IL289380A - A combined treatment self-contained water recirculating system and method - Google Patents

Description

A COMBINED TREATMENT SELF-CONTAINED WATER RECIRCULATING SYSTEM AND METHOD TECHNICAL FIELD Embodiments of the invention relate to a self-contained water treatment system and method, and more specifically to a coagulation-flocculation-based self-contained water recirculating system and method, in particular for a fruit handling and packaging plant.

BACKGROUND Fruit packing plants and specifically banana or kiwi packing stations, typically include cleaning reservoirs where the fruit is washed with water. The water removes waste, insects, Latex (etc.) from the fruit. In order to reduce water consumption, water recirculation systems are used to remove suspended substances from the water before routing the water back to the cleaning tanks.

A major pollutant produced by fruit washing is Latex. Latex is an emulsion of polymer microparticles in an aqueous medium and, in nature, typically comes in the form of a milky fluid that includes proteins (and the like). Latex can be found in various fruits, such as Bananas, Kiwi, Avocado, Chestnuts (and the like).

Examples of water treatment processes include mechanic filtering, centrifugal separation, or protein skimmers typically used in municipal treatment facilities (or the like).

Protein skimmers remove organic compounds, including proteins and amino acids, from water by using the polarity of the protein itself in their process. Due to their intrinsic charge, water-borne proteins are either repelled or attracted by an air/water interface and thus can be described as either hydrophobic or hydrophilic. Protein skimmers generate bubbles into the water to form an interface for hydrophobic and hydrophilic organic molecules to collect on the bubble surface (the air/water interface).

Dissolved air flotation (DAF) is another water treatment process that removes suspended matter by dissolving air in the water or wastewater under pressure and then releasing the air at atmospheric pressure in a flotation tank. Tiny bubbles formed in the process adhere to the suspended matter, urging it to float to the water’s surface, where it may then be removed.

Other water treatment methods include flocculation and coagulation, which removes suspended solids (turbidity) from water by causing the suspended particles to aggregate into a slime, which settles out of the water.

Coagulation treatment usually neutralizes the negative electrical charge on the pollutant particles in a way that destabilizes the forces keeping colloids apart from each other.

This process could be done chemically by introducing coagulants (coagulation agents) and flocculants or electrically by changing the charge of the purified water.

Water treatment coagulants comprise positively charged molecules that, when added to the water and mixed, accomplish this charge neutralization. Inorganic, organic, or a combination of both coagulant types are typically used to treat water for suspended solids removal.

Flocculants gather the destabilized particles together and cause them to agglomerate and drop out of the solution. Examples of flocculants include low-, medium-, and high-molecular-weight polymers.

SUMMARY The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools, and methods which are meant to be exemplary and illustrative, not limiting in scope.

In an embodiment of the present invention, there is provided a self- contained combined system for water recirculation from and back towards fruit cleaning reservoir(s). The sys tem i ncludes a treatment portion comprising of sensing members, agent dosing members, cascading coagulation and flocculation members, and a flotation member, wherein the sensing members designed to analyze the water in terms of acidity, pollutants, or other parameters, the agent dosing members designed to add agents to the water at different stages/locations of the system according to the various applications of the water and/or the analysis made by said sensing members. Such agents include acidity control at (or at the vicinity of) the inlet of the treatment portion, coagulants, and flocculants at the correspondent cascading chamber or other.

The cascading coagulation and flocculation members are arranged to urge physical and chemical processes, forming flocs from suspended substances in the water and then urge water with flocs into the flotation portion, wherein the flotation portion is arranged to receive an incoming flow of bubbles for urging at least most of the flocs towards the upper surface of the water in the flotation portion.

In an embodiment, there is also provided a method for removing suspended substances from water in fruit cleaning tank(s), the method comprising: providing a self-contained system for recirculation water from and back towards fruit cleaning reservoir(s), providing a treatment portion based on sensing members, agent introducing members, cascading coagulation and flocculation members and a flotation member, wherein the sensing members designed to analyze the water in terms of acidity, pollutants to other parameters, the agent introducing members designed to add agents to the water at different stages/locations of the system according to the various applications of the water and/or the analysis made by said sensing members. Such agents include acidity control at (or at the vicinity of) the inlet of the treatment portion, coagulant and flocculant at the correspondent cascading chamber, or other.

