WO2008124425A1

WO2008124425A1 - Process for treating waste water

Info

Publication number: WO2008124425A1
Application number: PCT/US2008/059108
Authority: WO
Inventors: Robert Goeltz; Gary Engstrom; Carl Geiling; Phillip Roberts; Dave Mitchell; Greg Parks
Original assignee: The Boc Group, Inc.
Priority date: 2007-04-04
Filing date: 2008-04-02
Publication date: 2008-10-16

Abstract

The invention is directed to processes designed to recover water used in certain aspects of the carcass processing industry and particularly the poultry processing industry. The system and treatment provided by the invention collects waste water from multiple sources and then removes solids, FOGs, animal proteins and pathogenic organisms to allow re-use of the treated water in various processing operations.

Description

PROCESS FOR TREATING WASTE WATER

FIELD OF THE INVENTION

The present invention relates generally to the field of carcass processing, and more particularly, to a water recovery, disinfection and re-use process for the processing of poultry.

BACKGROUND OF THE INVENTION

The typical carcass processing plant receives live animais from the grow-out farms, slaughters the animals, drains the blood and then removes the feathers, "paws", heads and detritus in the initial stages of processing. The carcasses are then sent to mechanized evisceration where the internal organs, digestive tract and edible and inedible parts are removed. In typical operations, some of the internal organs (i.e., heart, liver and gizzards) are harvested for food products. The carcasses are thereafter sent by way of mechanized line operations through a series of washing and sanitizing steps before the product is shipped as fresh product or packaged for freezing. These line operations typically consume large quantities of water.

Accordingly, the carcass processing industry has been characterized as a large volume consumer of water in conducting the slaughter, processing and packing of animals for both human consumption and other uses. Recent initiatives by governmental agencies have resulted in a further increase in the volume of water used to wash carcasses to meet the more stringent requirements of zero pathogen tolerance.

The carcass processing industry has been actively seeking methods of reducing the consumption of water for economic reasons. Further, limited water resources in some areas have also raised the need to reduce water consumption. The present invention provides new solutions for reducing the volume of fresh water required for processing carcasses, including poultry and other foodstuffs.

While some known systems provide for water re-use, these systems are not focused on the need to conserve water from an economic perspective and therefore faii to address critical economic restrictions inherent in carcass and other food processing operations. The present invention provides water reuse systems that are economically feasible and that provide improved savings to the food-preparing manufacturer.

In particular, known processes in the poultry processing industry have been directed at the recovery, treatment and recycle of poultry chiller bath water in a closed loop or semi-ciosed loop type of process, where water from the chiller baths is treated to remove solids, fats, oil, grease (FOG), organic compounds and microorganisms before reintroducing the treated water to the chiller baths. The main purpose behind this re-use is to reduce the electrical power needed to chill the water used in these systems. In other words, by recovering and reintroducing the already cooled chiller water back into the chiller makeup feed water, a reduction in the power needed to reduce the temperature of the incoming fresh water can be reduced. However, there are several disadvantages associated with these prior methods and systems. In particular, used chiller bath process water contains very high contamination, including organic contaminants and requires extensive treatment to enable reuse. The cost of the water treatment generally offsets any economic value gained by the energy reduction from re-use of the chiller water. Further, the prior art is limited to the recovery, treatment and re-use of the USDA required 0.5 gallon per bird overflow. The present invention avoids these disadvantages and provides new approaches and devices that are economically sensitive. There have also been a substantial number of devices designed to provide for filtering of water in carcass processing plants. Some of these devices are structurally complex requiring substantial capital expenses whiie others address different problems than water re-use. The present invention provides devices useful in water recovery, treatment and re-use processes and that solve the needs of removing gross levels of contaminants quickly, effectively and economically.

SUMMARY OF THE INVENTION

This invention is directed to processes and systems for recovery, disinfection and re-use of water used in the carcass processing industry and particularly in the poultry processing industry.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic drawing of one embodiment of the waste water re-use system according to the present invention.

Figure 2 is a schematic drawing of another embodiment of the waste water re-use system according to the present invention.

