ZA200400839B

ZA200400839B - Method and device for disinfecting water.

Info

Publication number: ZA200400839B
Application number: ZA200400839A
Authority: ZA
Inventors: Karl-Johann Klein
Original assignee: Klein Karl Johann
Priority date: 2001-07-24
Filing date: 2004-02-02
Publication date: 2005-02-02
Also published as: EP1409417A1; WO2003010095A1; DE10136014A1

Description

ERS SEER E Se -2004/0839 _

SMB oo oo : : Method and Device for Disinfecting Water ~~. The present invention relates to a method for the continuous disinfection of water iE including drinking, bathing and industrial water, comprising a filtration step, a

RE short-term disinfection step and a long-term disinfection step with the addition of BN precious metal ions. The invention further relates to a device suitable for such a ~~ method. -. oo

Co The availability of hygienically safe drinking water is a serious problem mainly in oo developing countries and third world countries. In many cases, it is necessary to

Co | process the water in order to obtain safe water. To render the water germ-free, it

ERE | is usually first freed from turbid matter. Thus, so-called flocculants can be added to wo the ‘water ‘to achieve a better segregation in the subsequent processing steps oo oo (sedimentation/flotation + filtration). | SRE oo

R oo After the removal of turbid matter, the water can be disinfected. The disinfectant which is employed most often by far still today is chlorine (chlorine bleach, chlorine : } gas). A disadvantage of these methods is the health hazard from excess additions - or from the formation of trihalomethanes. A further problem in third world coun- tries may be the provision of chlorine. Further, ultraviolet irradiation is employed : for disinfection. An advantage of this method is the fact that no substances are "dosed into the water. A disadvantage is the fact that this method does not achieve . a depot effect of disinfection like with chlorine addition. Problems arise in tubing systems or in storage tanks if the hygienic conditions are not optimum. A further method involves the addition of silver or copper ions for disinfecting water (oli- - godynamic effect), which also has a depot effect.

A combination of ultraviolet irradiation and the addition of silver ions has been . described in JP 9187773. For the cleaning of water, an apparatus is used compris- ing a filter, a device which produces silver ions and an ultraviolet sterilization - _ device, wherein said silver-ion producing device is provided upstream from said ultraviolet sterilization device. In this apparatus, the water is circulated, i.e., the oo apparatus is employed only for the processing of water having a low degree of ‘contamination (such as storage tanks and aquariums). On the other hand, this means that this apparatus cannot be employed for a continuous disinfection method, especially when heavily loaded water is to be cleaned, since a primary = disinfection by means of silver ions as described in JP 9187773 has the drawback R that fairly high silver ion concentrations are required. Thus, the silver ion concen- : Ba tration in water may exceed the limit value, which may lead ‘to health problems - upon permanent intake. Further, this arrangement involves a risk that disinfection “does not occur immediately, but only after a delay of up to several hours, or that . ~~ disinfection is Act ensured for high germ numbers. | | . ] : | - ‘From IP 06114393, a circulation system for cleaning a pond (i.e., killing of algae) : ~~ has been known. Thus, the water is withdrawn from the pond, treated with oo ultraviolet radiation in a device provided outside the pond, subsequently added ~ with silver or copper ions to suppress the formation of algae, and recirculated into the pond. The quality of the pond water is monitored by means of a conductivity or Co turbidity measuring device. An effective cleaning of “highly Coritaminated water, © : ‘especially having a high content of turbid matter, is not possible with the method EE : described here. | -

JP 60178490 describes a method for the cleaning of water. Copper, which serves as a flocculant, is supplied to the water electrochemically. A sufficient disinfection of the water did not occur. :

It was the object of the present invention to develop a method and a device which do not have the drawbacks of the above mentioned prior art. The processing of the water should be done, if possible, without consumption materials, e.g., fuel or chemicals, so that the method is free of maintenance, if possible. Further, an installation for such a method which is also suitable for being used in developing countries was to be developed.

