AU2010200397B2 - Soil desalination system - Google Patents

Abstract

-17 A method of reducing the salinity near the surface of land by passing the water used to irrigate the land through a conduit or the like located in a water pipeline and which has located therein a member which has an electric potential and which causes the water and any entrained particles entering the device to effect a torturous path to thereby condition the water and then supplying the water to the land to be treated. The method can also assist water take up in irrigated land. Before Ground level After Ground level Salts in soil p 22Z2ZZ Salts in soil f. Fig 1 Control Untreated Treated Water retained in columns m 63 10 mL 60 % Better Fig 2

Description

Regulation 3.2 -1 AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT APPLICANT: Robert Uden NUMBER: FILING DATE: Invention Title: SOIL DESALINATION SYSTEM The following statement is a full description of this invention, including the best method of performing it known to me: -1 SOIL DESALINATION SYSTEM This invention relates to a soil desalination system. The system is particularly adapted to reduce the effect of salt in agricultural land and to cause the level of salt in such land, at a depth of the root system of the crops being grown 5 in the land, to reduce. It also has application in domestic gardens, housing, roadway and sporting field applications. Many parts of Australian urban areas, for example the Western Suburbs of Sydney and country towns such as Wagga, suffer from salinity in the soil and this, in domestic gardens, market gardens, public gardens, housing, roadway and sports applications, such 10 as golf courses, make it difficult for the owners, growers and ground's people to maintain satisfactory growth and the system is also suitable to limit the effects of salinity for these applications. It is an object of the invention to provide a method of reducing the effective salinity of arable land so as to permit the land to be used in a manner which is more efficient than has is previously been the case. The invention includes a method ofreducing the salinity near the surface of land including the steps of passing the water used to irrigate the land through a conduit or the like located in a water pipeline and which has located therein a member which has an electric potential and which causes the water and any entrained particles entering the device to 20 effect a torturous path to thereby condition the water and then supplying the water to the land to be treated. In a first form, the member is associated with an earth which may have a sacrificial anode therein to provide an electrical circuit. In a second form, an electric current can be passed through the member. Y:\Spec\Uden-desalination2PCT.wpd -2 The conduit can be made of a conducting material, although this is not essential to the invention. It is preferred that the shape of the member is such that the movement of the water is caused to be turbulent such that all or most of this contacts the member or the conduit s wall during passage through the conduit. In one preferred form of the invention, the member in the conduit may be made of stainless steel and 316 stainless is satisfactory. The member in the conduit may have a silver coating deposited thereon. It may be preferred that the earth connection is made by a sacrificial conductor such as a 10 zinc rod. The mechanics or physico-chemical basis for the operation of the invention is not fully understood. I have known for some time that a water conditioner which is similar in form to the conduit and member of this invention operates by reducing or eliminating the cohesion 15 between the mineral particles in the water. This effect is visible under an electron microscope, and reference to this is made in my Australian Patent 629473. What I have discovered, which is most surprising, is that when conditioned water is applied to the soil a transfer occurs in as much that the conditioned water appears to eliminates the cohesion between mineral and soil particles and the minerals tend to be 20 carried by the water downwardly toward the water table so that the mineralisation at the soil at root level is reduced. This will be discussed further later herein in relation to the attached soil analyses which confirm the lowering of salts and minerals in the soil profile, Y:\Spec\Uden-desalination2PCT.wpd -3 It is believed that the operation of the water conditioner, and its impact when "conditioned" water is discharged onto soils, can be understood in terms of molecular theory and electrochemical behaviour of water and ionic reactions. The water that passes over the diversion member within the conduit is subjected to an 5 electric current and turbulent flow. This process displaces electrons from the diversion member, which become "free electrons" in the solution. That is, the water becomes electron rich. Ions or colloids within the solution with lesser electronegativities capture these "free electrons", causing the negative ions (ie. anions) to remain in solution and colloids to remain in suspension, in preference to forming precipitated salts. 