Figure 3 is a schematic drawing of a further embodiment of the waste water re-use system according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatus and methods of the present invention are described herein using the example of a poultry processing water disinfection process. However, the present invention is applicable to a wide variety of processes including, but not limited to, general carcass processing. As noted above, in the poultry processing industry, the prior art processes that include water re-use are directed to the recovery, treatment and re-use of water from the bird chiller operation. Such processes represent closed loop or semi-ciosed loop systems wherein water is collected and returned to the same point. This is inherently disadvantageous in that it limits the flexibility of the process to meet the needs of the plant operation. Further, poultry processing water in general and particularly chiller water, contains high levels of inorganics, e.g. high phosphorous levels and calcium that can precipitate as calcium phosphate or other deposits and thereby cross contaminate other poultry product or plant equipment. Moreover, closed or semi-closed loop systems experience cycling up or concentration of unwanted organic compounds such as ammonia and other organic nitrogen compounds that can have a negative impact on product contact and non-product contact applications.

The present invention overcomes the disadvantages noted above. In particular, the present invention is flexible in design and allows for collection of water for treatment and re-use from many different sources. In particular, the present invention is designed to operate in a cascade type flow where water is recovered downstream from evisceration and carcass washing operations, is treated and then re-used in upstream operations such as scalding, picking, stunning and flume type operations. Alternately, the treated water may be re-used in chiller makeup operations, sanitation wash or other approved re-use applications. This cascade type of operation provides food safety advantages by cascading the re-use water to points not used as collection points, thereby mitigating the potential for cross contamination. In addition, the cycling up and concentration of unwanted organic compounds; e.g. ammonia and organic nitrogen compounds, is avoided.

The present invention can still collect water from the chiller operation, but it is preferred that chiller water collected for In a preferred embodiment of the present invention the amount of water collected for treatment be limited to between twenty percent and forty percent of the total collected. This limitation is helps in preventing the possibility of cross contamination noted above. Similarly, once the collected water has been treated, it is preferable to limit reuse of the treated water into the chilling steps to between twenty percent and forty percent.

Sources for water collection according to the present invention include, but are not limited to, the carcass final wash stream, inside/outside carcass wash cabinets and other relatively low load source streams. Such streams are carcass specific as opposed to communal bath sources, such as the chiller bath. This makes the overall system of the present invention safer in terms of microbiological safety by avoiding a significant source of potential cross contamination. For example, the presence of one carcass containing pathogens in a communal bath creates the potential for the spread of the pathogens to other non-infected carcasses in the communal bath. In addition, the pathogenic load of process water collected from communal baths adds to the challenge of disinfection of the recovered water and raises the risk of introducing such pathogens to other processing stages when the recovered process water is re-used. As noted, the present invention overcomes these disadvantages by collecting water for re-use from non- communal bath sources.

The present invention provides significant food product safety improvements over prior art processes that re-use chiller bath water. As noted, the quality of the collected water from the sources used in the present invention; e.g. carcass final rinse and other relatively low load source streams is significantly better than the quality of the water contained in the chiller bath. This is at least in part because the final wash water does not have a long contact time with the food product and therefore does not absorb significant substantial amounts of FOGs into solution. By reusing these sources of water and avoiding re-use of chiller water and initial wash step water, the present invention significant increases food safety.

!n addition, the present invention provides significantly more favorable economic savings to plant than systems known in the prior art. This is primarily because of the use of water from sources other than the chiller bath. In particular, the chiller bath water carries a high contamination load requiring significant operational expense to clean and disinfect for re-use. The present invention avoids some of this cost, because the water source streams, e.g. final carcass wash stream, contain significantly less initial contamination mass. Because the cost of water treatment depends largely upon the mass of compounds to be removed, by significantly diluting chiller water with water from other sources or by eliminating chiller water entirely, the contaminated load on the purification process is significantly lessened as well as the treatment cost thereof.