CL : Summary of the invention “A new method suitable for continuous disinfection has now been developed which

Co is a combination of flocculation, filtration (including flocculation), ultraviolet ~~

E | disinfection and disinfection with silver and/or copper ions. Also, a suitable device ~~

CL for this method has been developed. Thus, the present invention relates to

So (1) a method for the continuous disinfection and preservation of water, comprising: oo ~~ the following successive steps: | | nN oo (a) mechanical filtering of the starting water; : - : (b) short-term disinfection of the filtered water; and : y (c) long-term disinfection of the water obtained in step (b) by adding precious =

PR metal ions; and : Co Lo ) (2) a device for the continuous disinfection and preservation of water, comprising a filter means for filtering the starting water, a short-term disinfection means downstream from said filter means for the short-term disinfection of the filtered water, a long-term disinfection means downstream from said short-term disinfec- tion means, a transport means for transporting the water through said filter means, short-term and long-term disinfection means, and a network-independent power supply means. oo An essential aspect of the device (2) is the fact that the power supply means for supplying the short-term and/or long-term disinfection means and/or the transport means, which may be a pump, for example, may be network-independent. Such a power supply means, such as a solar module and/or a wind energy plant, are © suitable for producing power independent of a power network. Thus, it is possible to employ the device according to the invention in developing countries, in al particular. This is possible, in particular, due to the simple low-maintenance design : of the device. : To be able to process water, which is to have drinking water quality, for example, "by means of a network-independent power supply means, a control means is preferably provided. The individual members of the device according to the invention, i.e., those which must be supplied with energy, are supplied with energy : by the control means in accordance with the water flow rate. Due to this aspect, } -. which is essential to this particularly preferred embodiment of the invention, itis ensured that sufficient energy is available, for example, for the short-term and/or oo long-term disinfection means, to enable the desired disinfection or processing of 0 the water. It is to be considered that the energy supply may strongly vary due to “the network-independence of the power supply means. If the transport means for =~ transporting the water is a pump, the flow rate will also vary due to the variation So of the energy supply. When a pump is provided as the transport means, the : ~~ revolutions per minute of the pump can be immediately detected, and the water

EE "© flow rate established on the basis of the revolutions: per minute of the pump. The Co pump may be an electrically driven pump, or else a pump driven by wind energy. | oo : Further, it is possible to establish the water flow rate by means of a flow sensor. an . In a preferred embodiment of the device (2), a flocculant adding means, which

SE may optionally have a reactor for flocculation, is provided upstream from the filter

BN means in which contaminants are filtered from the water. The addition of floccu- ) lants, such as mineral salts, causes flocculation of the particles contained in the

B water, so that these can be filtered out more easily and effectively in the filter means. According to the invention, it is particularly preferred to provide metal electrodes, connected with said power supply means, as flocculant addition means. ' These are preferably copper electrodes provided in the water flow. By applying a current to the copper electrodes, copper ions which serve as flocculants are produced by electrolytically dissolving the copper electrode. Such a flocculant addition means has the advantage that the quantity of flocculant, i.e., the quantity of ions supplied, can be easily controlled since the ion supply is directly dependent on the electric current. Thus, it is possible to supply an electric current to the electrodes which has been established as a function of the flow rate. i.

. . B . _ 5 _ - : :

Preferably, as said long-term disinfection means, there are also provided metal electrodes, preferably silver electrodes, which are also positioned within the water.

Thus, long-term disinfection is effected by the addition of silver ions or other a oo suitable metal ions. The electrodes can be easily controlled as a function of the ~~. water flow rate, so that an overdose or deficiency of silver ions is avoided.

Thus, in the preferred embodiment of the invention, the amount of copper ions oe supplied as a flocculant and the amount of silver ions supplied for long-term - disinfection can be easily controlled as a function of the flow rate. The flow rate in ~~~ turn essentially depends on the transport capacity of the pump, which may be g selectable, for example, when a network connection is provided, or depends on the solar and/or wind intensity. oo : ~ Preferably, the control means is additionally connected with a turbidity measuring

Bn means, such as an ultraviolet or light transmission measuring means. By the: . turbidity measuring means, the degree of turbidity of the starting water can be determined. Depending on the degree of turbidity, the control means then controls oo ~ the quantity of flocculant added. Preferably, the controlling of the energy supply to

BE . the electrodes in the flocculant addition means is effected in accordance with the Co ~~ degree of contamination and the water flow rate. : : oo an ~~... .. .. Brief description of the Figures. . Co a

Figure 1 shows a schematic view of a preferred embodiment of the invention; and : Figure 2 shows a schematic view of a preferred embodiment of a combined short- and long-term disinfection device.