10 In addition, the highly turbulent nature of the water flow through the device results in further breakdown of the existing colloidal particles. This is an ideal situation for using conditioned water on soil affected by salinity both in agriculture and urban lands. Salinity occurs if the level of free ions in the soil are in excess, and thus toxic for the is vegetation grown in the soil. Ifthe conditioned water is used to irrigate crops it is distributed onto the soil via overhead spray, flood or drip irrigation systems. During infdtration through the soil, the ions are thought to remain in solution instead of either forming solid salts in the root zone or adsorbing onto the clay/soil particles. Since 20 clays are negatively charged, the electron rich water containing negatively charged solutes are repelled by the clays and flow downward below the root zone. Furthermore, the positive ions (i.e. cations) that were already adsorbed on the clays will be attracted to the negatively charged conditioned water and may be released from the Y:\Spec\Uden-desalination2PCT.wpd -4 clay particles and move down below the root zone, thus reducing the salinity of the soil within the root zone. This may also have the affect of improving the structure and fertility of the soil. Empirically, as set out hereunder, we have found that the soil upon which water which 5 passed through the system of the invention is used for irrigation reduces substantially in salinity and, at the same time, the friability of the soil is improved. In a preferred form of the invention we provide a conduit which has sufficient diameter to readily pass the quantity of water required which is preferably of a metal and which is earthed, possibly by way of a zinc rod which is a sacrificial rod, and provides a source of 10 electrons. This rod is preferably located into the ground a distance sufficient to provide a good earth and it is also preferred that the area concerned be maintained damp to again provide good conduction between the rod and the soil. Alternatively, low voltage regulated power supply provided either by mains power or 15 batteries may be used to provide a source of electrons. Located in the conduit there is a diversion member which is metallic and in one particular preferred embodiment is made from stainless steel and which can take different shapes, the main requirement being that by the diversion member itself or in some alternative way the water passing through the conduit is effectively diverted into a turbulent flow which 20 ensures that all of the water, at some stage during its passage through the conduit, makes contact with the diversion member or the interior of the conduit. The water passing from the conduit can then be used for irrigation whether agricultural or urban.. Y:\Spec\Uden-desalination2PCT.wpd -5 In order that the invention can be more readily understood, reference will be made to the following drawings, and tables which are located in the text. In the drawings: Fig 1 shows schematically the way in which the invention operates; 5 Fig 2 shows schematically the manner of effecting of a test relating to soil penetration The desalination system reduces the salinity of the soil by mobilising salt downwards Referring to Fig 1, this is diagrammatic of what is occurring in the Before and After soil analysis. 10 During the water conditioning process, the mineral particles in the water repel and separate from each other, this limits their ability to attach to the soil structures and root systems. The use of the system of the invention thus restricts the likelihood of build up of additional salts near the surface of the soil as the salts pass through the soil and, at the is same time, irrigating with conditioned water helps to flush the salts presently existing in the soil through the soil profile as illustrated in the figure. Dalby Queensland The system of the invention has been used in irrigating 1000 acres of cotton in Dalby, 20 Queensland and over a period of less than three (3) years the level of chloride 150 Y:\Spec\Uden-desalination2PCT.wpd -6 - 900 millimetres below the ground level, was lowered by 41%. The actual figures are set out in the tables below: Soil Analysis Irrigated Cotton Farm Dalby, QLD 5 Testing Agent Incitec Ltd, Gibson Island Murarrie, QLD and Crop Tech Pty Ltd, Bundaberg, QLD Before System After System 10 Samples 15014 Samples 24 &15015 and41 15 " June 1998 17 ' May 2001 BEFORE AFTER REDUCTION is pH 0-150mm 8.7 7.6 -12% Electrical Conductivity mS/cm 150-900mm 1.63 1.53 -6.10% Chloride mg/I 20 0-150mm 425 354 -17% 150-900mm 2050 1202 -41% Table 1 This was a most surprising and very satisfactory result. 