GB2192875A - Control of liquid treatment processes - Google Patents
Control of liquid treatment processes Download PDFInfo
- Publication number
- GB2192875A GB2192875A GB08713923A GB8713923A GB2192875A GB 2192875 A GB2192875 A GB 2192875A GB 08713923 A GB08713923 A GB 08713923A GB 8713923 A GB8713923 A GB 8713923A GB 2192875 A GB2192875 A GB 2192875A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid
- additive
- water
- tower
- monitoring
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 239000007788 liquid Substances 0.000 title claims abstract description 157
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000011282 treatment Methods 0.000 title claims abstract description 17
- 230000008569 process Effects 0.000 title claims description 11
- 239000000654 additive Substances 0.000 claims abstract description 61
- 230000000996 additive effect Effects 0.000 claims abstract description 59
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 52
- 238000012544 monitoring process Methods 0.000 claims abstract description 38
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims abstract description 15
- 239000007787 solid Substances 0.000 claims abstract description 9
- 230000000694 effects Effects 0.000 claims abstract description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 68
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 34
- 239000002253 acid Substances 0.000 claims description 24
- 239000000203 mixture Substances 0.000 claims description 24
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 21
- 239000001301 oxygen Substances 0.000 claims description 21
- 229910052760 oxygen Inorganic materials 0.000 claims description 21
- 241000196324 Embryophyta Species 0.000 claims description 19
- 239000007789 gas Substances 0.000 claims description 14
- 235000015097 nutrients Nutrition 0.000 claims description 13
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 9
- 229910017604 nitric acid Inorganic materials 0.000 claims description 9
- 230000008901 benefit Effects 0.000 claims description 7
- 239000000523 sample Substances 0.000 claims description 6
- 230000005587 bubbling Effects 0.000 claims description 5
- 239000001569 carbon dioxide Substances 0.000 claims description 5
- 239000008394 flocculating agent Substances 0.000 claims description 5
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 239000006185 dispersion Substances 0.000 claims description 4
- 238000012806 monitoring device Methods 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 4
- 230000001954 sterilising effect Effects 0.000 claims description 4
- 239000002245 particle Substances 0.000 claims description 3
- 229910021538 borax Inorganic materials 0.000 claims description 2
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000007613 environmental effect Effects 0.000 claims description 2
- ZZUFCTLCJUWOSV-UHFFFAOYSA-N furosemide Chemical compound C1=C(Cl)C(S(=O)(=O)N)=CC(C(O)=O)=C1NCC1=CC=CO1 ZZUFCTLCJUWOSV-UHFFFAOYSA-N 0.000 claims description 2
- 238000006386 neutralization reaction Methods 0.000 claims description 2
- 231100001184 nonphytotoxic Toxicity 0.000 claims description 2
- 150000002978 peroxides Chemical class 0.000 claims description 2
- 229960001922 sodium perborate Drugs 0.000 claims description 2
- 235000010339 sodium tetraborate Nutrition 0.000 claims description 2
- YKLJGMBLPUQQOI-UHFFFAOYSA-M sodium;oxidooxy(oxo)borane Chemical compound [Na+].[O-]OB=O YKLJGMBLPUQQOI-UHFFFAOYSA-M 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims description 2
- 238000004659 sterilization and disinfection Methods 0.000 claims description 2
- 239000004575 stone Substances 0.000 claims description 2
- 230000001502 supplementing effect Effects 0.000 claims description 2
- BSVBQGMMJUBVOD-UHFFFAOYSA-N trisodium borate Chemical compound [Na+].[Na+].[Na+].[O-]B([O-])[O-] BSVBQGMMJUBVOD-UHFFFAOYSA-N 0.000 claims description 2
- AQLJVWUFPCUVLO-UHFFFAOYSA-N urea hydrogen peroxide Chemical compound OO.NC(N)=O AQLJVWUFPCUVLO-UHFFFAOYSA-N 0.000 claims description 2
- -1 urea peroxide Chemical class 0.000 claims description 2
- 238000010923 batch production Methods 0.000 abstract 1
- 239000000725 suspension Substances 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 13
- 238000009826 distribution Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000020 calcium bicarbonate Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000012272 crop production Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000005189 flocculation Methods 0.000 description 1
- 230000016615 flocculation Effects 0.000 description 1
- 210000004209 hair Anatomy 0.000 description 1
- 239000008233 hard water Substances 0.000 description 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 description 1
- 238000003898 horticulture Methods 0.000 description 1