Detailed description of the invention "In the method (1) according to the invention, the starting water is first filtered, : “and after filtration, a short-term disinfection step is performed, for example, by an ultraviolet disinfection system, to achieve immediate disinfection.

EE | oo -6-

If required by the amount of turbid matter, the filtration step may be supported by adding a flocculant. In such a mode of process operation, removal of the turbid matter is effected after the addition of the flocculant by subsequent mechanical filtering. The preferred flocculants are copper ions, such as copper hydroxide, which are produced by an electrophysical process (i.e., electrolytic dissolution of - soluble copper electrodes) in a particularly preferred embodiment of the invention. oo Alternatively, they may also be added to the water by supplying an aqueous ~~ solution of a copper or silver salt. An advantage of the electrophysical process is : the fact that the balance of the water (salt content, pH value) is not changed. In addition, no chemicals need be provided, or only a lower amount thereof. Other - a suitable flocculants include iron and aluminum salts, for example, ferric chloride, : aluminum sulfate and poly(aluminum chloride).

Co ~The amount of flocculant added is from 0.3 to 3.0 mg/l, preferably from 0.5t0 0.7

So : } mg/l, of water to be processed, depending on the degree of contamination.

A preferred short-term disinfection method is ultraviolet treatment, wherein oo preferably: So . - - the ultraviolet treatment is effected by irradiation with a wavelength of from 250 : to 280 nm, preferably ata wavelength of 254 nm, and/or | CL . EE the water is exposed to an irradiation dose of at least 250 J/m?, preferably at least 350 J/m?, more preferably at least 400 jymi oo

To achieve a depot effect of disinfection, the water is subjected to long-term disinfection by adding heavy metals, e.g., copper and/or silver ions. Due to the disinfection of the water with ultraviolet rays, the silver and copper dose can be reduced to a minimum since the dosage of the silver and copper ions only serves for preserving the water. Preferably, the concentration of copper and/or silver ions in the processed water is lower than 100 pg/l or lower than 10 ug/l. Thus, the values of the legal EU regulations for the maximum copper and silver content in water are fallen below. However, preferred are substantially lower concentrations of copper and silver ions for ensuring the bacteriostasis of the processed water,

’ _ 7 _ Co | - namely from 0.3 to 3.0 ppm, preferably from 0.5 to 0.7 ppm, of Cu®*, and/or from + 1to 50 ppb, preferably from 1 to 10 ppb, of Ag*. oo :

In a preferred embodiment of the method (1), the dosing of copper/silver ions according to step (c) is effected together with the ultraviolet irradiation according to step (b) in one reactor. | EE oo The method (1) according to the invention enables a "continuous process opera-

E tion", i.e., it is not necessary to circulate the water to be processed. Depending on ~~ the quality of the water, different or differently designed process steps are applied . oo : in which the degree of contamination is accounted for. Thus, with the method Ce . ) “according to the invention, it is possible to treat and disinfect surface, well,

SE - industrial and swimming pool water, and to preserve it for an extended period of y time, i.e., for 24 to 48 h, in a single reaction cycle of steps (a) to (c). - i : on To be able to reliably disinfect the water, it must be free from solids. Therefore, Co the device (2) according to the invention preferably has a flocculant supply means - 10, a filter means 12, a short-term disinfection .means 14 in the form of an : oo : ultraviolet irradiation means, and a long-term disinfection means 16. From a pump - : Lr 18, water to be processed is pumped through a tubing 20 in the direction of an =~