25 Jugiong, New South Wales At a fanning property in Jugiong in New South Wales, the salinity problem was so great that there was a proposal to install underground drainage in an attempt to lower the sodium and chloride. Y:\Spec\Uden-desalination2PCT.wpd -7 To do this was going to be very expensive and, as an alternative, the system of the present invention was applied to the area using an overhead irrigation system, the chloride in the soil was reduced by 52% and total salt reduction was 42%. Table 2 following shows soil analysis reports in respect of soil at the Jugiong property 5 at effectively a twelve month interval between June 2000 and May 2001. Irrigated Farming property Jugiong NSW Testing Agent Incitec Pivot - Nutrient Advantage, Deniliquin NSW 10 Before System After System Sample 10088794 Sample 10204318 Date 1 9th Jun 2000 Date 14'" May 2001 BEFORE AFTER REDUCTION pH 7.0 6.8 -3% is Elec Cond. mS/cm 0.33 0.19 -42% Total Salts mg/I 980.0 564.0 -42% Sulphur mg/I 60.0 35.0 -41% Copper mg/I 0.5 0.3 -40% Manganese mg/I 28.0 12.0 -57% 20 Iron mg/I 82.0 70.0 -15% Sodium mg/ 184.0 115.0 -37% Chloride mg/ 290.0 140.0 -52% Table 2 25 Swimming Pool Backwash Water Table 3 shows the situation where back-wash water from a salt water swimming pool with a salt content of approx 6000 - 7000mg/lit of salt passed through the system and was discharged onto an area. This is equivalent to approximately 2 tonnes of salt. Soil samples were taken at various depths after approximately 200,000 litres of the salt 30 water were discharged onto the wet area over a period of 16 years. Test Site Y:\Spec\Uden-desalination2PCT.wpd -8 2 Cooramin Street *Samples taken by Horizon Soil & Water Wagga Wagga, NSW 2650 Tested by CSPB labs, Western Australia Sample date: 3.10.01 Site 1- Control Area (dry) s Site 2 -Treated (Back Wash area from salt water swimming pool) CONTROL - dry TREATED - wet REDUCTION TDS meq/kg 0-15cm 108 89 -17% 10 40-50cm 98 92 -6% 70-80cm 361 230 -36.2% Table 3 It will be seen that, at each depth, the total dissolved solids (TDS) content of the wet area was substantially less than that of the dry area. is These tests were carried out by an independent testing authority, CSPB Soil Laboratories in Western Australia. Soil samples were collected by Horizon Soil & Water in Wagga Wagga NSW. Sweihan UAE 20 Tests carried out by the Agricultural Research Laboratory in Abu Dhabi showed a considerable reduction in the sodium absorption ratio. (Table 4) When irrigating with a TDS at 11,000 mg/l in Sweihan UAE crop production increased by 340%. 25 SOIL ANALYSIS Agricultural Test Site Testing Agent Agri. Extension Section, Al Khatam Y:\Spec\Uden-desalination2PCT.wpd -9 Agricultural Research Laboratory, Abu Dhabi Municipality, UAE Untreated Treated Lab S4518 No1 Lab S4517 No2 5 Date 08* /02/98 Date 08/02/98 UNTREATED TREATED REDUCTION Conductivity,uS/cm 7600.0 6800.0 -10.50% Sodium meq/i 45.2 34.1 -24,50% 10 Calcium meq/ 36.6 32.3 -11.70% SAR 8.8 6.6 -25% ESP| 10.5| 7.8 -25.00% Table 4 is Denniliquin, New South Wales At an irrigation property in Deniliquin NSW soil tests were carried out 12 months apart on two paddocks growing lucerne and pasture grass. Y:\Spec\Uden-desalination2PCT.wpd -10 Paddock 1- Lucerne -: Chloride was lowered by 89%; Electrical Conductivity was lowered 69% and Sodium was lowered by 54%. (Table 5) SOIL ANALYSIS 5 Irrigation property Deniliquin NSW Testing Agent Incitec Pivot - Nutrient Advantage, Deniliquin NSW Paddock 1 Lucerne 10 Before system After system Sample 10158642 Sample 22411 Date 18/10/2002 Date 28/10/2003 15 BEFORE AFTER REDUCTION % pH (1:5 Water) 7.1 7.3 pH (1:5 CaCI 2 ) 6.4 6.3 Organic Carbon %C 1.1 1.0 -9% Nitrate Nitrogen mg/kg 7.2 5.3 -26% 20 Sulfate Sulfur (KC140) mglkg 33.0 2.7 -92% Phosphorus (Colwell) mg/kg 52.0 38.0 -27% Potassium (Colwell) mg/kg 240.0 200.0 -16% Potassium (Amm-acet.) meq/100g 0.54 0.32 -40% Calcium (Amm-acet.) meq/100g 4.5 3.3 -26% 25 Magnesium (Amm-acet.) meq/100g 3.0 3.0 0% Sodium (Amm-acet.) meq/100g 1.3 0.6 -54% Chloride mg/kg 220.0 24.0 -89% Elect. Conductivity dS/m 0.23 0.07 -69% Copper (DTPA) mg/kg 0.54 0.42 -22% 30 Zinc (DTPA) mg/kg 1.05 0.84 -20% Manganese (DTPA) mg/kg 26.0 25.0 -4% Cation Exch. Cap. meq/100g 9.46 7.2 -24% Calcium/Magnesium ratio 1.5 1.1 -26% Sodium % of cations (ESP) 14.0 8.5 -40% 35 Elec. Cond. (Sat. Ext.) dS/m 2.3 0.8 -65% Table 5 Paddock 2 - Pasture grass-: 40 Chloride was lowered by 63% and Electrical Conductivity was lowered by 37%. (Table 6) Y:\Spec\Uden-desalination2PCT.wpd -11 Sample 10158647 Sample 22333 Date 06/11/2002 Date 28/10/2003 BEFORE AFTER REDUCTON % 5 pH (1:5 Water) 6.5 6.7 pH (1:5 CaCl2) 5.8 5.9 Organic Carbon %C 2.5 2.6 3% Nitrate Nitrogen mg/kg 8.4 1.99 -76% Sulfate Sulfur (KC140) mg/kg 30.0 15.0 -50% 10 Phosphorus (Colwell) mg/kg 23.0 31.0 34% Potassium (Coiwell) mg/kg 190.0 200.0 5% Potassium (Amm-acet.) meq/10Og 0.41 0.48 18% Calcium (Amm-acet.) meq/100g 