- 239000006193 liquid solution Substances 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011490 mineral wool Substances 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 230000000638 stimulation Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
- A01G31/00—Soilless cultivation, e.g. hydroponics
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D11/00—Control of flow ratio
- G05D11/02—Controlling ratio of two or more flows of fluid or fluent material
- G05D11/13—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means
- G05D11/135—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by sensing at least one property of the mixture
- G05D11/138—Controlling ratio of two or more flows of fluid or fluent material characterised by the use of electric means by sensing at least one property of the mixture by sensing the concentration of the mixture, e.g. measuring pH value
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D21/00—Control of chemical or physico-chemical variables, e.g. pH value
- G05D21/02—Control of chemical or physico-chemical variables, e.g. pH value characterised by the use of electric means
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/20—Treatment of water, waste water, or sewage by degassing, i.e. liberation of dissolved gases
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/30—Treatment of water, waste water, or sewage by irradiation
- C02F1/32—Treatment of water, waste water, or sewage by irradiation with ultraviolet light
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/34—Treatment of water, waste water, or sewage with mechanical oscillations
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/68—Treatment of water, waste water, or sewage by addition of specified substances, e.g. trace elements, for ameliorating potable water
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/02—Non-contaminated water, e.g. for industrial water supply
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/001—Upstream control, i.e. monitoring for predictive control
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/06—Controlling or monitoring parameters in water treatment pH
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/10—Solids, e.g. total solids [TS], total suspended solids [TSS] or volatile solids [VS]
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/40—Liquid flow rate
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2303/00—Specific treatment goals
- C02F2303/04—Disinfection
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F5/00—Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents
Abstract
The invention relates to methods and apparatus for treating liquids and lends itself to the continuous processing of many liquid treatments currently effected by batch processes. The raw liquid is continuously passed through a monitoring station where a condition of the liquid is monitored and an additive is supplied to the liquid downstream of the monitoring station in dependence upon the monitored condition, before the liquid and additive are passed to a mixer. Thus, the additive is supplied to the liquid in the exact amount necessary to effect the desired condition of the liquid. The invention has a wide range of uses including removal of solids in suspension in the liquid and the processing of hydroponic feed liquids. In particular the invention is useful for softening water having excessive bicarbonate content.
Description
SPECIFICATION
Improvements in or relating to liquid treatment processes
This invention relates to liquid treatment processes and, more particularly, to liquid treatment processes wherein some chemical additive is introduced into the liquid to affect some change in the overall composition of the liquid.
It is well known in the art to introduce an additive to a liquid and then to effect some mixing of the liquid/additive combination in order to disperse the additive through the liquid and such prior art mixers comprise mechanical mixers or vibration mixers.
The prior art mechanical mixers are wasteful of energy and to obtain an intimate distribution of the additive through the liquid such mixers must operate on a batch processing and do not readily lend themselves to continuous processing. With prior art vibration methods for mixing it is the practise to vibrate the liquid by vibrating the container for the liquid and this once again leads to batch mixing and a waste of energy.
A further problem with liquid treatment processes, particularly when the amount of additive is determined upon a condition of the liquid, is that the liquid must be sampled to determine the amount of additive to be included and the condition of the liquid may vary so that the amount of additive calculated for the monitored sample may not be the correct amount to achieve the desired result.
