CLARIFYING, FILTERING AND DISINFECTING PROCESSING WATER FOR REUSE

Abstract

Wastewater may be reconditioned for re-use in a food processing line. The wastewater is subjected to coarse particle separation on the wastewater to create first stage water, after which large and small particles in the first stage water are separated in a liquid waste separator to create a second stage water. The second stage water is directed to a flocculation settling tank to aggregate remaining solids, and the remaining solids are removed to create a third stage water. Finally, the third stage water is treated with at least one of UV light and chemical antimicrobials to create reusable water. The reusable water is delivered upstream to reduce fresh water requirements. Ferrate (IV) is an exemplary antimicrobial that has broad applications in the food processing line.

Claims

1. A method of treating and reusing wastewater for food processing, the method comprising: (a) conducting a coarse particle separation on the wastewater to create first stage water; (b) separating large and small particles in the first stage water in a liquid waste separator to create a second stage water; (c) directing the second stage water to a flocculation settling tank to aggregate remaining solids, and removing the remaining solids to create a third stage water; and (d) treating the third stage water with at least one of UV light and chemical antimicrobials to create reusable water.

2. A method according to claim 1, wherein step (a) is practiced by trammel screening and floatation.

3. A method according to claim 1, wherein step (b) is practiced using a series of the liquid waste separators.

4. A method according to claim 3, wherein step (b) is practiced with the series of the liquid waste separators using progression in a ratio of centripetal force to fluid resistance.

5. A method according to claim 1, wherein step (c) is practiced using ferric chloride, wherein the remaining solids either precipitate to a bottom of the flocculation settling tank or float to surface for removal by a skimmer.

6. A method according to claim 1, wherein step (d) is practiced using a centrifugal pump to recirculate the third stage water into a disinfecting tank for treatment.

7. A method according to claim 1, wherein after step (d), the reusable water is directed to at least one of a chill tank, a post-chill tank, and a scalding tank.

8. A method according to claim 7, wherein step (d) is practiced using peracetic acid in a concentration of 50 ppm.

9. A method according to claim 1, wherein step (c) comprises using Ferrate (Fe(VI)) to flocculate the remaining solids and to disinfect the second stage water.

10. A method according to claim 1, wherein step (d) is practiced using Fe(VI).

11. A method of processing poultry and of treating and reusing wastewater from poultry processing, the method comprising: (a) immersing the poultry in a scald tank; (b) removing feathers of the poultry in a picker; (c) cleaning and processing the poultry; (d) immersing the poultry in a chill tank; and (e) further processing the poultry for packaging, wherein wastewater from at least one of steps (a), (c), (d) and (e) is treated by: (i) conducting a coarse particle separation on the wastewater to create first stage water, (ii) separating large and small particles in the first stage water in a liquid waste separator to create a second stage water, (iii) directing the second stage water to a flocculation settling tank to aggregate remaining solids, and removing the remaining solids to create a third stage water, and (iv) treating the third stage water with at least one of UV light and chemical antimicrobials to create reusable water, and wherein the reusable water is recirculated for use in at least one of steps (a), (c), (d) and (e).

12. A method according to claim 1, wherein step (iii) comprises using Ferrate (Fe(VI)) to flocculate the remaining solids and to disinfect the second stage water.

13. A method according to claim 1, wherein step (iv) is practiced using Fe(VI).

14. A method according to claim 13, wherein the Fe(VI) is mixed with the third stage water in a concentration of 500-1500 ppm.

15. A method according to claim 11, further comprising applying Fe(VI) directly to the poultry in at least one of steps (a), (c), (d) and (e).

16. A method according to claim 11, wherein steps (i)-(iv) are practiced in the liquid waste separator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and other aspects and advantages will be described in detail with reference to the accompanying drawings, in which:

[0025] FIG. 1 is a flow diagram showing the methodology for reconditioning wastewater; and

[0026] FIG. 2 is a system and process diagram showing an exemplary application for reconditioned wastewater.

DETAILED DESCRIPTION

[0027] Water runoff can be captured at various stages of a food processing line. The systems and methods of the described embodiments recondition the runoff wastewater, and the reconditioned water is suitable for use in upstream processes. The systems and methods will be described in the context of poultry processing, but the methodology of the invention is readily suitable to other types of food processing such as swine, beef, seafood, and fresh produce.

[0028] Wastewater runoff generally contains organic material comprised of two separate components: (1) large lumps of fat and grease, and (2) emulsified globules. Treatment and removal is performed in two distinct processes. With reference to FIG. 1, the wastewater is initially processed via an initial coarse particle separation using a trommel screen (step S1) to create a first stage water. Particles which remain in suspension will be carried to an intervention, which includes a series of self-cleaning hydrocyclone clarifiers designed to separate both large and small particles using a progression in the ratio of centripetal force to fluid resistance to create a second stage water (step S2). Hydrocyclone clarifiers will run in series continuously yet could run independently when a single unit must be taken offline for maintenance.

