CA2470869A1 - Water softener and purifier - Google Patents

Abstract

In various aspects, this invention provides a method or device for the permanent removal of scale producing hardness from water using electrochemical or electromagnetic means to precipitate a portion of the hardness followed by membrane filtration of the resulting particles as well as other organic and inorganic particles, protozoa, cysts, bacteria and virus. No chemical addition is required in the process to produce a chemically soft, clean pure water. The invention would compete with conventional water softening which may utilize one or more of prefiltration, chemical precipitation, chemical sequestration, ion-exchange, electrodeionization, nanofiltration or reverse osmosis. A device using the method may be designed to treat water in household and small commercial water applications.

Description

Title: Water Softener and Purifier >=field of the invention X0001] The invention relates to water conditioning, softening or purification, More particularly, the invention relates to the removal of hardness from water, electrochemical or electromagnetic precipitation, or membrane filtration.
Backs~round of the invention [0002 Formation of scats by waters containing calcium and magnesium hardness is a significant problem in household, commercial and industrial operations.
[0003] Various attempts have been made to reduce scale-causing hardness in water by electrolytic means. Some of these attempts are described in EP 0 171 357; lJS 6,258,250; and, US 5,951,856.
[D004~] An ultrafiltration method and device for water purificafion is disclosed in US 6,589,26 ~20Q3), The device is a hallow fibre microfiltrationlultrafiltration module which uses in line pressure to permeate water through the membranes and has means to clean the membranes by backflushing periodically. US 6,589,x.26 is incorporated herein in full by this reference to it.
Surnmary of the invention [UQ06] It is an object of the invention to provide an apparatus or process for removing hardness or solids from water_ [0006] in various aspects, this invention provides a method or device for the permanent removal of scale producing hardness from water using electrochemical or electromagnetic means to precipitate a portion of the z5 hardness followed by membrane filtration of the resulting particles as well as other organic and inorganic particles, protozoa, cysts, bacteria anti virus.
No chemical addition is required in the process to produce a chemically soft, clean pure water. The invention would compete with conventional water softening which may utilize one or mare of prefiltration, chemical precipitation, - Z -chemical sequestration, ion-exchange, eiectrodeionlzation, nanofiitration or reverse osmosis. A device using the method may be designed to treat water in household and small commercial water applications.
[Ofl07] )n one aspect, this invention permanently removes calcium and magnesium hardness in water by an electrolytic or electromagnetic precipitation process followed by ultrafltration. The process does not require the aid of added chemicals to produce effective results.
[0008) In one aspect, this invention treats a flowing water stream by electrolytic or electromagnetic means to produce a precipitate with a size 70 retainable by MF, OF or NF membrane filters.
j0409] In one aspect, this invention removes calcium and magnesium precipitate from the water immediately after electrolytic or electromagnetic formation using a MF, OF or NF membrane fiber filter.
[00'lU] In one aspect, this invention removes from the water stream any organic or inorganic particulate matker, protozoa, cysts, bacteria and virus with the same MF, OF or NF membrane fiber filter.
[0011] In one aspect, this invention periodically on-line cleans both the electrolytic or electromagnetic cell and membrane fitter by flushing bath unifis strnultaneously at high velocities and backflushing the membrane fiber fitter.
[OD~Iz~ In one aspect, this invention provides a system which contains the above elements; specifically, a flow-through electrolytic or electrochemical precipitation chamber followed immediately by an inline MF, OF or NF
membrane fiber filter. The system may also have means for flushing the feed side of the precipitation chamber or membrane flter_ "his system may be sized specifically for household and small commercial use, [0013] In one aspect, this invention provide$ a method and system of reducing calcium and magnesium hardness in water without the necessary addition of chemicals using electrolytic or electromagnetic precipitation followed immediately by MF, OF or NF membrane ~Itration.

