P100/011 2815/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Licer Pty Ltd Actual Inventor Lance O'Connor Address for service is: WRAYS Ground Floor, 56 Ord Street West Perth WA 6005 Attorney code: WR Invention Title: Water Treatment Apparatus The following statement is a full description of this invention, including the best method of performing it known to me: 1 -2 "Water Treatment Apparatus" Field of the Invention The present invention relates to a water treatment apparatus. Background Art There are many instances where the treatment of water to alter its properties such as pH or conductivity or total acidity or to remove and or treat contaminants, is of benefit. This may be desirous because of a need to dispose of or relocate the water or to make it usable for certain purposes. Lime is known to be used to treat various forms of wastewater or to treat drinking water. The treatment generally involves the addition of lime to the water, followed by filtration to remove precipitated hydroxides. It is necessary to perform the filtration step under high pressure. Difficulties are encountered when using lime to treat water due to its propensity to agglomerate or gel when used at high concentrations. However, at low concentration, reaction rates with water are compromised. Prior art apparatus for the treatment of water with lime function by the addition of lime to the water to be treated and passing the mixture through a filter under high pressure. Over time, solids build up on the filter, thereby impeding the flow of the fluid through the filter. Eventually the flow of fluid through the filter may cease completely. Generally, a filter needs to be cleaned by either a method of removal or by back flushing/cleaning. This results in unnecessary "down-time" which can become a significant cost. The present invention has one object thereof to overcome substantially, or to at least provide a useful alternative to, the abovementioned problems associated with the prior art.
-3 The preceding discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge in Australia as at the priority date of the application. Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Disclosure of the Invention Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the invention includes all such variations and modifications. The invention also includes all of the steps, features, compositions and compounds referred to or indicated in the specification, individually or collectively and any and all combinations or any two or more of the steps or features. The present invention is not to be limited in scope by the specific embodiments described herein, which are intended for the purpose of exemplification only. Functionally equivalent products, compositions and methods are clearly within the scope of the invention as described herein. The entire disclosures of all publications (including patents, patent applications, journal articles, laboratory manuals, books, or other documents) cited herein are hereby incorporated by reference. In accordance with the present invention, there is provided a water treatment apparatus, the water treatment apparatus comprising a reservoir for holding reagent and a reaction chamber for reaction of reagent with a reactant, wherein the reservoir and the reaction chamber are in fluid communication with each other -4/1 and the reaction chamber is provided in the form of a conduit with water inlet means and water outlet means and reagent inlet means between the water inlet means and the water outlet means, such that in use, water enters the reaction chamber via the water inlet means, reagent enters the reaction chamber via the reagent inlet means, 5 reaction occurs between the reagent and the reactant to provide treated water and the treated water exits the reaction chamber via the water outlet. In a preferred aspect of the invention, there is provided a water treatment apparatus comprising a reservoir for holding reagent and a reaction chamber for reaction of reagent with a reactant, wherein the reservoir and the reaction chamber are in fluid 10 communication with each other and the reaction chamber is provided in the form of a conduit with water inlet means and water outlet means and reagent inlet means between the water inlet means and the water outlet means, and wherein the reaction chamber is curved on itself at two or more places along its length between the reagent inlet means and the water outlet means, and at two of said places, the 15 reaction chamber is curved on itself to provide a first substantially horizontal portion, an upwardly projecting portion, and a second substantially horizontal portion forming a substantially S-shape, and wherein at least one sensor and/or at least one meter are located at or near the upwardly projecting portion of the reaction chamber, such that in use, water enters the reaction chamber via the water inlet means, reagent 20 enters the reaction chamber via the reagent inlet means, reaction occurs between the reagent and the reactant to provide treated water and the treated water exits the reaction chamber via the water outlet. More preferably, the at least one sensor and/or at least one meter are located at or near the uppermost portion of the upwardly projecting portion of the reaction 25 chamber, and the reservoir is provided with a stirrer to inhibit the agglomeration of reagent particles. Even more preferably, a valve or a positive displacement pump controls the entry of reagent into the reaction chamber via the reagent inlet means. By maintaining a continuous flow of water through the water inlet means into the reaction chamber and out of the water outlet means, the water treatment apparatus 30 is advantageously adapted to function as a continuous process in the treatment of water. Preferably, the continuous flow of water is maintained - 4/2 Preferably, the reagent inlet means is provided in the form of a conduit between the reservoir and the reaction chamber and comprises means to control the flow of reagent into the reaction chamber. The means to control the flow of reagent into the reaction chamber may be provided in the form of a valve or a positive displacement 5 pump. Preferably, the water inlet means comprises means to control the flow of water into the reaction chamber. The means to control the flow of water into the reaction chamber may be provided in the form of a valve or a positive displacement pump or a pump of another nature or a head pressure of fluid. 