The present invention seeks to provide a method for treating a liquid comprising the steps of continuously passing the raw liquid through a monitoring station arranged to monitor a condition of the liquid, continuously supplying an additive to the liquid downstream of the monitoring station in direct dependance upon the monitored condition of the liquid and continuously passing the liquid/additive combination through a mixer station to obtain an intimate dispersion of the additive through the liquid.
In one embodiment in accordance with the invention, for treating a liquid to remove solid particles in dispersion in the liquid, the method preferably includes the steps of monitoring the solids contents of the liquid passing through said monitoring station and supplying an additive comprising a flocculating agent to the liquid, in dependence upon the monitored solids content of the liquid.
In another embodiment of the invention for softening water, the method comprises the steps of monitoring the pH of the water passing through said monitoring station and supplying an additive in the form of an acid, selected to neutralize the bicarbonate content of the water, in dependance upon the monitored pH of the water.
Preferably the method includes the steps of passing the liquid additive combination through a vibration zone and vibrating said liquid additive mixture.
Preferably the method includes the step of passing a gas, in the form discrete bubbles, through the liquid/additive mixture.
Preferably the method includes the steps of selecting the gas to effect a chemical reaction with the liquid/additive mixture.
In one embodiment of the invention, for hydroponic feeding of plants, the method preferably comprises the steps of passing raw water through a pH monitoring station, continuously monitoring the pH of the water passing through said station, continuously supplying a nitric acid to the water downstream of said pH monitoring station in direct dependance upon the monitored pH condition, passing the water and acid mixture through a mixer station to intimately mix the said water and acid, bubbling oxygen through the mixture to remove CO2 from said mixture and subsequently adding nutrients to the treated water.
Preferably the method includes the steps of sterilizing the liquid or the liquid/additive mixture.
Conveniently, the sterilization step is effected by ultra-violet radiation.
The invention also envisages apparatus for performing the method according to the invention and comprising a flow duct for a liquid, monitoring means for monitoring a condition of the liquid flow at a fixed location along said flow path, means for supplying an additive to said liquid flow path downstream of said monitoring means, control means for controlling the supply of additive to said flow path in dependance upon the monitored condition of the liquid and means for mixing said liquid and said additive.
In one embodiment in accordance with the invention the monitoring means comprise a light source and a light sensitive device, spaced apart across the flow path, and whereby the degree of contamination of the liquid solids particles is monitored by the intensity of the light falling on the light sensitive device.
In another method in accordance with the invention the said monitoring means comprise a pH monitoring device, the probe of which is inserted into the liquid flow path.
Preferably the means supplying additives to the liquid flow path comprises a reservoir of additive and a metering pump. With such an arrangement the control means for controlling the supply of additive is conveniently an electronics device, arranged to receive signals from the monitoring means and arranged to drive the metering pump in dependance upon the signals received from the monitoring means.
Preferably the means for mixing said liquid and said additive comprise a hydro brake mixer.
In a preferred embodiment in accordance with the invention the apparatus includes means for agitating the liquid/additive mixture, in one such embodiment the agitating means may conveniently comprise means for vibrating the liquid and in another embodiment the apparatus includes means for agitating the liquid/additive mixture by bubbling gas in discrete bubbles through the liquid/additive mixture.
When the apparatus includes means for vibrating the liquid/additive mixture the liquid flow path is conveniently an open channel with the vibrator at least partially inserted into the liquid flow along the said channel.
In a preferred embodiment in accordance with the present invention the apparatus includes a substantially vertical tower with a liquid/additive inlet at or near its upper regions and a liquid/ additive outlet at or near its lower regions. In one form the apparatus includes a spray at or near the upper regions of the tower through which the liquid/additive mixture is sprayed so as to fall down the tower in the form of discrete droplets. In another embodiment in accordance with the invention the tower is fully charged with liquid/additive and the apparatus includes means for injecting gas into the lower regions of the tower, whereupon the gas rises up the tower in the form of discrete bubbles.