SI arrow 22. For driving the electric pump 18, it is electrically connected through a } . line 26 with a solar module 24 having one or more solar cells: The volume con- - veyed by the pump 18 depends on the amount of energy produced by the solar : ~~ module 26. It is to be considered that other elements of the device according to = the invention also require energy, so that a reduced amount of energy is available : to the pump for transporting water. In other words, the energy produced by the’ solar modules 24 must be sufficient for all the means of the device according to the invention which require an energy supply. Through a control means 28 and/or 49, it can be controlled, for example, that from the energy available, the energy supply of the flocculant addition means 10, the short-term dosing means 14 and : the long-term dosing means 16 is ensured first. Preferably, the flocculant addition ‘means 10, the short-term dosing means 14 and the long-term dosing means 16 ~~ have their own ‘energy supply means, e.g., their own solar cells. These are

. . | © 8 _ ’ } designed and/or switched in a way that sufficient energy is available for these means when the pump is started. : : In the Example shown (Figure 1), the flocculant addition means involves copper ions, which must also be supplied with electric current. The current supplied to the copper ions depends on the water flow rate. The flow rate is detected by the control means 28. This may be done, for example, by a flow meter 30 which measures the flow rate of water to be treated in the tubing 20. Alternatively, the ~~ flow rate may also be sensed at the pump 18 by means of a rotational speed. : sensor 32. Based on the flow rate, the control means 28 determines the current So strength which is to be supplied to the copper electrodes of the flocculant addition means 10 via a line 35. oo oo -

In addition, for determining the required amount of flocculant, i.e., the required . - amount of copper ions, the turbidity of the water to be treated, which is trans- ported by the pump 18 in the direction towards the flocculant addition means 10, - can be determined. Thus, a turbidity measuring means 34 is provided which } determines the turbidity of the water, for example, by means of a light and/or : ultraviolet transmission measurement. Based on this measuring value, the current a. strength supplied to the flocculant addition means 10 through the line 35.can be : increased or reduced. The turbidity of the water may also be established by a conductivity test. Thus, the turbidity measuring means-34 may effect a light and/or -

Co ultraviolet transmission measurement and/or a conductivity measurement.

The water supplied with flocculant is then transported to the filter means 12 through a tubing 36. In the filter means, there are provided, for example, several fine-meshed sieves and/or a filter with packings such as sand packings or the like. ‘These may be arranged, for example, in a stepwise fashion, so that the sieves become finer and finer in the direction of flow.

Subsequently, the filtered water is transported to the short-term disinfection means 14 through a tubing 38. In the Example shown, an ultraviolet irradiation means is provided as the short-term disinfection means 14. This is an irradiation means having an ultraviolet lamp or some other source of ultraviolet radiation. By B

Claims

oo | CLAIMS: Co (amended October 16, 2003)

‘1. A method for the continuous disinfection and preservation of water, com- prising the following successive steps: : : CL - (a) addition of a flocculant to the starting water followed by mechanical - filtering; : oo EE oo : (b) short-term disinfection of the fittered water by ultraviolet treatment; and | ) ET | (c). long-term: disinfection of the ‘water obtained instep (b) by adding

~~... precious metal fons. B a EE

2. ~The method according to claim 1, wherein said flocculant comprises copper CL C3. The method according to claim 2, wherein the addition of said copper ions is . effected by an electrophysical process, especially an electrolytic process. IEE

7 4. “The method according to claim 2 or 3, wherein the amount of copper ions oo SE added for flocculation is from 0.3 to 3.0 mg per liter of water, preferably ~~ : oo from 0.5t0 0.7 mg per liter of starting water. Co } 5, The method according to one or more of claims 1 to 4, “wherein said - ultraviolet irradiation in step (b) is effected by: ~~ - irradiation with a wavelength of from 250 to 280 nm, preferably at a : wavelength of 254 nm, and/or Co

Co . - the water is exposed to an irradiation dose of at least 250 im? preferably =~ atleast 350 J/m?, more preferably at least 400 J/m?. oo | AMENDED SHEET

- | . oo 6. The method according to one or more of claims 1 to 5, wherein said : precious metal ions added in step (c) are copper and/or silver ions which are Co added to the water, in particular, by an ele¢trophysical process. oo SE 7. ‘The method according to claim 6, wherein the water has a concentration of To oo ‘copper and/or silver ions of lower than 100 pg/! of copper ions and/or lower RE than 10 ug/l of silver ions, preferably from 0.5 to 0.7 ppm of copper ions EEE and/or from 1 to 10 ppb of silver ions, after said disinfection step (c): Lo - 8. The method according to one or more of claims 1 to 7, wherein said dosing Lo ERT ~ of copper/silver ions according to step (c) is effected together with the ul- I : " traviolet irradiation according to step (b) in one reactor. co i TE - - 9. } The method according to one or more of claims 1 to 8, which is not operated }

