FIELD OF INVENTION:
[0001]. The present invention relates to an electro dialysis (ED) system for
purification of industrial RO reject water by separation of anion and cations.
[0002]. Further, the present invention also provides electro dialysis process for
separating the cations and anions without adding any extra chemical and solvents.
BACKGROUND AND PRIOR ART:
[0003]. In HMC, a large amount of water is used for coke quenching. There is a
movement toward not just preventing the waste water from causing pollution, but
also to treat the waste water and recycle it in a closed system with the objective of
conserving diverted water.
[0004]. To address this issue a technology includes electro dialysis was developed.
[0005]. Electro-dialysis is an electro membrane process in which ions are
transported through ion permeable membranes from one solution to another under
the influence of a potential gradient. The electrical charges allow the ions to be
driven through the membranes fabricated by ion exchange polymers. Since the
membranes used in electro-dialysis can selectively transport ions having positive or
negative charge and reject ions of the opposite charge, useful concentration, removal
or separation of electrolytes can be achieved by electro-dialysis.
[0006]. Electro-dialysis is a powerful separation technique with applications in the
following areas due to its advantages of being environmental friendly, high
separation performance, ease of operation and low energy consumption.
i. Recovery of salts, acids, and alkali from industrial rinse waters
ii. Brackish water desalination
iii. Nitrate removal for drinking water
iv. Food/sugar products desalting
v. Sodium chloride removal from amino acid salts
vi. Removal of ionic impurities from organic product.

[0007]. By electro-dialysis technique the anions (Cl- and SO42-) and cations (Na+,
Ca2+, K+ and Mg2+) were removed from the industrial R.O. reject water. A
maximum of 2900 ppm of chloride and 800 ppm sulphate ions were removed with
56% current efficiency and 98% removal efficiency.
Some of patent and non-patent literature are given below:
[0008].Yang Zhang et al. (Journal of Membrane Science 378 (2011) 101– 110,
Electro-dialysis on RO concentrate to improve water recovery in wastewater
reclamation) investigates the feasibility of electro-dialysis (ED) on the RO
concentrate to reduce the volume of salty water discharge and to improve the overall
water recovery to produce infiltration water for groundwater recharge. In the pilot
system, the decarbonation process was used to reduce scaling potential of the feed
or the concentrate stream of the ED. Based on various experiments in batch and in
feed-and-bleed mode, ion transport mechanisms were studied to monitor the
effluent water compositions
[0009]. International Journal of Applied Environmental Sciences ISSN 0973-
6077 Volume 12, Number 3 (2017), pp. 489-503 review about the treatment of
RO reject from the effluent of textile, pharmaceutical and leather industry to reduce
the environmental impacts on further disposal of RO concentrate. RO reject
however cannot be further purified due to the presence of high concentration of
organic pollutants and high osmotic pressure must be treated before discharging.
[00010]. US Patent 2424975 relates to the separation of alkali metal sulphates
from mixtures thereof with alkali metal carbonates, and more particularly to the
separation of potassium sulphate from a mixture of Sodium and potassium
carbonates secured by the extraction of the mineral Wyoming With an aqueous
solution of calcined. Wyomingite is a potash-containing mineral.
[00011]. R.O Reject Water Management Techniques, Available online at
www.worldnewsnaturalsciences.com to meet with the growing water
requirements, along with the waste water from municipal sewage treatment plant,
it is critical to consider the reuse of waste water from the industries wherever
possible. In the Indian context, this has already been started in some of the big