The cascading coagulation and flocculation members are arranged to urge physical and chemical processes forming flocs from suspended substances in the water and then urge water with flocs into the flotation portion, wherein the flotation portion is arranged to receive an incoming flow of bubbles for urging at least most of the flocs towards the upper surface of the water in the flotation portion.

In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the figures and applying the following detailed descriptions.

BRIEF DESCRIPTION OF THE FIGURES Exemplary embodiments are illustrated in referenced figures. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive. The invention, however, both as to organization and method of operation, together with objects, features, and advantages thereof, may best be understood by reference to the following detailed description when read with the accompanying figures, in which: Fig.1 schematically shows an embodiment of a water recirculation system of the present invention; Fig.2 schematically shows a sensing member and an agent dosing member, specifically an acidity sensor and pH control agent dosing of an embodiment of the inlet used in a combined- treatment portion such as that shown in Figs. 1, 3, and 4; Fig.3 schematically shows an enlarged view of an embodiment of a treatment portion of the water recirculation system; Fig.4 schematically shows a top view of the treatment portion; Fig.5 schematically shows a cross-sectional view of an embodiment of a flotation tank used in the combined-treatment portion, such as that shown in Figs. 1, 3, and 4; and Fig.6 schematically shows a cross-sectional view of an embodiment of a flotation tank used in the combined-treatment portion, such as that shown in Figs. 1, 3, and 4.

It will be appreciated that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated within the figures to indicate like elements.

DETAILED DESCRIPTION Attention is first drawn to Fig. 1, illustrating a general schematic view of a water recirculation system according to an embodiment of the present invention, here arranged to recirculate water away and back towards cleaning reserviors12 where fruit, typically bananas, are washed. Such cleaning tanks and recirculation systems may typically be located at or adjacent to fruit packing p l a n t s, such as banana packing stations.

In this example, the system includes an optional intermediate pool 14 where a pump may be located for drawing water out and away from the cleaning tanks 12 in a downstream direction towards a combined-treatment portion 16 of the system.

The c o m b i n e d - t r e a t m e n t portion 16 in its various embodiments is arranged to remove, possibly suspended, Latex (and other pollutants) from the water – routing the cleaner water back towards the cleaning reservoirs 12 for reuse. Latex is typically an emulsion of polymer microparticles in an aqueous medium, and in nature, typically comes in the form of a milky fluid that includes proteins organic compounds, including proteins and amino acids (and the like).

In a non-binding example, a recirculation system such as the present invention system may be arranged to recirculate water at a possibly constant rate of about 60-0 percent of the total water in the cleaning tanks per hour. Thus, in accordance with this example, within about 1 or 2 hours, substantially all or most of the water in the cleaning tanks may undergo physical and/or chemical processes within the recirculation system, typically within the combined-treatment portion of the system.

The combined-treatment system relies on combined self-contained processes designed to provide the purified water to be reused in the fruit cleaning reservoir. The processes include initial filtering, pH control comprising sensing and dosing, coagulant dosing and mixing, flocculant dosing and mixing, floc separating, and final filtering.

Attention is now drawn to Fig. 2 depicts the pH control portion 280, comprising a sensing member 282 and a dosing member 284.

The agents used for coagulation (coagulants) form specific ions that are responsible for the coagulation process. However, the actual ions produced by these coagulants depend upon the pH of the water.

Therefore, at varying water pH values, the coagulation process may suffer from less than optimum ions being formed in the solution. pH that is too low may not allow the coagulation process to proceed, while high pH can cause a coagulated particle to redisperse. The size of the coagulated particles is also affected by pH, which, in turn, determines the density of the flocculated slime and its tendency and rate of settling out. pH control of the water as part of the combined-treatment is therefore essential to the coagulation-flocculation process as well as for the outcome quality of the recirculation combined treatment process.