The method and apparatus proposed by the present invention have a wide range of uses in that they can be used to process large volume treatment of liquids, many of which are currently treated in batches and, because of its large volume capability with relatively low cost, many liquid treatments not possible or economically viable by prior art treatment processes can now be commercially exploited.
In one 'such use the method can be practised to remove fine particulate solids from a liquid, useful for example in a sewage treatment process. By adding a flocculating agent to the liquid before passing the liquid to the mixer, thereby affecting a general distribution of the flocculating agent through the liquid, and then passing the liquid through a mixing zone and an agitation zone, the vibrations transmitted into the liquid will affect an intimate mixing of the distributed flocculating agent and particulates thus enhancing flocculation to facilitate removal of the particulates downstream of the vibration-zone.
The invention also affords advantages in horticulture, particularly in so-called hydroponic systems of plant production and wherein the plant roots are supported in an inert bed, for example rock-wool, the greenhouse is preferably maintained at high carbon dioxide atmosphere, and the root system of the plant is supplied with a liquid the contents of which are carefully balanced to supply the plant roots with all the nutrients the plant requires for maximum growth stimulation.
A limitation of this system is apparent when recycling the hydroponic solution is attempted. In practise the plant roots remove inter alia oxygen from the hydroponic liquid, and aqueous solution can absorb carbon dioxide from the atmosphere in the greenhouse and the liquid exhausted from the greenhouse, low in oxygen and high in carbon dioxide, is discarded often to the detriment of the environment. The method, proposed by the present invention allows such exhausted liquid to be treated to remove carbpn dioxide and replenish oxygen content, whereupon it can be topped up with nutrients and returned to the greenhouse.
A difficulty with the preparation of hydroponic feeds, particularly in so called "hard" water areas, is control oflthe pH. - In hard water the calcium and magnesium are in the form of bicarbonates and the acid used to neutralize the bicarbonates and thereby control the pH is conveniently nitric acid, since nitrates represent a vital part of the hydroponic feed.
In conventional hydroponic feed processes the pH of the raw water is monitored and the acid is added before the liquid passes a nutrient balancing device, such as the well known VOCOM device.
However, when a bicarbonate is neutralized with an acid the equation is typically as follows; Ca(HCO3)2+2HNQCa(NQ)2+2CQ+2H2O It is well observed that CO2 is not rapidly evolved in dilute solutions e.g. when titrated with acid a bicarbonate solution is seen to drift back to the alkaline side if the titration solution is left to stand at a first end point.
Thus, whilst the pH may be lowered, the liquid is saturated with CO2 and low in oxygen content. When such solution is supplied to the plant root system, the CO2 will come out of solution and form minute bubbles of CO2 gas at the root hairs. Thus the plants become saturated with CO2 and deprived of oxygen with an immediate rise in pH to the detriment of the plant.
The present invention will now be described further by way of example with reference to the accompanying drawings in which the single figure shows, diagrammatically, one liquid treatment plant useful for treating water for a hydroponic system for commercial crop production.
In the illustrated embodiment raw water is supplied via a pipe 11, a meter 12 records the rate of flow and signals flow rate to a control device 13, the water in pipe 11 then passes a pH monitoring device 14, conveniently pH electrodes, which signals and the pH of the water to the control device 13 and device 13, in response to the signals from meter 12 and device 14, pumps nitric acid (HNO3) from a supply duct 15 into the water flowing from pipe 11 to the inlet of mixer 16, in this example a so-called "HYDRO-BRAKE", wherein the water and acid are intimately mixed.
From mixer 16 the water and acid mixture flows to a vibrator channel 17 above which is located a vibrator 18 with a probe 19 projecting into the liquid flow along channel 17. The vibrator 18 cause probe 19 to emit vibrations at ultrasonic frequency into the liquid in channel 17 and such vibrations assist in the neutralization of the bicarbonates and force CO2 in solution in the liquid out of solution to form minute bubbles of gas in the liquid.