~001~4, The summary above is intended to introduce the reader to the invention which may reside in a combination or sub-combination of steps or elements discussed shove or in other parts of this patent.
Brief description of the drlWInQS
[0011 Embodiments of the invention will be described belouv with reference to the following figures:
jOt?16] Figure 1 is a t~iock diagram a system using an electrolytic cell and a OF membrane filter.
ja01?] Figure 2 is a block diagram a System using an electromagnetic 90 cell and a MF membrane filter.
Description of Embadimen~s [0018, The following is a general description of process steps and apparatus elements which apply to two specific ernbodirnents of the invention that are described furf:her below.
[OD19] In an electrolytic precipitation process water is introduced into a flow-thraw;rgh electrolysis cell having two or more electrodes where a periodically reversing DG or AC current is applied to the efeGtrodes_ ~i1o20~ Calcium and magnesium precipitation is effected as oxide, hydroxide andlor carbonate an the non-conductive media in the immediate 2Q vicinity of the electrodes. Other metal ions may be likewise precipitated.
Water velocity, current magnitude and reversal times are adjusted tp allow the precipitates to grow in size to greater than 0_02 um.
jd021~ i'eriodically the current flowing through the electrodes is reversed; i_e., anode becomes cathode and cathode becomes anode. This repels the formed calcium and magnesium precipitates from the electrode region into the flowing bulk water. Once out of the precipitation zone, the precipitates eventually revert back to the dissotved ionic farm.
[022? An electrolysis cell consists of an elongated flow-through chamber containing two ar mare electrodes of non-reactive conducting -4_ material. Between the electrodes is a porous non-ennductive material or a granular material which can contain both conductive and non-conductive components.
[OQ23j Initially one electrode is designated as the anode and the other h as cathode. The auxiliary electrodes can be of either polarity.
[0024] DC current from a switching source is applied to the electrodes during operation. The current is periodically switched in polarity. The farmer anodes become cathodes and vice versa. The period duration and the current magnitude are adjusted to allow precipitate growths to filterable size. An AC
current source may also be used but is not preferred.
ZOa25] 1n an electromagnetic precipitation process the precipitation chamber contains or is surrounded by. one ar more electrically conductive coils which induce a magnetic field in the flow-through precipitation zone.
This magnetic field is controlled by a current source which may produce a constant 1~ DC, intermittent bC, reversing DC or AC to the coil(s). in the case of constant magnetic field, permanent magnets may be substituted for the current source and coit(s).
T002B] The magnetic fields cause temporary instability in the ionic distribution of the water t7owlng through the electromagnetic cell, causing 2U calcium and magnesium to precipitate as oxides, hydroxides or carbonates in a microcrystalline form. Other metal lon5 may be likewise precipitated.
Outside of this zone the precipitates eventually hydrolyze back to the ionic state.
[0027] An electromagnetic cell consists of a cylindrical chamber 25 containing car surrounded by one or more electrically conductive coils.
These coils) are connected electrically to a current source. The current may be constant DC, intermittent DC, reversing DC car AC try generate the magnetic filed inside the flow~through cell. If a constant magnetic filed i$ required, permanent magnets may be substituted for the current source and coil(s).

[Ota28] A system may consist of two sub-units; the electrolytic ar electromagnetic cell and the MFIUF/NF membrane filter unit. The membrane filtration unit is tightly coupled to the electrolytic or electromagnetic veil. The system may have a modular design with a replaceable electrolytic or electromagnetic cell and a replaceable membrane filter module.
[0029] Water leaving the precipitation zone of the electrolysis or electromagnetic cell is immediately filtered, after flowing through a short path and interval time, lay an MF1UFINF membrane filter to remove the precipitate.
~OD30] The MFJUFINF membrane filter running as a dead-end filter separates the calcium and magnesium precipitate, permanently removing the hardness as well as any other inorganic or organic particulate matter, algae, protozoa, cysts, bacteria and virus from the water. The MFIUFINF membrane filter unit may consist of a hallow fiber filtration module ar a spirally wound flat sheet module. The system may also have a pneumatic accumulator on the ib permeate stream and a drain valve on the concentrate stream- The drain valve may be automated. 'The module has an inlet for, the feed, an outlet for the permeate and a drain outlet far the concentrate.
[OD3lj Cleaning of the system is done on-line. The membrane fiber filter is periodically flushed with feed at elevated flow and may be simultaneously backflushed with permeate to flush retained particulates from the membrane surface and divert the particulate rich concentrate to drain. As a result of this action the feed flow also increases effectively flushing the electrolytic or electromagnetic cell with higher velocity, sweeping attached precipitates infi~o the bulk stream and out of the system to the drain.
l~ernoving the precipitate gives a permanent reduction in hardness- Multiple current reversal cycles during this time will effect greater cell cleaning. A timer or controller coordinates the periodic current reversals in the electrolytic cell and determines the cleaning cycle by control of the automated drain valve.
[0032] Referring to Figure 1, untreated feed water [~] enters the 3D electrolytic flow-through cell j2]. This cell contains two electrodes {3], one of which is an anode and the other is the cathode at any instance of time.