Yet, it varies from application to application based on the water, the pollutants, the agents, and more. An industrial waste sample, for instance, may be subject to broader pH variations, requiring stepwise pH control. In contrast, a raw water sample for beverage production may only need slight adjustments for minor variations in pH and alkalinity. Fruit washing waters are usually of a lower pH (i.e., acidic). They, therefore, require a basicity agent to allow for optimal coagulation, yet the pH shouldn’t be too high for ensuring optimal flocculation.

In some embodiments, pH measurement and a subsequent pH adjustment may also be required within the treatment process itself or at the end of the process before streaming the purified water to the recirculating system.

It will be emphasized that the pH control members are essential for providing a self-contained combined treatment recirculation system.

The Attention is additionally drawn to Figs. 3 and 4 to provide closer views of an embodiment of a treatment portion 16 of the system. The treatment portion in this example is shown, including first and second (coagulation and flocculation) cascade chambers 18, and primary and secondary flotation tanks 22, 24. Within treatment portion 16, chemical and physical processes are arranged to occur to water flowing through the recirculation system - in order to remove Latex (and the like) in the form of flocs from the water.

Water is arranged to flow through the treatment portion by initially entering the first (coagulation) cascade chamber 18 at its inlet 1 (here, two such optional inlets are shown). Water then exits the first cascade chamber via its outlet 182 and flows onwards downstream to enter the second (flocculation) cascade chamber at its inlet 1. Water then exits the second cascade chamber via its outlet 2 and flows onwards downstream to enter the primary flotation tank 22 at its inlet 221. Water can then be seen exiting the primary flotation tank at its outlet 222 and entering the secondary flotation tank 24 at its inlet 241.

From the secondary flotation tank, water then flows out via its outlet 242 to be routed back towards the cleaning tanks 12.

A principle applicable to at least certain embodiments of the invention may be defined in that substantially all vessels in the treatment portion 16 are formed as connecting vessels so that water balances out to substantially the same level in all vessels (18, 22, and 24). In addition or alternatively, the flow of water through the treatment portion 16 may be solely or primarily urged by gravitational force between points of entry and exit of the flocculation portion. In the illustrated embodiment, this may be achieved by arranging the entry point into the treatment portion, here inlet 181, to be at a level Hin that is higher than a level Hout at the exit from the flocculation portion, here outlet 242. In a non-binding example, the difference in height between Hin minus Hout may be about 20 centimeters (or the like).

Such principles of ‘connecting vessels’ and/or ‘gravitational’ flow may render inessential any need of pumps (or the like) for urging water in-between subsequent containers in the treatment portion, thus providing for a smoother flow of water through the treatment portion that assists in the formation and/or maintaining of flocs created by the physical and chemical processes applied to the water. That is to say that the absence of pumps (or the like) in at least certain embodiments may be of a benefit in reducing exposure of the water during the floc formation process to pressure forces typically applied upon water as in passes through and/or is urged by a pump, forces that may un- clump the forming flocs.

The route of water through treatment portion 16 accordingly starts in the discussed embodiment at the initial filter and the pH control member, located in or in the vicinity of the inlet of the coagulation and flocculation cascade chambers 18. Then, as it is urged up to inlet 181, water may pass through a static mixer located within the tubing that channels the water towards inlet 181. At first cascade chamber 18 or slightly before, a coagulant agent may be added to the water in order to destabilize charged particles in the water (i.e., the suspended Latex and the like arriving from the cleaning tanks). Then, the water flows through the first (coagulation) cascade chamber 18, possibly in a cascading manner between vertical baffles 187 passing above and below subsequent baffles. The first cascade chamber 18 may include mixers 17 (here are two such mixers) that assist in properly dispersing the coagulant in order to promote particle collisions required for achieving good coagulation. Such mixers may be arranged to rotate at a suitable chosen RPM.