10 Preferably, the water outlet means comprises means to control the flow of water out of the reaction chamber. The means to control the flow of water out of the reaction chamber may be provided in the form of a valve or other restrictive device. Preferably, the reaction chamber is a conduit is of substantially circular cross section. 15 Preferably, the reaction chamber is curved on itself at two places along its length between the reagent inlet and the water outlet to provide a first substantially -5 horizontal portion, an upwardly projecting portion and a second substantially horizontal portion. Depending on the angle of the upwardly projecting portion, the reaction chamber may appear as an S-shape. Preferably, the upwardly projecting portion is substantially vertical. Advantageously, the use of a reaction chamber with a first substantially horizontal portion, an upwardly projecting portion and a second substantially horizontal portion provides more efficient mixing of the reagent and the water. The reactant may be provided in the form of the water, or solutes in the water or particles suspended in the water. Where the reactant is the water, the reagent may react with the water to change the pH and/or conductivity and/or total acidity of the water. Preferably, the pH of treated water is between about 6.0 and about 8.5. Where the reagent is adapted to react with solutes in the water or particles suspended in the water, said reaction may result in precipitation of dissolved cations and/or dissolved anions. Advantageously, said precipitation may change the conductivity of the water. Where the pH of the water is to be decreased, the reagent is preferably provided in the form of an acid. Preferably, the acid is selected from citric acid, hydrochloric acid and sulphuric acid. Where the pH of the water is to be increased, the reagent is preferably provided in the form of calcium hydroxide and more preferably, lime and even more preferably, in the form of lime putty. Where the reagent is provided in the form of lime putty, the concentration of calcium hydroxide in the reservoir is preferably up to 40 % W/,. More preferably, the calcium hydroxide in the reservoir is provided at a concentration of between about 5 % W/w to about 25 % W/w -6 Preferably, the reagent is prepared by the addition of lime putty slurry at a concentration of 40 % W/w to the reservoir and addition of water to achieve the appropriate dilution. It should be appreciated that the concentration of lime in the reservoir will depend on a number of factors including the pH and the total acidity of the water to be treated as well the concentration and nature of any dissolved solids or suspended particles in the water to be treated. If the concentration of the lime in the reagent chamber is too high, then on introduction of the lime to the water, the lime may gel and settle to the bottom of the reaction chamber thereby reducing effectiveness of the lime. Calcium hydroxide particles have a tendency to agglomerate and form larger particles. Without being limited by theory, it is believed that as the lime concentration increases, the tendency for particles of calcium hydroxide to agglomerate increases. As the size of the particles of calcium hydroxide increases, the reaction rates of the particles with water decreases. Further, larger particles have a tendency to sink to the bottom of the reservoir and the reaction chamber. Preferably the size of the calcium hydroxide particles is between about 2 pm and about 50 xm. Preferably, the reservoir is provided with means to inhibit the agglomeration of calcium hydroxide particles. In one form of the invention, the reservoir is provided with a stirrer. It should be appreciated that the speed of the stirrer should be sufficient to maintain the calcium hydroxide particles in a suspended state and to inhibit coagulation of said particles and will depend on the concentration of lime in the reservoir. Where the concentration of the lime in the reservoir is up to 40 % w4, the stirring speed is preferably 1500 rpm. More preferably, the stirring speed is between 960 rpm and 1500 rpm -7 It should be appreciated that the dose rate of lime into the reaction chamber will depend on a number of factors including the properties of the water to be treated such as pH, conductivity, total acidity and the concentration of and nature of dissolved and suspended solids as well as the flow rate and volume of water to be treated. Preferably, the reaction chamber comprises at least one sensor and/or at least one meter located between the water inlet means and the water outlet means, the at least one sensor and/or at least one meter adapted to measure properties of the treated water such as flow rate, pH, conductivity and total acidity. Preferably, the at least one sensor and/or at least one meter are located at or near the uppermost portion of the upwardly projecting portion of the reaction chamber. Locating the sensors and meters on the upwardly projecting portion of the reaction chamber ensures that the sensors and meters remain submersed when in use. Preferably, the meter measuring the properties of treated water and the meter measuring properties of untreated water are in communication with a computer or programmable logic controller (PLC) adapted to control flow rate of the reagent into the reaction chamber. Preferably, the flow rate of water in the reaction chamber is between about 1 Ls-1 and about 90 Ls-1. It should be appreciated that treated water may contain suspended solids in the form of unreacted/undissolved lime as well as other calcium salts that may precipitate out (e.g. fluorides, sulphates, phosphates) and other metal hydroxides (e.g. iron and aluminium). In one form of the invention, the treated water may be disposed of in accordance with environmental regulations or stored for disposal or subsequent treatment (e.g. directed to a settling tank or pond). Advantageously, this negates the need for high pressure pumps known in the prior art to pump water through filters.