industries especially in metro cities and it must be implemented at all level possible
industries. Ultrafiltration (UF), reverse-osmosis (RO) and a membrane bioreactor
(MBR) will all be an integral part of this. From last five decades, the variation for
increase in population and decrease in available clean water is noticeable. Waste
water reuse is not only the requirement but it also provides several eco-friendly
benefits.
[00012]. Rasayan Journal of Chemistry, Vol. 10 | No. 4 |1114-1118 | October -
December | 2017 investigates ABR study was carried out in a lab scale using RO
as a feeding material. In this investigation, the anaerobic bio treatment process was
carried out to reduce the Biological Oxygen Demand (BOD) concentration. ABR
has the advantage of operating at even reduced flow rates to ensure contact between
the RO reject feed and micro-organism. As a result of anaerobic digestion, ABR
will produce a biogas as a by-product. By investigating various characteristics, it
was observed that there is a consequential percentage decrease in BOD and COD.
[00013]. INTERNATIONAL JOURNAL OF ENVIRONMENTAL
SCIENCES Volume 3, No 6, 2013 relates to the disposal or management of
desalination brine (concentrate) is expensive and faces major environmental
challenges. In spite of the scale of this economic and environmental problem, the
options for brine management have been limited. This brief review presents an
overview of the existing methods on brine treatment, minimization, and disposal
practices based on the newest and most updated technologies. In addition, the
review outlines the advantages and disadvantages of the most common treatment
and disposal methods from an environmental perspective.
[00014]. International Journal of Applied Environmental Sciences ISSN
0973-6077 Volume 12, Number 3 (2017), pp. 489-503 review about the treatment
of RO reject from the effluent of textile, pharmaceutical and leather industry to
reduce the environmental impacts on further disposal of RO concentrate.
[00015]. In RO reject processing, the maximum efficiency of alternate treatment
depends on the nature of industries and effluent. The maximum efficiency was
achieved by oxidation processes in majority of industrial effluents. Hence the future

studies are carried out in deeper to understand the process in better and utilize it in
most efficient way.
[00016]. Desalination 452 (2019) 159–195 relates to highly polluted water
resources have put critical stress on the existing conventional pre-treatment
techniques, whereby membrane pre-treatment has emerged as a promising
alternative. This paper provides an overview of the development and current trends
in conventional and non-conventional RO pre-treatment techniques whereby the
techniques are critically reviewed to inform readers of potential improvements in
such areas. This paper addresses the major drawbacks of conventional pre-treatment
methods which have necessitated the use of membrane pre-treatment techniques.
Special attention is given to microfiltration, ultrafiltration and nano-filtration
methods and their development in terms of advanced membrane materials based on
ceramics and self-cleaning membranes.
[00017]. Hence, there is always a need to develop an improved electro-dialysis
system alongwith a method to purify the RO reject water.
[00018]. The present invention meets the long felt need.
OBJECTS OF THE INVENTION
[00019]. It is therefore an object for the present invention to provide an electro
dialysis system or cell for separation of anion and cations from the industrial RO
reject water without addition of any extra chemicals and solvents.
[00020]. Another object for the present invention to provide an electro dialysis
system, where cations and anions are separated physically followed by recovery of
different value added chemicals like sodium hypochlorite.
[00021]. Yet another object for the present invention to provide an electro
dialysis method for separating anion and cations from industrial RO reject water in
a single operation or process at a room temperature and atmospheric pressure.
[00022]. Another object for the present invention to provide an electro dialysis
method for separating anion and cations, without addition for any extra chemicals
and solvents.

[00023]. Still another object for the present invention to provide an electro
dialysis method for separating anion and cations, which is eventually facilitates the
preparation of different value added products like NaClO, NaOH, KOH, Ca(OH)2
and Mg(OH)2.
[00024]. Further another object for the present invention to provide an electro
dialysis method for separating anion and cations, which is simple, rapid and
environment friendly.
SUMMARY OF INVENTION
[00025]. While the embodiments of the disclosure are subject to various
modifications and alternative forms, specific embodiment thereof have been shown
by way of the figures and will be described below. It should be understood,
however, that it is not intended to limit the disclosure to the particular forms
disclosed, but on the contrary, the disclosure is to cover all modifications,
equivalents, and alternative falling within the scope of the disclosure.
[00026]. The present invention relates to an electro-dialysis (ED) system for
purification of industrial RO reject water, the electro dialysis system comprises
three compartments; a middle compartment provided with a cation exchange
membrane (CEM) and an anion exchange membrane (AEM); an anolyte chamber;
and a catholyte chamber along with an anode and a cathode.
[00027]. Further, the present invention also provides an electrolytic method for
purification of industrial RO reject water obliterating any necessity for adding any
extra chemicals and solvents, said method comprising the steps of: i) placing RO
reject water as a feed solution in the feed chamber of a three compartment Electro-
dialysis (ED) cell; ii) taking 0.1 – 1 % or preferably 0.6% sodium hydroxide
(NaOH) (w/v) solution as anolyte and 1 – 2 % Sodium chloride (NaCl) solution as
catholyte in anolyte and catholyte chambers respectively along with the suitable
anode and cathode; iii) conducting electro-dialysis under constant current for a
duration of 7 hours.