The treatment process of the present invention is designed to deliver a final quality of water that is safe for intended use as carcass or bird chiller makeup water, evisceration wash water, inside/outside wash water, sanitation cleanup water or other use requiring a high quality, pathogen free, chlorinated wash or rinse water source. The present invention uses high volume cleaner sources of water for treatment and re-use, e.g. water collected from carcass washing in inside/outside carcass wash cabinets, water rails, organ or paw transport flumes and final rinse stages. The water treated by the system of the present invention delivers water meeting quality standards including, the absence of pathogens (e-coli, fecai coliform, aerobic bacteria, salmonella), turbidity no greater than 5 NTU's, and safe for the intended use.

Any suitable type of collection device may be used in the system of the present invention to collect the water from the identified water sources. The choice of collection device depends on the plant logistical layout and trench drain system locations as well as the elevations thereof. When the plant layout allows, it is preferred to provide custom designed collection devices to capture the source water, wherein the collection devices are located in close proximity to the water source and are connected by means of piping to a common collection header installed in the existing trench drain of the plant.

However, in plants where adequate trench drains at the appropriate elevations are not available, then the present invention provides a new recovery sump system. The recovery sump system of the present invention contributes to the process efficiency and economics and takes advantage of the physical characteristics of the waste stream to be recovered. In particular, the recovery sump system is designed to allow for a continuous overflow with a screening apparatus to remove the greatest mass of floatable solid matter and FOGs at the source. By using such a recovery sump system, the downstream mass removal is advantageously mitigated and the organic loads presented to the further stages of water treatment are reduced. This allows for more efficient oxidizer usage and the demands of liquid/solid separation are lessened.

The recovery sump devices of the present invention allows for collection of water from sources other then the chiller bath, e.g. wash or rinse cabinet(s) and are directed at the maximum recovery, treatment and re-use of such process water. In particular, the recovery sump device according to the present invention is preferably located under or adjacent to the poultry planes of wash or rinse cabinets and is situated such that the wash or rinse water, after being sprayed (using typical spray nozzles) onto the animal carcass, is captured in the main sump. This collected water contains high levels of solid materials including fat, skin, small animal parts, oils and grease as well as other organic and inorganic materials (contaminants) that have been washed off the carcass. The recovery sump device of the present invention is designed to allow this contaminant laden water to flow over and through a screened main sump top where the gross solids are captured and then continuously washed off the recovery sump device into the plant wastewater trough or piping. This washing can be further enhanced by utilizing an optimal angle of orientation. The recovered water is permitted to gravity flow over the recovery sump weirs that may be fitted with channeling devices to promote the removal of floatable contaminants. These contaminants are also removed from the device and flushed into the plant wastewater drain system.

By providing for the maximum removal of solid matter, floatable FOGs, animal parts including skin, small body parts and detritus at the source of collection, greater efficiency of the system is achieved and significant reduction of the complexity of later treatment stages is accomplished. By removing a greater mass of constituents at or close to the recovery source, the present invention significantly reduces the downstream water treatment cost.

The sump device may contain float sensors for low level and high level that are used to activate the device transfer pump. The level of water contained in the device dictates when the device is in overflow mode; e.g. the water level where water containing the floatable contaminants is higher than the sump overflow ports. The overflow ports are generally sized to allow for large pieces of material to be efficiently floated out of the system. The overflow level also ensures that the water in the device has had sufficient residence time to allow for floatation of the floatable contaminants to reach the surface of the water. When the high level sensor indicates that the overflow mode has been achieved, the transfer pump may be activated. The settings of the sensors may be calibrated during installation to allow for application specific conditions. The captured water captured flows by gravity through a series of different vertical height weirs that act as traps for solid, floatable contaminants. These weirs have flow channels in the bottom which allow for clarified water to flow. Each section of the device is designed to remove successively smaller {in mass) contaminant particles.

In a particular embodiment of the present invention related to the poultry industry, the water is collected from a poultry slaughter line wash station. A collection basin is provided for the wastewater from the carcass wash cabinets and other source points and includes a hydraulic design that allows for continuous skimming of the floatable solids and FOGs that are the typical contaminants found in such waste streams. Foilowing solids removal, the collection point also serves as a transfer point for further treatment of the water, e.g. from the processing floor to treatment systems generally located outside the processing facility.