Around and between the electrodes is a non-conducting porous material or a granular material [4], a portion of which may be conductive. The electrodes are wired to an adjustable switching DC or AC current source [5]. The water flows through the cell [2] from the inlet [1j to the conduit [E?]_ In the cell the Ca and Mg ions are converted by the electrolytic current to an oxide, hydroxide andlor carbonate precipitate in the region of the electrodes. Other metal ions such as >=a and Mn may also he precipitated in this manner. The precipitate is swept by the flow c~f the water from the electrolysis cell into the membrane filter module [TJ through the conduit [0]. The precipitates along with other 14 metal precipitates, organic and inorganic particulates, algae, protozoa, cysts, bacteria and virus are separated by the membrane fibers and concentrated in the feed side [8] of the filtration module. Softened, purified water flows from the permeate charnlxer [9] of the membrane module through the product pipe [10] to the point of use. A pneumatic accumulator [11], such as a partially air filled pressure tank or a diaphragm tank, is connected to the product pipe close to the membrane filter module to provide pressurized water for backflushing.
X0033] To effect cleaning of both electrolytic cell and membrane filter module, the automafiic valve [13] attached to the concentrate outlet [12] of the membrane filter module is opened periodically to allow the concentrate chamber of the membrane filter module ['T] to flow to drain. This has the effect of lowering the pressure in the concentrate chamber. Consequently the feed flow is increased causing higher velocity flushing to drain of bath the electrolytic cell [2] and the concentrate side [8] of the membrane filtration module [7]. Treated water is also caused to flaw from the pneumatic accumulator [11] to the permeate chamber [9] and backwards through the membrane and then to drain, carrying with it materials reversibly flushed from the membrane feed side surtace. At the completion of the filush cleaning cycle the drain valve is closed and the system operates as previously described.
The flush cleaning cycle is controlled by a timer ar similar controller [not shown]. The timer or controller performs the flush cleaning cycle sufficiently often to prevent excessive re-dissolution of the precipitates.

_7_ ~OD34] Referring to Figure 2, untreated feed water [1] enters the electromagnetic flow-through cell [2a]. This cell contains or is surrounded by an electrically conductive coil [3a]. The coil is wired to an adjustable switching DC or AC current source j5]. The water flows through the cell [~a] from the inlet j1] through the induced electromagnetic field j4a] to the outlet [6]. In the cell the Ca and Mg ions are converted by the ion instabilities induced by the electromagnetic freld to an oxide, hydroxide andlor carbonate precipitate.
Other metal ions such as Fe and Mn may also be precipitated in this manner.
The precipitate is swept by the flaw of the water from the electromagnetic cell into the membrane filter module (7] through the outlet conduit [6]. The precipitates along with other metal precipitates, organic and inorganic particulates, algae, protozoa, cysts, bacteria and virus are separated by the membrane fibers and concentrated in the feed side ['8] of the filtration module.
Softened, purified water flows from the permeate chamber [9] of the membrane module through the product pipe [10] to the point of use. A
pneumatic accumulator ['11] is connected to the product pipe close to the membrane filter module try provide pressurized water for baclctlushing.
[0035a To effect cleaning of bath electromagnetic cell and membrane filter module, the automated valve [13] attach~i to the concentrate outlet j12]
2r~ of the membrane filter module is opened periodically to allow the concentrate chamber of the membrane fitter module to flow to drain. This has the effect of lowering the pressure in the concentrate chamber. Consequently the feed flow is increased causing higher velocity flushing to drain of both the electrolytic cell and the concentrate side of the membrane filtration module. Treated water is also caused to flow from the pneumatic accumulator [11] to the permeate chamber and backwards through the membrane and then to drain, carrying with it materials reversibly flushed from the membrane feed side surtace. At the completion of the flush cleaning cycle the drain valve is closed and the system operates as previously described. The flush cleaning cycle is 3D controlled by a timer or similar controller [not shown]_ The controller or timer may be configured to perform the flush cleaning cycle with sufficient frequency to provide acceptable levels of re-dissolution of precipitates. The duration of the filush clean oyvle may also be varied in relation to the volume of water that has passed through the system since the last flush cleaning cycle.
[~D03g1 lather alternate or modified embodiments may also be made within the scope Qf the invention_

Claims (9)

1. A method of permanently reducing water hardness and purifying the water using on-fine electrochemical precipitation of the Ca and Mg hardness followed immediately by membrane filtration.

2. The method of claim 1 wherein said electrochemical precipitation includes electrolytic, electromagnetic or magnetic means.

3. The method of claim 1 wherein said membrane filtration is MF, UF or NF.

4. The method of claim 1 wherein simultaneous cleaning of the electrochemical cell and membrane filter is effected by higher flow flushing and simultaneous backflow through the membrane filter.

5. A system comprising an in-line electrochemical precipitation module directly upstream of an in-line dead-end membrane filtration module

6. The system of claim 5 further comprising a pneumatic accumulator in fluid connection with the permeate side of the membrane module.

7. The system of claim B further comprising a valve operable to periodically connect the retentate side of the membrane module to a drain.

8. The system of claim 7 wherein an inlet to the precipitation module is connected to the water supply to a house or building, the outlet from the precipitation module is connected to the inlet of the membrane module and the outlet of the membrane module is connected directly to a network of pipes configured to carry water to valves operable by users to provide water at a point of use.

9. The system of claim 8 wherein the water supply provides pressurized feed water and the pressure of the water supply drives, directly ar indirectly, the flows through the system and network of pipes.