Method and apparatus for treatment of an animal processing wastewater stream

Abstract

The present invention relates to the treatment of a wastewater stream that is generated from animal processing such as the processing of chicken, beef or pork. More particularly, the present invention relates to the separation of usable protein from an animal processing wastewater stream using a density modifier and a modification of the protein phase density to enhance lipid fat phase separation from protein solids.

Claims

1. A method of treating an animal processing wastewater stream which includes lipids and protein solids, the method comprising: a) providing a first stage that acidifies the wastewater stream, wherein the wastewater stream pH is adjusted to a value in the range of 4.8-5.2; b) adding a density modifier to the wastewater stream, said density modifier including lanthanum, cerium, or praseodymium salts or a combination thereof at a dosage rate in the range of 10-1000 milligrams per liter; c) adding a cationic polymer to the wastewater stream; d) adding an anionic polymer to the wastewater stream; and e) separating density modified floating material that includes protein solids from the wastewater stream with one or more dissolved air flotation units.

2. The method of claim 1 wherein a second stage includes transmitting the wastewater stream to a holding tank.

3. The method of claim 1 wherein in b the density modifier includes lanthanum salt.

4. The method of claim 1 wherein in b the density modifier includes cerium salt.

5. The method of claim 1 wherein in b the density modifier includes praseodymium salt.

6. The method of claim 1 wherein in b the dosage rate is between in the range of 80-240 milligrams per liter.

7. The method of claim 2 wherein the second stage includes holding the wastewater stream in the holding tank for 1-4 hours.

8. The method of claim 7 wherein the wastewater stream is held in the tank for 2-4 hours.

9. The method of claim 2 further comprising discharging the wastewater stream from the holding tank to a chemical injection treatment that injects a further density modifier.

10. The method of claim 1, wherein the material that is separated is further separated into fat and protein.

11. A method of treating an animal processing wastewater stream including lipids and protein solids, the method comprising: a) acidifying the wastewater stream, wherein the wastewater stream pH is adjusted to a value of in the range of 4.8-5.2; b) adding a first density modifier to the wastewater stream, said density modifier including one or more of lanthanum, cerium, or praseodymium salts; c) adding a cationic polymer to the wastewater stream; d) adding an anionic polymer to the wastewater stream; e) after d separating density modified floating material that includes protein solids from the wastewater stream with a dissolved air flotation unit; f) holding a volume of the wastewater stream in a holding tank for a time period of between 1 and 12 hours; g) discharging the volume of f from the holding tank; h) treating the volume discharged in g) with a second density modifier; and i) using a second dissolved air floatation unit to remove material that includes protein solids from the wastewater stream after h.

12. The method of claim 11 wherein the first density modifier and the second density modifier include lanthanum salt.

13. The method of claim 11 wherein the first density modifier and the second density modifier include cerium salt.

14. The method of claim 11 wherein the first density modifier and the second density modifier include praseodymium salt.

15. The method of claim 11 wherein in b the dosage rate is in the range of 80-240 milligrams per liter.

16. The method of claim 11 wherein the wastewater flows in a continuous stream between a and e.

17. The method of claim 11 wherein the polymers of c and d are dosed at a rate of between 5 and 50 milligrams per liter of wastewater.

18. The method of claim 11 wherein the wastewater has an initial biological oxygen demand (B.O.D.) in the range of 1800-3000 milligrams per liter.

19. The method of claim 11 the wastewater has a biological oxygen demand (B.O.D.) in the range of 500-1000 milligrams per liter after e.

20. The method of claim 11, wherein the material that is separated is further separated into fat and protein.

21. The method of claim 20, wherein the material that is separated is dissolved air flotation float.

22. A method of treating an animal processing wastewater stream including lipids and protein solids, the method comprising: acidifying the wastewater stream to a pH value in the range of 4.8-5.2; adding a density modifier to the wastewater stream, said density modifier including one or more of lanthanum, cerium, or praseodymium salts; adding a cationic polymer to the wastewater stream; adding an anionic polymer to the wastewater stream; and separating density modified floating material that includes protein solids from the wastewater stream.

23. The method of claim 22, wherein the material that is separated is further separated into fat and protein.

24. The method of claim 23, wherein the material that is separated is dissolved air flotation float.

25. The method of claim 22, wherein the material that is separated is dissolved air flotation float.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:

(2) FIG. 1 is a diagram of a preferred embodiment of the apparatus of the present invention and showing the method of the present invention;

(3) FIG. 2 is a diagram of a preferred embodiment of the apparatus of the present invention and showing the method of the present invention showing the extraction process; and