The liquid from channel 17 then passes to the upper regions of a tower 20, conveniently entering tangentially into said upper regions and exhausting tangentially from the lower regions of the tower to generate spiral flows within the tower. Air, introduced under pressure into the lower regions of the tower via a pipe 21, is released from a bubbling device 22, such as a porous stone, in the lower regions of the tower. The liquid flowing down the tower 20 is thus scrubbed of the gaseous CO2 by the air bubbles and the gases, CO2 and exhausted air, leave the tower 20 via a conduit 23.
The CO2 and exhausted air removed from tower 20 via conduit 23 may be supplied to the atmosphere in the greenhouse, thus constituting a saving on CO2 purchases by the grower.
The liquid leaving the tower 20 then passes through a second pH measuring device 24 before passing through a second mixer 25, again conveniently a "HYDRO-BRAKE", and the pH signals from the device 24 are transmitted to a control unit 26 which, in response to the signals received from device 24, controls the supply of acid (again HNO3) to the water inlet of mixer 25.
From mixer 25 the liquid passes to a nutrient charging unit 27, conveniently the well known "VOCOM" unit, where the required nutrients are added to the liquid before the liquid passes to the greenhouse, generally indicated by numeral 28, for release into the mats 29 supporting the root systems for the plants P.
The liquid exhausted from the greenhouse 27 is passed through a filter 30 to remove particulates therefrom and the high CO2, low oxygen liquid leaving filter 30 via a conduit 31 is passed through a sterilizer 32.
With such an arrangement the amount of acid supplied via supply 15 to the water entering the mixer 16 is preferably slightly less than that required to neutralize all the bicarbonates in the raw water and, conveniently, the acid supplied may be between 90% and 95% of the acid required.
By this means the liquid can have the major part of its bicarbonates properly neutralized and the resultant CO2 removed without the pH falling to the undesirable levels and, by the second monitoring of pH at 24 with only very small amounts of acid being necessary to neutralize the residual bicarbonates, a most accurate control of the pH can be obtained, to the benefit of the crop.
Further, and as stated hereinbefore, the removal of the CO2 gas by a relatively small volume of air in the tower 20 ensures a liquid supply to the plants which is high in oxygen and low in carbon dioxide, to the advantage of the crop.
Further, the exhaust liquid from the sterilizer unit 32, low in oxygen and possibly high in CO2 absorbed from the CO2 atmosphere in the greenhouse, can be recirculated by simply passing said exhaust water to the inlet end of vibration duct 17, wherein the vibrations induced in the water will drive CO2 out of solution for removal by air flows in tower 20 whereupon the CO2depleted, oxygen-enriched liquid can be passed to the VOCOM unit 27 for nutrient enrichment.
With such a recirculation system the "raw water" treatment, from meter 12 to mixer 16, may be used simply to process the raw water supplementing the recycled water.
The oxygen levels in the hydroponic solution may be further increased by the introduction of a soluble non-phytotoxic peroxide, such as urea peroxide, which will provide freely available oxygen and plant nutrient to the solution.
Commonly, sodium borate is supplied to the hydroponic solution to provide trace levels of boron. By supplying sodium perborate to the solution both oxygen and boron will be' made available to the plant roots.
It will be seen that the present invention when applied to the treatment of liquid for hydroponic feed liquid offers a number of economic and environmental advantages not found in the prior apart modes of liquid treatment.
CLAlh/ls 1. A method for treating a liquid comprising the steps of continuously passing the raw liquid through a monitoring station arranged to monitor a condition of the liquid, continuously supplying an additive to the liquid downstream of the monitoring station in direct dependance upon the monitored condition of the liquid and continuously passing the liquid/additive combination
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (22)
1. A method for treating a liquid comprising the steps of continuously passing the raw liquid through a monitoring station arranged to monitor a condition of the liquid, continuously supplying an additive to the liquid downstream of the monitoring station in direct dependance upon the monitored condition of the liquid and continuously passing the liquid/additive combination
through a mixer station to obtain an intimate dispersion of the additive through the liquid.