The further treatment systems of the present invention can be provided is several stages, such as, an initial mechanical separation or screening device in combination with a common sump; a process water surge and floatation device; filtration modules; biological reactors; disinfection and oxidation modules; and a final polish module. In addition, the present invention may include a re-chlorination module and allows for automation control, on-line backup and on-line safety assurances. Each of these aspects of the present invention will be described separately below.

The water collected from the desired source points flows or is pumped to a solids separation or screening device. This device may be a self-cleaning, rotary drum screening device where solids are captured on wedge wire or other suitable media and the water is allowed to pass through the screen pours into a sump. The wedge wire mesh size may be varied to best suit the source stream. Additionally, the screening device may be configured in a double or triple drum configuration to allow for different sizes of mesh to sequentially remove solids. The screening device may be fitted with a high pressure water spraying mechanism to allow for intermittent or continuous washing of the screen mesh to prevent fouling from buildup of solids and fats. According to one embodiment of the present invention, the screening device is configured as an internal loading screen where water is passed into the center of the drum and passes through a first mesh size followed by at least one second smaller mesh size as an outer screen. This allows for different size solids to be removed in stages to prevent the fouling of the smaller mesh. The screening device is driven by a variable speed electrical motor to allow the operator to adjust the drum rotation speed for optimum performance. Varying the speed provides significant operating and performance enhancements by allowing the device to operate at the most efficient speed for the specific water source and for washing off the solids. The efficiency of the device can be further improved by using a traveling spray nozzle that is installed on a bar fitted with limit switches to define and control the distance of travel. The spray nozzle may be driven back and forth across the travel bar by way of an electric motor connected to a worm type gear or by means of water pressure. The screening device is mounted on a sump for collection of the screened water and the sump is fitted with level sensors to control the rate of flow, retention time and any designed overflow. A dedicated pump for the sump is used to transport the screened water to further treatment operations.

The process water recovered from the screening device is pumped to a floatation device designed to remove remaining floatable solids. The floatation device may employ conventional dissolved air floatation, induced air floatation or a combination of these techniques that use gas or liquid injection to promote floatation of suspended organic materials such as FOGs, fat, oil, proteins, lipids, carbohydrates and small solid particles. For example, the floatation device may be fitted with an air injection system that uses compressed air and small bubble diffusion to provide positive lift of the colloidal FOGs, undissolved animal matter and proteins present in the stream. Further, the floatation device operation may be enhanced by injection of gaseous ozone to promote flocculation of solids or may have coagulants, polymers, metal salts or other chemical agents added to enhance solids removal The floatation device also serves as a volume-balancing device for hydraulic flows through the system unit operations. In particular, the floatation device is sized to act as a volume buffer and control to accommodate the variability in source water flows and to assist the entire system in achieving the desired treatment process rate. Further, the size of the floatation device is designed to have a sufficient volume to provide for continuous operation, even in the event of interruption of influent water into the treatment system during any processing downtimes, such as worker breaks or maintenance shutdown. The floated matter is removed from the tank by an overflow and skimming device and the skimmed material may then be sent for further processing or rendering.

The water recovered from the floatation device is then treated by one or more filtration modules, depending on the filtration need. In particular, a pretreatment module may include equalization and primary treatments. The equalization process collects the influent water in an offal pit and pumps it to a high volume capacity basin, typically one or more 20,000 gallon equalization basins. Primary treatment comprises treating the water in a dissolved air flotation (DAF) unit having coagulants and flocculants added to remove solids and FOGs. The solids collected from this primary treatment may be stored and thickened in a residual storage tank and then hauled away for land applications.