[0029] After the wastewater stream is processed by the hydrocyclone clarifiers to create the second stage water, the second stage water will be carried to a flocculation settling tank with skimmers (step S3) to create a third stage water. Economical flocculants such as ferric chloride could be employed during this step to aggregate remaining solids and either precipitate to the conical bottom where they will be removed and sent back to the hydrocyclone clarifier, or float to the surface where they will be removed via skimmer and sent back to the hydrocyclone for reprocessing.

[0030] Flocculation tank overflow of the third stage water would then be sent to the final filtration intervention, which involves the use of a centrifugal pump to recirculate water into a disinfecting tank where it will be treated with UV light and existing chemical antimicrobials such as PAA or free chlorine or the like to create reconditioned of reusable water (step S4). The reconditioned water would then become potable and could be reused for processing within the USDA guidelines described in 9 CFR 416.2 (g)(3) (step S5).

[0031] Ferrate(VI) chemistry is currently an active area of research. The chemistry of oxo complexes of iron has demonstrated remarkable applications of Ferrate(VI) as a highly potent bacteriocide and environmentally friendly oxidant for destruction and removal of organic and inorganic toxins. The intriguing reaction pathways of self-decay of highly oxidized iron has no known parallel for the observed phenomenon of the formation of molecular oxygen by oxidation of water. It is reported that the high level of ionization energy (556 eV) for the (FeO.sub.4).sup.2 anion cannot be compensated by the ionic and covalent binding energies with the four O.sub.2 ligands. More research is required to determine reliable models for molecular and electronic structure of Ferrate oxidation states and condensation reactions before Ferrate(VI) disinfection activity can be understood completely.

[0032] Disinfection, Chemical Oxidation and Coagulation are critical processes in water treatment that can all be achieved with the use of Ferrate(VI). In aqueous solutions, Ferrate(VI) disinfects by releasing reactive oxygen and OH radicals that kill organisms harmful to human health such as bacteria and viruses. The reduction pathway of Ferrate(VI) to Fe(III) drives chemical oxidation of both organic (lipids, proteins, humates, bacteria) compounds and eliminates odors by oxidizing organic and inorganic compounds (Acetic Acid and sulfur and nitrogen). Reduced Ferrate(III) hydroxide reacts with non-settling suspended particles so that they hydrate and attach to each other. Adsorbed fats and proteins form colloidal particles that can be removed by clarification/filtration processes. Treated wastewater can then be recycled, displacing some of the fresh makeup water in the initial wash operation.

[0033] In aqueous solutions, the Ferrate(VI) condensation pathway leads to reduced forms Fe(III) hydroxide and Fe(II) oxide. The majority of the decay reactions lead to hydrogen peroxide and gaseous oxygen along with hydroxyl anion from both reduced Ferrate(III) and dissociated water. It is proposed that these anions act simultaneously in wastewater treatment/purification systems to effect oxidation of inorganic and organic matter, destroy cellular membranes, and adsorb/coagulate solids. There are no harmful by-products from Ferrate(VI) applications, and it is therefore considered a green environmentally friendly chemical.

[0034] EPA has approved the use of Ferrate(VI) for disinfection and clarification of potable municipal wastewater systems. Chemical inputs (Ferric chloride, Sodium hypochlorite, and sodium hydroxide) are currently approved for use in municipal treatment facilities. Ferrate chemical reaction products are non-toxic products: sodium Ferrate(VI), sodium chloride (salt) and water. Ferrate(VI) degradation products of Ferric chloride and Ferric(III) hydroxide adsorb/coagulate and precipitate solids, including killed pathogens, are non-toxic and can be disposed of as filtered sediments. Moreover, in contrast with PAA, Ferrate has no inherent smell or fumes, and a benefit for processing plants will be the ability to use Ferrate (potentially at very high concentrations) at various critical control points proximal to workers without resulting in a hazardous work environment.

[0035] The oxidation-reduction capacity of Ferrate(VI) has been shown to be superior to all other commercial chemical oxidizers and disinfectants used in water and wastewater treatment. When Ferrate(VI) salts dissolve in water, the release of oxygen and formation of its reduced form Fe(III) as iron hydroxide, simultaneously disinfect, oxidize, and coagulate dissolved solids.

[0036] The term Ferrate is normally used to refer to Ferrate(VI) six valence iron (IUPAC name Ferrate(VI) or Tetraoxyironbis(olate)) although it can be used to refer to other iron containing anions salts. The most common Ferrate(VI) salt is sodium or potassium Ferrate (FeO.sub.4).sup.2. Ferrate salts can be synthesized (1) by the wet method reacting tri-valent iron in an aqueous medium under strong alkalizing conditions, (2) in the solid state by heating a mixture of iron filings and powdered potassium nitrate, and (3) by electro-chemical ionization using an iron/platinum cathode/anode connected to an electrical current source placed in a caustic electrolyte solution.

[0037] The most practical form of Ferrate(VI) currently used in wastewater treatment is sodium Ferrate salt. It is a water soluble form of Ferrate(VI) that can be produced as a high purity concentrate.