-8 In one form of the invention, the water treatment apparatus further comprises a water return conduit adapted to divert at least a portion of the treated water to the reservoir. Preferably, the water return conduit comprises a valve, adapted to control the flow of water into the reservoir. The returned water should be low in solids and the water return conduit should be located in a position where any solids have an opportunity to settle. Preferably, the water return conduit is located downstream of the upwardly projecting portion of the reaction chamber. More preferably, the water return conduit is located prior to the valve on the water outlet of the reaction chamber. In one form of the invention, potassium silicate is added to the reservoir to precipitate soluble iron from the water to be treated. The water treatment apparatus may comprise means for modifying the dynamics of fluid flow within the reaction chamber. Preferably, this means is located within the reaction chamber. In one form of the invention, the means may comprise at least one baffle and or mixing device. It should be appreciated that there may be provided more than one baffle or mixing device. The apparatus of the present invention is adapted to treat water from a variety of sources including dewatering, acid water, alkaline water, water run off into waterways caused by inundation or spillage, nutrient build up, algae bloom, sewage, acid mine and industrial wastewater discharges but not limited to these. Brief Description of the Drawings The water treatment apparatus in accordance with the present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawing, in which: Figure 1 is a side view of the water treatment apparatus in accordance with the present invention; and -9 Figure 2 is a plan view of the water treatment apparatus in accordance with the present invention; and Best Modes(s) For Carrying Out The Invention In Figure 1 there is shown a water treatment apparatus 10 in accordance with the present invention comprising a reservoir 12 for holding reagent and a reaction chamber 14 for reaction of reagent with a reactant, the reservoir 12 being in fluid communication with the reaction chamber 14. The reaction chamber 14 is provided in the form of a conduit with a water inlet 16 and a water outlet 18 and a reagent inlet 20 between the water inlet 16 and the water outlet 18. The reagent inlet 20 is provided in the form of a conduit of 19 mm diameter between the reservoir 12 and the reaction chamber 14 and comprises a valve 26, adapted to control the flow of reagent into the reaction chamber 14. The water inlet 16 comprises a valve 28, adapted to control the flow of water into the reaction chamber 14. The water outlet 18 comprises a valve 30, adapted to control the flow of water out of the reaction chamber 14. The reaction chamber 14 is a conduit is of substantially circular cross section and is curved on itself at two places along its length between the reagent inlet 20 and the water outlet 18 to provide a first substantially horizontal portion 32, an upwardly projecting portion 34 and a second substantially horizontal portion 36. As shown in Figure 1, the upwardly projecting portion 34 is substantially vertical. The reaction chamber 14 comprises a pH meter 38, total acidity meter 38, a conductivity meter 38 and a flow meter 38 located between the water inlet 16 and the water outlet 18. The meter 38 is located at or near the uppermost portion of the upwardly projecting portion 34 of the reaction chamber to ensure that the meter 38 remains underwater when in use. The water inlet 16 comprises a pH meter 40, total acidity meter 40, a conductivity meter 40 and a flow meter 40.