The water is pumped by means of a centrifugal pump, an end suction pump, a top discharge type pump, or other suitable means, to a pre-treatment module comprising any one or more of filtration devices, vacuum or pressure type diatomaceous earth filtration vessel(s), electrocoagulation reactor(s), membrane separation modules or other comparable technologies. The media used in these vessels can be standard, commercial grade diatomaceous earth, chosen for optimal performance depending on the water source and preferably pre-coated onto a stainless steel matrix septum of the vessel. For filtration pre-treatment modules serve to further reduce organic content including FOGs and can be operated at a higher flow rate than the rest of the process to allow for multiple pass type filtration. Membrane separators can be operated in parallel or sequentially to promote maximum removal of solids and FOGs. In the case of electrocoagulation, reactor size and power input may be varied to provide the maximum efficiency for particle destabilization and separation. In addition, the pre-treatment module can be configured with redundant or module(s) that are controlled by the systems main control panel, in response to an alarm that signals when the pressure differential exceeds design parameters and to notify the operator that the module is approaching a fully loaded stage. An on-line turbidimeter (e.g. Hach type) can perform either system shutdown or activation of a motorized ball valve to shunt the flow to the backup pre-treatment module. The water from the pre-treatment module is pumped to an intermediate tank (typically a 3000 gallon tank) for settling and equalization. This tank also serves as a smoothing station for the system and allows for continuous operation.

A fine filtration module that employs diatomaceous earth pre-coated onto a matrix or septum can also be used. The fine filtration provides further removal of particulate matter as well as some adsorption of the FOGs and suspended solids. A single filtration vessei or multiple filtration vessels configured to operate in parallel can be used. Alternatively, fine filtration may be carried out through use of membrane separation to achieve the desired final filtered water quality. The effluent from the fine filtration module may be continuously monitored by on-line turbidimeters to assure that the target final quality is achieved. These turbidimeters interface with the main system control panel so that in the event the final water quality does not meet the designed standard, the entire system can be shutdown by way of a signal feedback loop.

After filtration of the water, further treatment may be carried out in a biological reactor that provides a cost effective way to remove BOD in wastewater. Any type of biological reactors may be used, such as, conventional activated sludge systems; packaged biological treatment systems; suspended carrier reactor (SCR) systems; or moving bed biological reactor (MBBR) systems. An MBBR system is a suspended growth system (e.g., activated sludge) having additional plastic media in the reactor to provide additional attached growth, resulting in higher biomass concentration and smaller reactor volume and footprint.

The water pumped using a centrifugal pump, end suction pump or top discharge pump to an oxidation and disinfection module for further treatment. The oxidation and disinfection module comprises an ozone generator, gas/liquid transfer and mixing devices and an ozone reactor assembly, that are all of conventional design. The ozonation process serves as the primary disinfection and color removal mechanism and can be continuously monitored against a predetermined standard. Gaseous ozone is injected into the system using the injection pump; e.g. a venture type gas/liquid mixing device (Mazzei injector), preferably in combination with appropriate hydraulic pipe sizing to achieve sufficient pressure and flow to promote the maximum mass transfer of the ozone gas into aqueous solution. The ozone is generated by a corona discharge type ozone machine using cryogenic oxygen or oxygen separated by pressure swing adsorption on-site as the source gas. Ozone generator sizing is based on U.S. EPA criteria for 3 to 4 log removal efficiency at an applied dose of a maximum of 7 ppm and a standard of 5 ppm. The ozonated water is then pumped through a pressure dwell manifold or a high efficiency, centrifugal gas/liquid mixing device to promote maximum dissolution of the ozone gas and then flows to an ozone contact tank (e.g. 304 stainless steel) sized to achieve a minimum of about 7 to 10 minutes contact time, to allow the ozone sufficient time to react with microorganisms and to achieve the maximum disinfection standard. The ozone contact tank is fitted with a sensor, e.g. a dissolved ozone measuring device, an Oxidation- Reduction Potential (ORP) probe, or conventional electronic voltage measuring device, that interfaces the system main control panel that can display dissolved ozone level or ORP on the panel front. ORP, dissolved ozone or both are controlled to achieve the desired disinfection standard determined by microbiological analysis at various set points to assure that the water is pathogen free. A 750-mv ORP set point, as established by the International Bottled Water Association (IBWA) as the oxidation level deemed sterile by drinking water standards and where microbiological activity is eliminated, is commonly used to indicate the sterility of water. Deviation from the desired level of disinfection, particularly if the An alarm is activated if dissolved ozone level or ORP falls below the programmed set point and the system can be shut down. Excess ozone gas and unreacted ozone gas may be removed by way of off-gas venting and may be collected and re-used in the system.