(4) FIG. 3 is a diagram of a preferred embodiment of the apparatus of the present invention and showing a method for mixing lanthanum and water.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIG. 1 shows a preferred embodiment of the apparatus of the present invention designated generally by the numeral 10. Wastewater treatment system 10 can include a first phase to replace ferric salts and to verify treatment efficacy. A second phase verifies yields on protein/fat. In FIG. 1, wastewater flow 11 from an animal processing plant can be for example about one thousand gallons per minute (1,000 gpm). The raw biological oxygen demand (B.O.D.) of this wastewater stream 11 can be between about 1800-2000 milligrams per liter (mg/l). The first stage treatment can include a first flocculation unit or floc tube 16. A second stage treatment can include a second floc tube 20 as part of a second chemical injection site. As part of the first stage of the method of the present invention, acid 12 (e.g., sulfuric acid, hydrochloric acid) is added to acidify wastewater stream 11, bringing pH to between 4.8 and 5.2, preferably about 5.0. A density modifier 13 is then added to wastewater stream 11, between 10 and 1000 milligrams per liter (mg/l), preferably between about eighty to two hundred forty (80-240) milligrams per liter. The density modifier 13 can be lanthanum, lanthanum salt, a lanthanum water mix, cerium, praseodymium salt or a combination of one or more of those. Arrows 34, 35, 36, 37 schematically illustrate flow of chemicals from vessels 12, 13, 14, 15 to first flocculation unit 16 via flow lines 22, 23, 24, 25. Each flow line 22, 23, 24, 25 can be equipped with a pump (30, 31, 32, 33 in FIG. 1) to assist in transmission of material in vessels 12, 13, 14, 15 to flocculation unit 16. A cationic polymer 14 can then be added to wastewater stream 11 between and 50 mg/l, preferably about 8 mg/l. An anionic polymer 15 is added preferably between about 5 and 50 mg/l and preferably about 8 mg/l. After the chemical treatment in first flocculation unit 16, the wastewater stream discharges from flocculation unit 16 to first dissolved air floatation unit 17 via flow line 47. In dissolved air floatation unit 17, protein floats to the top of the dissolved air flotation unit 17 where it can be skimmed off into a sludge hopper or other suitable vessel.

(6) This treated wastewater stream exits first dissolved air flotation unit 17 via line 48 with a pH of between about 4.8 and 5.2, preferably about 5.0. This treated waste stream has a B.O.D. of between about 500-1000 mg/l. The treated wastewater discharged from first dissolved air floatation unit 17 is pumped/transmitted via line 48 to a holding tank or reactor vessel 18 (e.g., 300,000 gallons). Treated wastewater is retained in holding tank/reactor 18 for 1 to 12 hours. In reactor vessel 18, a lanthanum promoted redox reaction occurs that produces alkalinity.

(7) The reactor 18 effluent is pumped/transmitted via flow line 46 (arrow 19) to a second phase chemical treatment which can include use of a second flocculation unit 20. The flow rate to the second flocculation unit 20 and second dissolved air flotation vessel 21 can be between 1,000 and 1,500 gallons per minute, such as about 1200 gallons per minute. In line chemical injection at second flocculation unit or floc tube 20 further reduces the B.O.D. of the wastewater stream to less than 240 mg/l. Chemical injection of sulfuric acid 12, rare earth/lanthanum mix 13, cationic polymer 14 and anionic polymer 15 are via flow lines 26, 27, 28, 29 as shown in FIG. 1. Each flow line 26, 27, 28, 29 can be supplied with a pump (38, 39, 40, 41 in FIG. 1). Arrows 42, 43, 44, 45 schematically show flow from vessels 12, 13, 14, 15 via flow lines 26, 27, 28, 29 to second flocculation unit 20.

(8) Flow line/arrow 22 designates flow of the wastewater stream from second flocculation unit 20 to second dissolved air floatation unit 21. Protein floats to the top of the second dissolved air floatation unit 21 separating from the wastewater and is skimmed off the top of the dissolved air floatation unit into a sludge hopper or selected vessel. Recovered skimmed material is now suitable for disposal or further processing such as separating the fat and protein. After the chemical treatment with the selected rare earth density modifier of second flocculation unit 20 and second dissolved air floatation unit 21 treatment, the wastewater stream is suitable for discharge via flow line 49 into, for example, a municipal water stream and is well within required regulatory parameters for safety (e.g., BOD equals 500-1,000 mg per liter).

(9) FIG. 2 shows an extraction process of the apparatus and method of the present invention. Dissolved air floatation float from the processing plant (dissolved air flotation units) is preferably dried in a vacuum rotary dryer (and then preferably baked in an oven, if necessary) until the solid content is approximately 85%.

(10) The process of separating the protein meal from the fat is as follows:

(11) The dried dissolved air floatation float is placed into an extraction vessel 50, which preferably has a heat resistant liner bag, until the bag is approximately 90% full. The vessel 50 is preferably closed using a quick-closure lid 60. Extraction vessel 50 can have a volume of 2,100 L, a temperature of 60 C., and a pressure of 70 bar, and can hold 550 gallons.