[0038] Ferrate(VI) can be produced from relatively inexpensive commercial chemicalstrivalent Ferric Chloride (FeCl.sub.3), sodium hypochlorite (NaOCl) and sodium hydroxide (NaOH). Reactant products are: Sodium Ferrate (Na.sub.2FeO.sub.4), Sodium Chloride Salt (NaCl), Ferric Hydrate (Fe(OH).sub.3) and water.

[0039] It has been shown that Ferrate(VI) is a powerful chemical technology for disinfection, chemical oxidation, and coagulation of waste-water treatment systems. It is proposed that use of Ferrate(VI) in a Poultry Waste-Water system has the following advantages/disadvantages over current chemical treatment technologies:

TABLE-US-00001 Oxidant and Disinfection Advantages Disadvantages Ferrate(VI) (i) Excessive capacity of (i) Low Ferrate(VI) Oxidation; production rate; (ii) non-toxic byproducts; (ii) lack of stability for (iii) ability of colloidal long term storage. particles coagulation; (iv) ability for long term storage disinfection, oxidation, and coagulation simultaneously; (v) needing smaller wastewater treatment plant; (vi) low application cost; and (vii) ability of inorganic and heavy metal removal. Fe(III) (i) Low residue after (i) Producing non-soluble coagulation process; solids in water; and (ii) high efficiency for (ii) alkaline compounds colloidal particles removal; usually added for better (iii) effective on pHs from performance. 4 to 6 and 6.6 to 9.2; and (iv) low cost.

[0040] FIG. 2 is an exemplary system diagram showing the use of reconditioned wastewater in a poultry processing system. Generally, after slaughtering, the birds are immersed in a scald tank 12, which serves to help loosen feathers. Feather removal is performed in a picker 14, and the birds are rehung for evisceration 16. In various processing stages 18, the birds are further cleaned and sprayed with disinfectant and the like. Subsequently, the birds are immersed in a chill tank 20, and the birds are then further processed for packaging 22. Exemplary water usage at each phase is shown in FIG. 2.

[0041] FIG. 2 shows a plurality of liquid waste separators 24 that are positioned at various stages in the line. Each of the liquid waste separators 24 receives wastewater from one or more of the noted processes and performs the noted steps S1-S5 from FIG. 1. At least steps S3 and S4 may utilize Ferrate(VI) to both flocculate solids and disinfect the water. The liquid waste separators 24 are placed at different points in the processing plant to create a side-stream of water that is cleaned up and used backwards somewhere in the processing.

[0042] In some embodiments, Ferrate(VI) is incorporated into the existing processing line using high-pressure nozzles spraying directly onto carcasses pre- and post-evisceration. A direct application of Ferrate is also potentially applicable in the chill tank 20 and/or the post-chill processing 22 for cut-up parts or whole carcasses. Existing systems utilize cold water with high levels of chemicals like PAA to chill the carcass and provide final disinfection prior to packaging. High levels of PAA, however, are detrimental to the final product by removing fat from the carcass, reducing yield and adding organic matter to the wastewater. Ferrate is more stable at lower temperatures than high temperatures and will not result in fat being separated from the carcass.

[0043] The Ferrate process of the described embodiments was developed from an extensive literature search of scientific papers on Ferrate chemistry and practical applications to commercial production. Development of the process considered use of many iron based starting materials and oxidants to drive the reaction, as well as pH and pKa considerations for Ferrate product stability. More development of the process chemistry is planned to improve commercial production and application of Ferrates in food disinfection applications. For example, Ozone may act as another (more expensive) oxidant to push further conversion of Fe3+ to Fe6+.

[0044] The described system is designed to be implemented alongside existing processing equipment without the need for excess fabrication or disruption of standard processing practices. Because of the cost-effective nature of the system, redundant equipment will be implemented at each step to allow for continuous online processing even when a single piece of equipment must be isolated and taken offline for cleaning, maintenance, or replacement.

[0045] In addition to cleansing water for reuse within the chill, post-chill or scalding tank, an additional use for the reconditioned wastewater could be to increase the amount of pressure and volume of water that is used to cleanse the carcass or product during washing, rinsing, scalding, feather or hair removal, evisceration, transportation along belts/ramps, chilling, and post-chilling. Additionally, this reconditioned water could be used to clean equipment or the facility itself within the guidelines of 9 CFR 416.2 (g)(3) to reduce the overall likelihood of cross-contamination.

[0046] An additional benefit of the invention is that it enhances the natural disinfecting power of commonly used chemicals. For example, poultry processors currently use upwards of 1200 ppm of PAA in the chill tank to reduce microbes because the efficacy is greatly decreased by the large organic load. However, with a lower level of organic material present in the wastewater, PAA is effective at 50 ppm. This invention would allow processors to use less chemicals while still achieving the same or even enhanced antimicrobial activity. Not only would this save money on the chemicals themselves, but it also decreases the chances of any occupational health hazards for employees who encounter the chemicals daily.

[0047] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.