A final polish treatment comprising a settling tank or passage through fine media, bag filters or an activated carbon reactor may be used depending on the specific requirements imposed by regulatory authorities.

The treated effluent water from the system may then be piped to the chiller storage tanks for use as chiller makeup or to other re-use points, including but not limited to, the scalder, evisceration wash water, defeathering wash water, inside-outside carcass wash and sanitation cleanup water, to provide maximum volumetric re-use.

The recovered water may be chlorinated prior to re-introduction to the designated re-use point. The chlorination may be varied in dose to meet the requirements of different processing plant operations, generally as dictated by regulatory guidelines or plant specifications. Because the present invention provides for optimal re-chlorination dosing, additional food safety benefits can be obtained. In particular, optima! re-chlorination dosing for scalding, picking, stunning and flume type operations can be independently provided. This is an improvement over current practice, where adequate chlorination the process water at these points of operation may not be provided. In this light, it has been surprisingly discovered that by using optimally dosed chlorinated re-use water, there is a beneficial reduction in microorganisms on the carcasses being processed by such re-use water. For example, re-use water that is chlorinated with an optimal dose of chlorine or other approved disinfectant and then reintroduced to a scalder or similar heating process, causes a dramatic reduction in the levels of microorganisms associated with the carcasses over those found on carcasses treated by prior art processes. This is because during the scalding or heating steps, the pores and tissue membranes of the carcasses are open and more readily receive the surrounding water, i.e. the reintroduced chlorinated water.

The process and equipment of the present invention may advantageously be seif-regulating and self-monitoring, thereby requiring little operator intervention. The use of a Programmable Logic Controller (PLC) provides analog and digital input/output capability to continuously monitor and control the system and to notify operators of any system upsets or maintenance requirements. A main control panel with illuminated displays showing all component operating conditions can be used to control the system and provides flexibility of design to allow a wide choice of options and varying degrees of automation and control sophistication. For example, the main control panel interfaced with a variety of sensors and used to monitor a number of operation parameters, e.g. total volumetric flow using pulse type, digital flow meter with totalizer, etc., pressure using differential sensors fitted to both pre-treatment modules and final filtration modules, and turbidity at effluent of pre-treatment modules and at effluent of the ozone contact tank. An ambient ozone monitor can be installed adjacent to the chillers and other re-use points to continuously monitor ozone levels. By interfacing these controls and safety devices with the main control panel, alarm and notification to the plant operator can be provided in the event of any system upset and to shut down the system in the event that the final water quality fails to meet the established standards.

On-line safety is assured by use of a turbidimeter at various points in the system. In particular, in the event that turbidity of the treated water exceeds a predetermined level, the process may be instantaneously shut down or the operator can be notified to take appropriate remedial action, analyze the water for the presence of pathogens or contaminants and assure that the quality of water introduced to the designated re-use point meets appropriate "safe for the intended use" criteria.

The system of the present invention can also provide for backup by connecting to the main water lines of the plant using suitable float switches and valves that allow the introduction of city water in the event that there are any process system malfunctions, upsets or power interruptions. This helps ensure that food product processing can continue uninterrupted by any recovery system problems.

Additional re-use water quality assurance and safety provisions can be included in the present invention. For example, a solenoid shut-off valve can be fitted at the re-use water fill line for the chiller water storage tank. This solenoid valve is activated to close in the event that the water quality standard, ideally 5 NTU's turbidity, is not met. Further, the chiller water storage tank or the treatment system final product storage tank may include a backflow prevention valve on the city water inlet pipe to prevent backflow of the treated re-use water into the main city water line. Moreover, each filtration module may be fitted with pressure/vacuum differential sensors to continuously monitor the performance of filtration and provide alarms if pressure/ vacuum differential readings are out of prescribed ranges or when turbidity of primary filtration or effluent turbidity is out of range. In the event of system shut down, water from the treatment system can be recirculated within the treatment system or diverted to the main wastewater drain of the plant.