2. A method as claimed in claim 1., for treating a liquid to remove solid particles in dispersion in the liquid, including the steps of monitoring the solids contents of the liquid passing through said monitoring station and supplying an additive comprising a flocculating agent to the liquid, in dependance upon the monitored solids content of the liquid.
3. A method as claimed in claim 1., for softening water, comprising the steps of monitoring the pH of the water. passing through said monitoring station and supplying an additive in the form of an acid, selected to neutralize the bicarbonate content of the water, in dependance upon the monitored pH of the water.
4. A method as claimed in claim 1, 2, or 3 including the steps of passing the liquid and additive combination through a vibration zone and vibrating said liquid/additive mixture.
5. A method as claimed in 1, 2, 3, or 4, including the steps of passing a gas in the form of discrete bubbles through said liquid/additive mixture.
6. A method as claimed in claim 5, including the steps of selecting the gas to effect a chemical reaction with liquid/additive mixture.
7. A method as claimed in any preceding claim, for the hydroponic feeding of plants, comprising the steps of passing raw water through a pH monitoring station, continuously monitoring the pH of the water passing through said station, continuously supplying a nitric acid to the water downstream of said pH monitoring station in direct dependance upon the monitored pH condition, passing the water and acid mixture through a mixer station to intimately mix the said water and acid, and bubbling oxygen through the mixture to remove CO2 from said mixture, and subsequently adding nutrients to the treated water.
8. A method as claimed in any preceding claim including the step of sterilizing the liquid or the liquid/additive mixture.
9. A method as claimed in claim 8 including the step of effecting sterilization of the liquid or liquid additive by ultra violet radation.
10. Apparatus, for performing the method set forth in any one of claims 1 to 9 inclusive, comprising a flow duct for a liquid, monitoring means for monitoring a condition of the liquid flow at a fixed location along said flow path, means for supplying an additive to said liquid flow path downstream of said monitoring means, control means for controlling the supply of additive to said flow path upon the monitored condition of the liquid and means for mixing said liquid and said additive.
11. Apparatus as claimed in claim 10 in which said monitoring means comprise a light source and a light sensitive device spaced apart across the flow path.
12. Apparatus as claimed in claim 10 in which said monitoring means comprise a pH monitoring device.
13. Apparatus as claimed in claim 10, 11 or 12 in which the means supplying additives to the liquid flow path comprises a reservoir of additive and a metering pump.
14. Apparatus as claimed in claim 13 in which the control means for controlling the supply of additive is conveniently an electronics device, arranged to receive signals from the monitoring means and arranged to drive the metering pump in dependance upon the signals received from the monitoring means.
15. Apparatus a's claimed in claim 10, 11, 12, 13, or 14 in which said means for mixing said liquid and said additive comprise a hydro brake mixer.
16. Apparatus as claimed in any one of claims 10 to 15 inclusive including means for agitating the mixed liquid/additive combination.
17. Apparatus as claimed in claim 16 in which said means for agitating the mixed liquid/additive combination comprise vibrating means,
18. Apparatus as claimed in claim 17 in which the mixed liquid/additive combination flows along an open channel and part of the vibrating means extend into the liquid flow along said channel.
19. Apparatus as claimed in claim 16, 17 or 18 in which the mixed liquid/additive combination is caused to flow through a tower.
20. Apparatus as claimed in claim 19 in which the liquid/additive combination is passed through spray means in the upper regions of the tower to fall in droplets down the tower.