6.9 6.5 -5% Magnesium (Amm-acet.) meq/100g 5.83 6.5 10% is Sodium (Amm-acet.) meq/100g 2.3 2.3 0% Chloride mg/kg 380.0 140.0 -63% Elect. Conductivity dS/m 0.35 0.22 -37% Copper (DTPA) mg/kg 1.28 1.3 1% Zinc (DTPA) mg/kg 2.46 2.6 5% 20 Manganese (DTPA) mg/kg 22.0 17.0 -22% Cation Exch. Cap. meq/100g 15.52 15.8 1% Calcium/Magnesium ratio 1.18 1.0 -15% Sodium % of cations (ESP) 15.0 15.0 0% Elec. Cond. (Sat. Ext.) dS/m 3.5 1 .8 -48% 25 Table 6 Wagga Wagga City Goff Club 30 At the Wagga Wagga City Golf Club, even though the water is of good quality, rising salinity was a major concern on the 12th fairway for many years. Soil tests confirm salinity levels up to 7000mg/i. 35 In October 2001 the Golf Club agreed to set up a trial area using the soil desalination system to see what effect it would have on the surface salts killing the grass. To make a comparison a Conditioner was installed to one (1) sprinkler only on the 40 12th fairway in an area where salt encrustation of the soil was very evident. This was called Site 1. Site 2 was the adjacent sprinkler approx 78 meters distant. 45 The trial was to compare Site I - treated; with Site 2 - untreated. To establish an accurate assessment of the Conditioner's effect on the salt, it was decided that the application of fertilisers to Sites 1 and 2 would cease during the trial. Y:\Spec\Uden-desalination2PCT.wpd -12 After six months, April 2002, it was noted that the surface salt disappeared on Site 1, and the couch grass was showing vigorous growth. Site 2 remained salt effected and there was no evidence of couch grass growth. 5 After two years, September 2003, soil samples were taken at different levels from 0 -120mm; 120 - 21Omm and 210 - 330mm deep in Site I and Site 2. It can be seen from the soil analysis in Table 7 that the salt levels in Site I were considerably lower than Site 2. This was a direct result of the soil desalination. 10 It was observed that the couch grass had also grown over much of Site 1 area, whereas Site 2 was still salt effected with little or no evidence of couch grass growth. SOIL ANALYSIS 15 1 2 "' Fairway Wagga Wagga City Golf Club NSW Testing Agent Australian Nuclear Science & Technology Organization Sydney NSW Date Sampled 25/09/03 20 SITE I SITE 2 pH Treated Untreated % DIFFERENCE 0-120mm 7.44 6.76 9% 120-210mm 6.91 6.76 2% 25 210-330mm 6.72 7.03 -4.40% Electrical Conductivity EC (mS/cm) 0-120mm 1.71 1.78 -4% 30 120-210mm 1.17 2.62 -55% 210-330mm 1.5 2.78 -45% Sodium mg/I 0-120mm 237.0 197.0 20% 35 120-210mm 167.0 290,0 -42% 210-330mm 203.0 319.0 -36% Chloride mg/l 0-120mm 330.0 410.0 -19.5 40 120-210mm 220.0 650.0 -66% 210-330mm 300.0 710.0 -57.70% Table 7 45 Y:\Spec\Uden-desalination2PCT.wpd -13 Water Take Up Fig 2 illustrates water take up by soil using water conditioned for use in the invention as against non-treated water and a control. 5 The following is the report of water wetness test by soil column technique, carried out by Analytical and Biological Laboratories Method: A sample of soil containing 28% moisture by weight was added to a laboratory container that measured 300mm by 900mm. The soil was added to a depth of 450mm and allowed to settle for a period of seven days. io Two glass columns of 13mm ID were then adjusted in the soil so that the column ends were buried 150mm from the top of the soil surface. A total 100 nl of water, treated and untreated, were then added to the columns and allowed to stand undisturbed for a period of 48 hours A similar column was placed along side the first two columns to act as a control tube. 15 100mls of untreated water were also added to the control column. The result was shown in Table 8 below and it can be seen that substantially more of the treated water was taken up by the soil than was the case with either the control or the untreated water, 20 1 00mL water added to each Control Untreated Treated column Water retained by columns 68mL 63mL 41mL mL of water by difference into soil 32mL 37mL 59mL Uptake by soil 32% 37% 59% 25 SOIL CONSTITUTION Clay 18% by weight 30 Black soil 23% by weight Sandy loam 57% by weight Stone/Pebble 2% by weight Table 8 35 The simple demonstration of water percolation indicates that there is a change in the water which has been treated by the process of the invention which permits the water to be more readily absorbed by the ground than is ordinary water. Y:\Spec\Uden-desalination2PCT.wpd -14 This has an effect on water usage which could be quite substantial in the long term. If the water when treated is more readily absorbed, the amount lost by evaporation will be reduced thus making water use more efficient than has previously been the case. Although, as mentioned above, the mechanics of the system are not fully understood s the positive results from the tests which have been carried out by independent authorities obtained from the use of the method are clear. Y:\Spec\Uden-desalination2PCT.wpd