Further description of various system configurations according to different embodiments of the present invention are provided below.

Figure 1 is a schematic drawing of the waste water re-use system according to one embodiment of the present invention. Process waste water from primary processing plant 10, is fed into rotary screen 20, comprising a primary screen, pit and secondary screen. The waste water is pumped by pumps 24, to flow equalizer unit 30, fitted with a blower 32. Pumps 34, send the waste water from flow equalizer 30, to floe tubes 44. Acid, ferric and polymeric treatment agents may be added to the waste water from unit 40, prior to the water entering floe tubes 44. After treatment in floe tubes 44, the water is passed to at least one dissolved air flotation (DAF) device 50. Pump 54 send the water removed from the DAF device 50, to a separate tank (not shown). The bulk of the water from DAF device 50, passes to an Actiflo unit 60, for rapid flocculation and sedimentation. Solids and FOGs are passed to waste, and the bulk of the water is then passed by pumps 64, to an ozone treatment unit 70, that acts to disinfect the water and remove bacterial contaminants. The water then flows to secondary filtration unit 80. Chlorine may be added from chlorine unit 94, to the secondary filtration unit 80, to further treat the water. The preferred chlorine composition is a 12% chlorine bleach with a target 5 ppm and a flow of 2.6 gph. The treated water is then sent to re-use storage tank 90, as recycled water ready for plant use. When needed the recycled water is pumped from the re-use storage tank 90, by means of pumps 94.

Table I provides flow rate and composition of the waste water at various checkpoints of the re-use system as described above. These points are labeled on Figure 1 , wherein "a" is the influent from processing plant 10; "b" is the waste water entering pump 24; "c" is the waste water entering pump 34; "d" is the DAF float passing through pump 54; "e" is the waste water passing between DAF device 50, and Actiflo unit 60; T is the sludge from the DAF device 50; "g" is the waste water exiting Actiflo unit 60; "h" is the waste water after ozone treatment unit 70; "i" is the waste water from the secondary filtration unit 80; "j" is the re-use water emerging from re-use storage tank 90; and "k" is the bleach concentration for use in the secondary filtration unit 80. Table!

90 O O

O

Figure 2 is a schematic drawing of another embodiment water re-use system according to the present invention. Process water from processing plant 110, is fed into rotary screen 120, comprised of at least one of a primary screen, pit and secondary screen. The water is then passed to flow equalizer 130. Various chemical treatments via PAC 142, and an anionic polymer 144, are added to the water prior to treatment in floe tank 140. The water then flows to at least one dissolved air flotation (DAF) unit 150, to which santoquin 152, may be optionally added. Solids and FOGs from DAF 150, are treated in DAF sludge tank 190, to which chemicals, such as cationic polymer are added and the mixture is separated in centrifuge 195. Water from centrifuge 195, passes through belt press 198, and the resulting treated water is returned to flow equalization unit 130, while solids are sent to rendering. Oil from the centrifuge 195, is disposed.

The water from DAF 150, passes to anaerobic lagoon 160, and then to discharge well/vault 165. A portion of the water from discharge well/vault 165, is discharged to municipal waste, while another portion is passed to an anoxic tank 170, prior to entering aerobic reactor 175. A portions of the water from aerobic reactor 175, is treated in UF/membrane filtration unit 180, while sludge from aerobic reactor 175, is passed to belt press 198. A portion of the water from UF/membrane filtration unit 180, is recycled to anoxic tank 170, and another portion is either returned to UF/membrane unit 180, for further processing or to ozone and chlorine disinfection treatment unit 185. The treated water from unit 185, now cleaned and ready for reuse is stored in re-use storage 188, prior to returning to the processing plant.

