar and magnesium oxide (single binder) Ratio of Ball Pan Hardness Density Particle Size SB:XO (%) (g/mL) (Diameter) 2.0 99 0.62 4 mm 3.6 98 0.61 4 mm 8.1 99 0.58 4 mm 2.3 88 0.55 4 mm 2.6 87 0.59 4 mm 1.0 95 0.65 4 mm 4.2 82 0.61 4 mm 2.6 93 0.63 4 mm 2.6 85 0.47 2 mm 0.6 97 0.67 4 mm 2.6 90 0.61 4 mm

EXAMPLE 2

[0038] In the example that follows, the extruded pelletized carbon was produced per the material compositions in Table 2. Sufficient surface area remains on the pellet to allow for sorption and constituent diffusion into the pellet. In addition, phosphorous removal of the resulting materials decreased with higher carbon content or lower metal oxide content thus showing the reactivity of the reactive binder for pollutant removal from fluids

TABLE-US-00002 TABLE 2 Lab Scale analysis for varying ratios of sorbent to metal oxide Average Total Phosphorous Surface Pore Pore Capacity Ratio of Area Size Volume (mg P/ SB:XO (m.sup.2/g) (Å) (cc/g) g Pellet) 2.0 225 34.00 0.19 0.96 3.6 235 34.00 0.2 0.83 8.1 255 30.00 0.19 0.45 2.3 — — — 0.82 2.6 — — — 1.83 1.0 — — — 3.06 4.2 — — — 1.22 2.6 — — — 1.09 1:0 — — — 0.13

EXAMPLE 3

[0039] In the examples that follows, the extruded pelletized carbon was produced per the material compositions in Table 3.

TABLE-US-00003 TABLE 3 Lab Scale analysis for varying purity of metal oxide Phosphorous XO Surface Ball Pan Capacity Ratio of Purity Area Hardness (mg P/g SB:XO (%) (m.sup.2/g) (%) Pellet) 2.0 93 235 99 0.96 2.0 60 216 99 0.30

[0040] In this example, the sorbent was dry and powdered biochar and the metal oxide was magnesium oxide in its powdered form with variation in purity from 93% to 60%. The lower purity magnesium oxide had a remaining composition of other metal oxides including Fe.sub.2O.sub.3, Al.sub.2O.sub.3, CaO.

[0041] The pellet retained sufficient surface area of 235 and 216 m2/g respectively and similar ball pan hardness of 99%.

[0042] The phosphorous removal, however, decreased by a factor of 3 from 0.96 mg P/g of pellet to 0.30 mg P/g of pellet.

EXAMPLE 4

[0043] In the example that follows, the extruded pelletized carbon was produced per the material compositions in Table 4 and exposed to phosphorous concentrations at a pilot program.

TABLE-US-00004 TABLE 4 Lab Scale analysis for pellet tested in the pilot program Average Total Phosphorous Surface Pore Pore Capacity Ratio of Area Size Volume (mg P/g SB:XO (m.sup.2/g) (Å) (cc/g) Pellet) 2.3 225 34 0.19 0.82

[0044] The pilot system was designed to treat reclaimed water at a rate of 0.3 gallons of water per square foot or equivalent to a desired maximum 6-hour contact time. The media depth tested in the reactor was 17 inches.

[0045] In this example the sorbent was dry and powdered biochar and the metal oxide was 93% purity magnesium oxide in its powdered form.

[0046] FIG. 2 illustrates pollutant removal according to the invention with respect to influent & effluent concentrations of total phosphorous in the presence of a pelletized biochar with a 2.3:1 sorbent to mixed oxide ratio.

[0047] The total phosphorous removal achieved was 79% to 89% and consistently below Advanced Wastewater Treatment (AWT) standards of 1 mg/L of total phosphorous.

EXAMPLE 5

[0048] In the examples that follows, the extruded pelletized carbon was produced per the material compositions in Table 5.

TABLE-US-00005 TABLE 5 Lab Scale analysis for pellets produced with powdered versus granular sorbent Surface Ball Pan Ratio of Area Density Hardness SB:XO Sorbent Type (m.sup.2/g) (g/mL) (%) 2.0 Dry - Powdered 216 0.65 99 2.0 Wet -Granular 108 0.46 96 (60% Moisture Content)

[0049] In this example the sorbent was wet granular biochar and the metal oxide was magnesium oxide with a purity of 60%.

[0050] The pellet surface area resulted in 216 m.sup.2/g for the dry raw material and 108 m.sup.2/g for the wet raw material. This makes sense because the wet raw material has about 60% water content and therefore only 40% of the material has active surface area.

EXAMPLE 6

[0051] In the examples that follow the extruded pelletized carbon products were produced for a multi-binder system per the material compositions in Table 6. The binder composition of the present invention (2.2:1 sorbent (SB) to metal oxide one (XO.sub.1); 5.5:1 SB to metal oxide 2 (XO.sub.2); and a total SB:XO ratio of 1.6:1) shows that sufficient mechanical hardness can be attained using multiple metal oxides as a binder and without requiring high temperature treatment or specialty chemicals.

[0052] In this example the sorbent was dry and powdered biochar and the metal oxides were: XO1-93% purity magnesium oxide in its powdered form and XO.sub.2—iron (III) oxide, and iron oxide hydroxide, respectively.

TABLE-US-00006 TABLE 6 Pilot scale production of pelletized biochar and magnesium oxide (multiple binders) Phosphorous Ball Pan Capacity Ratio of Ratio of Ratio of Density Hardness (mg P/ SB:XO.sub.1 SB:XO.sub.2 SB:XO.sub.TOTAL (g/mL) (%) g Pellet) 2.2 5.5 1.6 0.64 94 1.27 2.2 5.5 1.6 0.63 97 1.43

[0053] Referring now to FIG. 3, a simplified system 10 is illustrated for controlling pollutants from a waste fluid stream. This figure is intended to represent a simplified system, it being understood that additional processing may be added to this system in order to effectively treat a waste fluid stream. A waste fluid stream 12 enters a reactor unit 16 that is used to treat the fluid stream. At some point upstream of the reactor unit 16, the pelletized carbon composition 14 of the invention is introduced into the waste fluid stream 12.

[0054] It should be understood that depending upon the specific design of the reactor unit 16, the carbon composition can be added at concentrations or amounts appropriate to treat the contamination in the fluid stream. Therefore, greater or lesser amounts of the pelletized carbon can be used for optimal treatment within a particular reactor unit.

[0055] The specific manner in which the carbon composition is added to the waste stream may include any suitable means in which the carbon composition is adequately exposed to the waste fluid stream for absorption of contaminants. For example, the carbon composition may be added by exposing that composition through a torturous path of the waste stream, direct mixing, or combinations thereof.

[0056] The reactor unit itself may achieve adequate contact with the carbon composition of the invention by any one of selected modifications of the fluid stream flow such as providing adequate fluid turbulence, torturous path flow of the fluid under pressure, mechanical or vibratory mixing of the fluid stream, and others. The specific parameters for mixing and exposure times within the reactor can be determined based upon the particular chemical characteristics of the waste stream.

[0057] After treatment of the waste fluid stream 12 within the reactor 16, the waste fluid stream may be further treated, such as by a downstream filtration unit 18 in which a final separation is achieved between a treated fluid stream 20 and captured pollutants 22. The downstream filtering shall be understood to be an optional treatment step.