Claims (11)

1. A method of reducing the salinity near the surface of land including the steps of passing the water used to irrigate the land through a conduit or the like located in a water pipeline and which conduit has located therein a member which has an electric potential with a negative connection at the upstream side of the conductive member and which conduit causes the water and any entrained particles entering the device to become turbulent and effect a torturous path to thereby condition the water, and then supplying the water to the land to be treated.

2. A method as claimed in claim 1 wherein the movement of the water is such that all or most of this contacts the conductive member during its passage through the conduit.

3. A method as claimed in either claim 1 or claim 2 wherein the conduit is of a conducting material and is connected to the conductive member which conduit is connected to ground by way of a sacrificial anode so that current passes therethrough.

4. A method as claimed in claim 3 wherein the sacrificial anode is a zinc rod.

5. A method as claimed in claim 1 or claim 2 wherein one end of the conductive member is connected to a sacrificial anode.

6. A method as claimed in claim 5 wherein the sacrificial anode is a zinc rod.

7. A method as claimed in claim 1 or claim 2 wherein each end of the conductive member to connected to a DC source so that current passes therethrough. 16

8. A method as claimed in any preceding claim wherein the conductive member is of stainless steel.

9. A method as claimed in claim 8 wherein it is of 316 stainless steel.

10. A method as claimed in any preceding claim wherein the conductive member has a silver coating deposited thereon.

11. A method substantially as hereinbefore described.