(12) At this time, a heated solvent from solvent storage tank 56 and via heater 53 is pumped with solvent pump 54 and compressor 59 into the extraction vessel 50 (for example, acetone, ethyl, laurate, hexane, and/or CO.sub.2) at a ratio of 10% solvent to 90% dissolved air floatation float.

(13) Solvent storage tank 56 can have a volume of 3,000 L and ambient temperature, and can hold 800 gallons. Solvent heater 53 can be 5 KW. Solvent pump 54 can be 10 KW. Compressor 59 can be 40 KW.

(14) The CO.sub.2 is then pumped from a CO.sub.2 storage 55 into the extraction vessel 50 until the desired pressure is attained. For example, for a 2100 liter (550 gallons) vessel, and a temperature of 60 C. (140 F.), the CO.sub.2 is pumped via pump 58 into the extraction vessel 50 until a pressure of 70 Bar (1000 psi). CO.sub.2 storage 55 can have a volume of 2,000 L, a temperature of 20 C., and a pressure of 60 bar, and can hold 500 gallons.

(15) The cycle is repeated at least one more time, or multiple times.

(16) When the desired number of cycles have been completed, the extraction vessel 50 is pressurized using the CO.sub.2, and the new separated fat is pressed out of the extraction vessel 50 through a bottom valve 61.

(17) The compound of fat, acetone and some CO.sub.2 now flows through piping 68 to a CO.sub.2 evaporator 57 (150 kilowatt for example) where the CO.sub.2 gas is sent to a CO.sub.2 condenser 52 (150 KW) and then returned in liquid form into the CO.sub.2 storage tank 55. Evaporator 57 can be 150 KW. Condenser can be 150 KW.

(18) Meanwhile, the fat/acetone (solvent) compound enters a separator 51 at a temperature of, for example 30 C. (70 F.) and a pressure of 1000 psi. Alternatively, the fat/acetone compound could be processed through a distiller (for example, 100 liter) at a temperature of 150 C. (302 F.) and a pressure of 1 Bar (14 psi).

(19) The acetone is separated in the liquid/gaseous form, and leaves the separator 51 (or distiller) and enters into the solvent storage tank 56 for the next cycle. Separator 51 can have a volume of 100 L, a temperature of 30 C., and a pressure of 70 bar.

(20) The dried protein meal bag is removed from the extraction vessel 50, the fat is removed from the separator 51 (distiller) and the next cycle begins.

(21) FIG. 3 shows a method of mixing lanthanum and water. Lanthanum is a commercially available solid crystal material. The lanthanum is placed in a hopper 67. Auger or conveyor device 62 transports the lanthanum into a mixing tank 63. Mixing tank 63 can be about 8 diameter and about 7 in height, and can hold about 2,000 gallons. Lanthanum is dissolved with water in mixing tank 63 with rotating paddles 64. Paddles 64 can be driven by motor drive 69 and drive shaft 70. The mixture of lanthanum and water is then pumped via piping 65 to holding tank 66. Holding tank/vessel 66 can be 12 diameter and 8 in height, and can hold about 7,500 gallons. Holding tank/vessel 66 can be provided with discharge pipe 71.

(22) The following is a list of parts and materials suitable for use in the present invention:

(23) TABLE-US-00001 PARTS LIST: PART NUMBER DESCRIPTION 10 treatment system 11 wastewater stream/influent pipe 12 acid/vessel 13 density modifier/vessel 14 cationic polymer/vessel 15 anionic polymer/vessel 16 flocculation unit/floc tube 17 first dissolved air flotation unit 18 reactor/vessel 19 arrow - reactor discharge 20 flocculation unit/floc tube 21 second dissolved air flotation unit 22 flow line/arrow 23 flow line/arrow 24 flow line/arrow 25 flow line/arrow 26 flow line/arrow 27 flow line/arrow 28 flow line/arrow 29 flow line/arrow 30 pump 31 pump 32 pump 33 pump 34 pump 35 pump 36 pump 37 pump 38 pump 39 pump 40 pump 41 pump 42 arrow 43 arrow 44 arrow 45 arrow 46 flow line 47 flow line 48 flow line 49 flow line 50 extraction vessel 51 separator 52 CO.sub.2 condenser 53 solvent heater 54 solvent pump 55 CO.sub.2 storage 56 solvent storage 57 CO.sub.2 evaporator 58 CO.sub.2 pump 59 compressor 60 quick closure lid 61 valve 62 auger/conveyor device 63 mixing tank 64 paddles 65 piping 66 holding tank 67 hopper 68 piping 69 motor drive 70 drive shaft 71 pipe

(24) All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. All materials used or intended to be used in a human being are biocompatible, unless indicated otherwise.

(25) The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.