21. A method for treating liquid substantially as hereinbefore described.
22. Apparatus for treating a liquid substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868614530A GB8614530D0 (en) | 1986-06-14 | 1986-06-14 | Liquid treatment process |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8713923D0 GB8713923D0 (en) | 1987-07-22 |
| GB2192875A true GB2192875A (en) | 1988-01-27 |
| GB2192875B GB2192875B (en) | 1990-05-16 |
Family
ID=10599476
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868614530A Pending GB8614530D0 (en) | 1986-06-14 | 1986-06-14 | Liquid treatment process |
| GB8713923A Expired - Fee Related GB2192875B (en) | 1986-06-14 | 1987-06-15 | Improvements in or relating to liquid treatment processes |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868614530A Pending GB8614530D0 (en) | 1986-06-14 | 1986-06-14 | Liquid treatment process |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8614530D0 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0402464A1 (en) * | 1988-02-10 | 1990-12-19 | Kabushiki Kaisha Komatsu Seisakusho | Solution culture apparatus |
| NL9002723A (en) * | 1989-12-12 | 1991-07-01 | Toshiba Kk | SYSTEM FOR CONTROLLING A FOOD SOLUTION IN A WATER CULTURE. |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1292933A (en) * | 1969-02-24 | 1972-10-18 | Martin Marietta Corp | Method and apparatus for purifying a natural body of water |
| US4181951A (en) * | 1978-04-28 | 1980-01-01 | Jan Boeke | In-line pH and pIon controller |
| EP0076683A1 (en) * | 1981-10-05 | 1983-04-13 | Exxon Research And Engineering Company | Apparatus and method for controlling the pH of a continuous process stream |
| US4544489A (en) * | 1984-07-02 | 1985-10-01 | Canadian Patents And Development Limited | Process and apparatus for controlled addition of conditioning material to sewage sludge |
-
1986
- 1986-06-14 GB GB868614530A patent/GB8614530D0/en active Pending
-
1987
- 1987-06-15 GB GB8713923A patent/GB2192875B/en not_active Expired - Fee Related
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1292933A (en) * | 1969-02-24 | 1972-10-18 | Martin Marietta Corp | Method and apparatus for purifying a natural body of water |
| US4181951A (en) * | 1978-04-28 | 1980-01-01 | Jan Boeke | In-line pH and pIon controller |
| EP0076683A1 (en) * | 1981-10-05 | 1983-04-13 | Exxon Research And Engineering Company | Apparatus and method for controlling the pH of a continuous process stream |
| US4544489A (en) * | 1984-07-02 | 1985-10-01 | Canadian Patents And Development Limited | Process and apparatus for controlled addition of conditioning material to sewage sludge |
Non-Patent Citations (1)
| Title |
|---|
| DIET 2, J: NOLL,W. ND2. NEUE DELIWA-Z.; (82)P407-8 VOL 33 NO 11. * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0402464A1 (en) * | 1988-02-10 | 1990-12-19 | Kabushiki Kaisha Komatsu Seisakusho | Solution culture apparatus |
| EP0402464A4 (en) * | 1988-02-10 | 1991-05-08 | Kabushiki Kaisha Komatsu Seisakusho | Solution culture apparatus |
| US5212906A (en) * | 1988-02-10 | 1993-05-25 | Noboru Okuno | Liquid culture apparatus |
| NL9002723A (en) * | 1989-12-12 | 1991-07-01 | Toshiba Kk | SYSTEM FOR CONTROLLING A FOOD SOLUTION IN A WATER CULTURE. |
| US5590490A (en) * | 1989-12-12 | 1997-01-07 | Kabushiki Kaisha Toshiba | Hydroponic nutrient solution control system |
| US5598663A (en) * | 1989-12-12 | 1997-02-04 | Kabushiki Kaisha Toshiba | Hydroponic nutrient solution control system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8614530D0 (en) | 1986-07-23 |
| GB2192875B (en) | 1990-05-16 |
| GB8713923D0 (en) | 1987-07-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732E | Amendments to the register in respect of changes of name or changes affecting rights (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19970615 |