At the second (flocculation) cascade chamber, a flocculant agent may be added to the water in order to possibly increase the average particle size of the flocs being formed. The water flows through the second cascade chamber, possibly also in a cascading manner between vertical baffles 7 passing above and below subsequent baffles. The second cascade chamber may include mixers 19 (here is one such mixer) that provide a more gentle mixing stage, aimed at increasing the particle size from, e.g., submicroscopic micro flocs to visible suspended particles. Such mixer may be arranged to rotate at a different or similar RPM.

Preferably the physical processes occurring within the coagulation and flocculation cascade chambers coupled with the chemical processes assisted by the additions of the coagulant and flocculant agents - assist in the formation of flocs that exit the second cascade chamber at its outlet 202 and enter the primary flotation tank 22 at its inlet 221.

Attention is now drawn also to Fig. 5 and 6, The primary flotation tank 22 includes a bubble generator 26 that preferably forms Micro and, more preferably, Nano-sized bubbles within the primary flotation tank in order to urge the arriving flocs upwards due to buoyancy of the bubbles.

The bubbles may utilize polarity forces to collect molecules of flocs formed within the first and second cascade chambers at the surfaces of the bubbles (i.e., the air/water interfaces of the bubbles). To assist in forming such suitable polarities, the processes occurring at the treatment portion 16 may be suitably controlled.

In one example, in a treatment portion 16 utilizing a bubble generator 26 forming bubbles having typical negative polarities, the chemical processes applied to form the flocs (e.g., by the coagulant and flocculant agents) may be suitably controlled so that the polarity of the resulting flocs arriving at the primary flotation tank may be positive (at least at their boundaries) in order to promote attraction between the bubbles and flocs.

In an embodiment of the present invention, a foaming agent 36, such as sodium lauryl sulfate (SLS), may be added to flotation tank 22, generally adjacent to where the rising flocs emerge by bubble generator 26. Such foaming agent forms or assist in forming a film of foam that attaches to the flocs arriving at the water’s upper surface that can then be easily removed from the flotation tank, e.g., towards a drain 38 where the foam including flocs can be evacuated. Using a foaming agent as a medium or means for removing flocs away from the tanks may be useful in reducing the loss of water that may otherwise be required for this process.

Water existing in fruit cleaning reservoirs that are intended to be cleaned by at least certain embodiments of recirculation systems of the present invention - may include suspended substances (e.g., Latex, dirt, and the like) in some cases at a relative low PPM, e.g., at a measure of below about 30 PPM or even lower below about PPM. In some cases, the average particle size of such suspended particles may be less than about 100 microns (e.g., in cross-section) and, in some instances, less than about 50 microns.

Such relative low percentage of suspended substances in the water of fruit cleaning reservoirs - may form flocs with, e.g., lower bondage forces between molecules – and thus may be considered as "weaker" flocs relative to flocs formed in bodies of water that have a higher percentage of substances to be removed (e.g., 2000 PPM and above) – such as in municipal treatment facilities (or the like).

Thus, in an aspect of the present invention – the addition of foaming agent may be aimed at assisting in the formation and/or removal of such "weaker" flocs formed by the relative "cleaner" water typically encountered in fruit cleaning reservoirs, which at least certain embodiments of recirculation systems of the present invention – may be aimed at treating.

With attention drawn back to Fig. 6, water flows downstream through the outlet of the primary flotation tank 22 towards and into the secondary flotation tank 24 through its inlet 241. The water flowing into the secondary flotation tank may carry with it at least some bubbles, flocs, and foaming agent - thus urging the possible formation of a secondary process of accumulation at the upper surface of the secondary tank of flocs. An outlet 242 of the secondary flotation tank may be adapted to collect water from a relatively lower portion of the tank, which typically may be exposed to substantially cleaner water with substantially fewer suspended materials (such as Latex and the like). This cleaner water exiting the combined-treatment portion may then flow back towards the fruit cleaning tanks 12.