- 10 The meter 38 and the meter/s 40 are in communication with a computer, PLC or control device (not shown) adapted to control flow rate of untreated water and reagent into the reaction chamber 14. The computer is connected to a secondary control system (not shown) controlling the rate of addition of reagent to the reaction chamber 14. The water treatment apparatus 10 further comprises a water return conduit 42 adapted to divert at least a portion of the treated water to the reservoir 12 in the direction of arrow 44. The water return conduit 42 comprises a valve 46, adapted to control the flow of water into the reservoir. Prior to treatment, water from a variety of sources including dewatering, acid water, alkaline water, water run off into waterways caused by inundation or spillage, nutrient build up, algae bloom, sewage, acid mine and industrial wastewater discharges may be subjected to a coarse screening step prior to entering the water treatment apparatus 10. Where the water is an acid wastewater, the treatment of the water comprises increasing the pH of the water to between about 6.0 and about 8.5. A preferred form of treatment comprises the use of lime as the reagent. The lime reagent (or other types of reagents as required) is prepared by the addition of lime slurry at a concentration of 40 % w/, to the reservoir and addition of water to dilution to between about 5 % "/w to about 25 % W/,. The reservoir 12 is provided with a stirrer 45 to inhibit the agglomeration of calcium hydroxide particles. Where the concentration of the lime in the reservoir is up to 40 % w/,, the stirring speed should be about 1500 rpm. In use, water enters the reaction chamber 14 in the direction of the arrow 47 via the water inlet 16, reagent enters the reaction chamber 14 in the direction of the arrow 48 via the reagent inlet 20, reaction occurs between the reagent and the reactant to provide treated water and the treated water exits the reaction chamber 14 in the direction of the arrow 50 via the water outlet 18.
- 11 By maintaining a continuous flow of water through the water inlet 16 into the reaction chamber 14 and out of the water outlet 18, the water treatment apparatus 10 is advantageously adapted to function as a continuous process in the treatment of water. The flow of water is maintained by a pump or head of fluid (not shown) at a rate of between about 1 Ls< and about 90 Ls 1 . In the reaction chamber, the substantially vertical upwardly projecting portion assists in mixing the calcium hydroxide/or other reagent particles and the water. The turbulence created inhibits agglomeration of the particles. Depending on the constituents of the water to be treated, the treated water may contain precipitates such as metal hydroxides and oxides as well as other calcium salts. The treated water may be directed to a settling tank or pond etc. to remove solids. If it is necessary to fill the reservoir 12, a portion of the treated water may be redirected to the reservoir via the water return conduit. The apparatus of the present invention enables the control of lime concentrations in the reservoir and in the reaction chamber, the latter being controlled by water flow and reagent flow. Due to the very small particle sizes, reaction of the lime with water is extremely rapid, and due to rapid stirring in the reservoir it is possible to use higher concentrations of lime putty than the prior art. Example The following Example serves to more fully describe the manner of using the above-described invention, as well as to set fourth the best modes contemplated for carrying out various aspects of the invention. It is understood that this Example in no way serves to limit the true scope of this invention, but rather is presented for illustrative purposes. Twelve 25 kg bags of lime as a 40 % w/w slurry were added to a 1000 L reservoir with 750 L of water, providing a lime putty slurry with a concentration of 12 % W/w.
- 12 A high speed mechanical stirrer operating at 1480 rpm maintained the calcium hydroxide particles evenly distributed through the tank and eliminated agglomeration of the particles. The average particle size was 2 - 50 pm. The flow of water at pH 5.85 in the reaction chamber was 80 Ls- 1 through a pipe of 150 mm diameter and the feed rate of the lime slurry into the reaction chamber was 0.01 Ls-1 through a pipe of 19 mm diameter. The pH of the treated water was 7.25 and total acidity was reduced from 60 mg/kL CaCO 3 to 25 mg/kL CaCO 3 . After the lime putty slurry is pumped into the reaction chamber, the pH of the water is rapidly increased. There is about half a second before the water passes the meters at the top of the bend in the line. If it were not for the tiny particle sizes, there would not be enough time for the lime to react and increase the pH.