J. in a recirculated mode and which is ‘suitable, in particular, for the disinfec- = - “© tion and preservation of surface, well, bathing and industrial water. . : oo - "10. . ‘The method according to one or more of claims 1 to 9, wherein all process. SE CL ] RE "steps are operated with direct current, and preferably solar cells or wind en- : N Sa ergy serve as the power source. ~~ SE oo Co 11. © The method according to any of claims. 1 to 10, wherein the amount. of

~~. copper ions for flocculating the water and/or the amount of silver ions for Ce disinfection is changed as a function of transport capacity. i © 12. The method according to any of claims 1 to 10, wherein the addition of the E copper ions is controlled as a function of water quality and/or transport ca- pacity.

13. A device for the continuous disinfection and preservation of water, compris- ing: = oo ) a filter means (12) for filtering the starting water; AMENDED SHEET a short-term disinfection means (14) comprising an ultraviolet irradiation ~ means downstream from said filter means (12) for disinfecting the filtered water; oo oT oo a long-term disinfection means (16) downstream from said short-term ’ Co LT disinfection means (14); : 0 So ~~ a transport means (18) for transporting the water through said filter means = -- EEE (12), short-term (14) and long-term disinfection means (16); and oo CT SN ‘a power supply means (24) for power-supplying said short-term disinfection : © = means (14) and/or said long-term disinfection means (16) and/or said ©. CC temsportmeans@®.

14. The devicé according to claim 13, characterized by a flocculant addition Coe

©... means (10) upstream from said filter means (12). ~~ SE BEATE : 15. The device according to claim 13 or 14, characterized by a control means oo E . . . (28) for controlling said long-term disinfection means (16) and/or said floc- a oo Lo ""culant addition means (10) as a function of the water flow rate. ER

16. The device according to claim 15, characterized in.that said transport means Ce (18) is a pump connected with said power supply means (24), and said con- _ trol means (28) is connected with the pump for detecting the revolutions ~~ + per minute of the pump. oo oo

17. The device according to claim 15 or 16, characterized in that said control means (28) is connected with a flow sensor (30) for establishing the water - flow rate. © 18. The device according to any of claims 14 to 17, characterized in that said : “flocculant addition means (10) has metal electrodes, especially copper elec- © trodes, connected with said power supply means (24) for producing metal a © ons as flocculants. oo oo . | AMENDED SHEET

. TL : . = 4 = © 19. The device according to claim 18, characterized in that said control means (28) is connected with said metal electrodes and controls the energy supply oo as a function of the water flow rate. : : Co 20. The device according to any of claims 15 to 19, characterized in that said : ‘long-term disinfection means (16) has metal electrodes, especially silver Co "electrodes, connected with said power supply means (24) for producing ions

~~. forlong-term disinfection. oo

©. =21. The device according to claim 20, characterized in that said control means RR | (49) is connected with said metal electrodes (61) and controls the energy - | ) E : ‘supply as a function of the water flow rate. © | : : C22. The device according to ‘any of claims 15 to 21, characterized in that said : CL control means (28) is connected with a turbidity and/or ultraviolet transmis- } sion measuring means (34) and controls said flocculant addition means (10) LT as a function of the degree of turbidity and/or the ultraviolet transmission of : Co Co I. ‘the water. _ . oo a ; oe 23. The device according to any of claims 13 to 22, characterized in that said =~ EE Co short-term disinfection means (14) has an ultraviolet irradiation means (58) . Se provided within a flow reactor (52), and said metal electrodes (61) of said ~~ ~~ long-term disinfection means (16) are provided within said flow reactor - 24. ‘The device according to any of claims 13 to 23, characterized in that an CS ultraviolet transmission measuring means 40 is provided ‘downstream from CL said filter means (12) for monitoring the filtering effect. AMENDED SHEET