In the description and claims of the present application, each of the verbs, "comprise", "include" and "have", and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb.

Furthermore, while the present application or technology has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and non-restrictive; the technology is thus not limited to the disclosed embodiments. Variations to the disclosed embodiments can be understood and effected by those skilled in the art and practicing the claimed technology, from a study of the drawings, the technology, and the appended claims.

In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or another unit may fulfill the functions of several items recited in the claims. The mere fact that specific measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

The present technology is also understood to encompass the exact terms, features, numerical values or ranges, etc., if in here such terms, features, numerical values or ranges, etc. are referred to in connection with terms such as "about, ca., substantially, generally, at least" etc.

In other words, "about 3" shall also comprise "3" or "substantially perpendicular" shall also comprise "perpendicular". Any reference signs in the claims should not be considered as limiting the scope.

Although the present embodiments have been described to a certain degree of particularity, it should be understood that various alterations and modifications could be made without departing from the scope of the invention as hereinafter claimed.

Claims (9)

5 CLAIMS

1. A self-contained combined-treatment portion of a water recirculating system of fruit cleaning reservoir(s), comprising, pH control module, coagulation, and flocculation portions and a floatation portion, wherein 10 said pH control module comprising a sensing member and a dosing member, and wherein said sensing member analyzes the pH of the water and said dosing member add an acidized or basicsizer agent to the water according to said analysis, and wherein said coagulation and flocculation portion is arranged 15 to urge and/or undergo physical and chemical processes forming flocs from suspended substances, such as Latex, in the water and then communicate water with flocs into said flotation portion and wherein, said flotation portion is arranged to receive an incoming flow of 20 bubbles for urging at least most of the flocs towards the upper surface of the water in the flotation portion. 5

2. A self-contained combined-treatment portion of a water recirculating system of fruit cleaning reservoir(s) of claim 1, further comprising a pre-filter, said pre-filter is located between the system reservoir(s) and said coagulation and flocculation portions. 10

3. A self-contained combined-treatment portion of a water recirculating system of fruit cleaning reservoir(s) of claim 2, wherein said filter size is between 100 and 400 microns, and its configuration is selected from disk or screen.

4. A self-contained combined-treatment portion of a water 15 recirculating system of fruit cleaning reservoir(s) of claim 1, wherein said pH control modules location is selected from: the vicinity of said combined-treatment portion inlet or outlet, said coagulation portion, said flocculation portion, said floating portion, or any combination thereof. 20 5. A self-contained combined-treatment portion of a water recirculating system of fruit cleaning reservoir(s) of claim 1, wherein said coagulation and flocculation portion comprises first and second cascading chambers and the flotation portion

5.comprises primary and secondary flotation tanks, and wherein the flow of water is from the first towards the second cascading chamber and from there towards the primary and then towards the secondary flotation tanks.

6. A self-contained combined-treatment portion of a water 10 recirculating system of fruit cleaning reservoir(s) of claim 1, wherein water entering said coagulation and flocculation portion at its inlet is urged via gravitational forces to flow from there onwards downstream to exit the flotation portion at its outlet, wherein the urging of flow through the flocculation 15 portion is preferably substantially solely powered by gravitational forces.

7. A self-contained combined-treatment portion of a water recirculating system of fruit cleaning reservoir(s) of any one of the preceding claims, wherein the polarity of the bubbles is 20 generally negative, and the chemical and/or physical processes form flocs comprising a generally positive polarity, to preferably be generally attracted to bubbles.

8. A self-contained combined-treatment portion of a water 5 recirculating system of fruit cleaning reservoir(s) of any one of the preceding claims, further comprising adding a foaming agent to the flotation portion to generally form foam adjacent on the upper surface of the water in the flotation portion for attaching to floating flocs. 10

9. A method for removing suspended substances from water in fruit cleaning reservoir(s), the method comprises a combined treatment wherein said combined treatment comprises pH control, coagulation, and flocculation process and a floatation process. Wherein said processes are carried out in a self- 15 contained portion of any of previous claims.