Figure 3 is a schematic drawing of the waste water re-use system according to a further embodiment of the present invention. Process waste water from the process plant 310, is fed into rotary screen 320, comprising a primary screen, pit and secondary screen. The water is optionally sent through flow equalizer unit 330, prior to entering at least one unit 340, having acid, ferric and polymeric treatment agents. The water is then treated in a dissolved air flotation (DAF) device 350, to which ferric chloride 355, may be added. The water is then sent to a biotreatment unit 360, such as a moving bed biological reactor (MBBR) prior to treatment in another DAF 370. Solid and FOG waste from the DAF 350, and DAF 370, is sent for disposal to a municipal waste water treatment plant 375. Caustic and anti-foaming agents 358, may be added to the solid and FOG wastes from DAF 350. The treated water from second DAF 370, is treated in an ozone unit 380, to disinfect the water and remove bacterial contaminants, prior to filtration in filtration unit 390. Chlorine unit 395, treats the water prior to recycling the treated water to the processing plant 310. Feather and offal from rotary screen 320, is sent to rendering 325, as well as some sludge from DAF 350. Sludge from DAF 350, can also be composted for land application and landfill.

It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.

Claims

What is claimed is:

1. A process for the re-use of water from a carcass processing plant, comprising collecting waste water from at least one source other than a chiller bath operation; treating the collected waste water to remove fats, oils and grease (FOG), solids, organic compounds, animal proteins, microorganisms and pathogenic organisms; and returning the treated water to the processing plant for re-use.

2. A process according to claim 1 wherein the at least one source is a carcass final wash stream, an inside or outside carcass wash cabinet or another low load source stream.

3. A process according to claim 1 wherein treated water is re-used as chiller bath water, scalder water, evisceration wash water, defeathering wash water, inside or outside carcass wash water or sanitation cleanup water.

4. A process according to claim 1 wherein the amount of chiller bath water collected is in the range of twenty percent to forty percent of the total amount of waste water collected.

5. A process according to claim 1 wherein the processing plant is a poultry processing plant.

6. A process according to claim 1 wherein treating the collected waste water comprises removing solids from the collected water using a screen device; removing organic materials, including FOG, proteins, lipids, carbohydrates and small solid particles from the collected water using a floatation device; and removing further solid materials from the collected water using filtering operations.

7. A process according to claim 6 further comprising performing a fina! polish on the collected water.

8. A process according to claim 1 further comprising chlorinating the collected water prior to returning the treated water to the processing plant.

9. A system for recycling water for re-use in a carcass processing plant, comprising collecting means for collecting waste water from at least one source other than a chiller bath operation; and treating means to treat the collected waste water to remove fats, oils and grease (FOG), solids, organic compounds, animal proteins, microorganisms and pathogenic organisms.

10. A system according to claim 9 wherein the collecting means include coilectors located at a carcass final wash stream, an inside or outside carcass wash cabinet or another low load source stream.

11. A system according to claim 9 wherein the collecting means collects chiller bath water in an amount between twenty percent and forty percent of the total amount of waste water collected.

12. A system according to claim 9 wherein the processing plant is a poultry processing plant.

13. A system according to claim 9 wherein the treating means comprises a screening device, a flow equalizer tank, a floe tube unit, at least one DAF unit, an Actiflo unit, an ozone treatment unit, and a filtration unit.

14. A system according to claim 13 wherein the treating means further includes a chlorine treatment unit.

15. A system according to claim 9 wherein the treating means comprises a screening device, a flow equalizer tank, a floe tube unit, at least one DAF unit, an aerobic reactor unit, a UF/membrane treatment unit, and an ozone disinfection treatment unit.

16. A system according to claim 15 wherein the treating means further includes a chlorine treatment unit.

17. A system according to claim 9 wherein the treating means comprises a screening device, at least one DAF unit, a biotreatment unit, an ozone treatment unit and a filtration unit.

18. A system according to claim 17 wherein the treating means further includes a chlorine treatment unit.

19. A system according to claim 9 wherein the collecting means is located in close proximity to the source and comprises a screened sump.