[00028]. Various objects, features, aspects, and advantages of the inventive
subject matter will be more apparent from the following details of preferred
embodiments, along with the accompanying drawing figures.
[00029]. It is to be understood that the aspects and embodiments of the disclosure
described above may be used in any combination with each other. Several of the
aspects may be combined to form a further embodiment of the disclosure.
[00030]. The foregoing summary is illustrative only and is not intended to be in
any way limiting. In addition to the illustrative aspects, embodiments, and features
described above, further aspects, embodiments will become apparent by reference
to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS:
[00031]. The illustrated embodiments of the subject matter be best understood by
reference to the drawings. The following description is intended only by way of
example, and simply illustrates certain selected embodiments of method, systems,
that are consistent with the subject matter as claimed herein, wherein:
[00032]. Figure 1 illustrates 600ml capacity electro dialysis (ED) system having
three compartments
[00033]. The figures depict embodiments of the disclosure for purposes of
illustration only. One skilled in the art will readily understand from the following
description that alternative embodiments of the structures and methods illustrated
herein may be employed without departing from the principles of the disclosure
described herein.
DETAILED DESCRIPTION OF THE PRESENT INVENTION WITH
PREFERRED EMBODIMENTS:
[00034]. One or more drawbacks of conventional electrolytic method for
desalination of industrial RO reject water are overcome, and additional advantages
are provided through the method as claimed in the present disclosure, additional
features and advantages are realized through the technicalities of the present

disclosure. Other embodiments and aspects of the disclosure are described in detail
herein and are considered to be part of the claimed disclosure.
[00035]. It is to be noted that a person skilled in the art would be motivated from
the present disclosure to arrive at an electro dialysis system and a methodology for
purification of the RO reject water. Such method may vary based on configuration of
one or more ingredients. However, such modifications should be construed within the
scope of the disclosure. Accordingly, the drawings illustrate only those specific
details that are pertinent to understand the embodiments of the present disclosure, so
as not to obscure the disclosure with details that will be clear to those of ordinary skill
in the art having benefit of the description herein.
[00036]. As used in the description herein and throughout the claims that follow,
the meaning of “a”, “an”, and “the” includes plural reference unless the context
clearly dictates otherwise.
[00037]. The terms “comprises”, “comprising”, or any other variations thereof used
in the disclosure, are intended to cover a non-exclusive inclusion, such that a method,
electro-dialysis reject water, cation, anion that comprises a list of components does
not include only those components but may include other components not expressly
listed or inherent to such method. In other words, one or more elements in a method
proceeded by “comprises…..a” does not, without more constraints, preclude the
existence of other elements or additional elements in the method.
[00038]. Hereinafter, a description of an embodiment relates to an innovative
electro dialysis (ED) system for purification of industrial RO reject water through
physical separation of anions and cations.
[00039]. The present invention also facilitates the removal of chloride ion by
selective nano filtration membrane which provides 80% recovery of the feed water
from coke quenching and 20% reject water generated with chloride concentration of
4 times to the feed.
[00040]. The electro dialysis (ED) system or ED cell comprises three
compartments:

i) Middle compartment or feed chamber with a cation exchange membrane
(CEM) and an anion exchange membrane (AEM);
ii) Anolyte chamber with anode;
iii) Catholyte chamber with cathode;
[00041]. Figure 1 illustrates electro dialysis (ED) system of 600ml capacity having
three compartments.
[00042]. Middle Compartment or Feed Chamber: 600 ml of industrial RO reject
water was taken as a feed solution in the feed chamber and the electro-dialysis was
carried out. After the electro-dialysis, the feed solution is subjected to analyse for
anions and cations.
[00043]. Anolyte Chamber: 450ml solution of 0.6% NaOH (w/v) was taken as
anolyte and graphite is used as anode the in the anolyte chamber. After the electro-
dialysis, the anolyte solution was analyses. The formation of NaClO is found in the
range of 1-2% w/v.
[00044]. Catholyte Chamber: 450ml solution of 1-2 % NaCl (w/v) was taken as
catholyte and graphite is used as cathode in the catholyte chamber. After electro-
dialysis, the catholyte solution was filtered to remove the solid Ca(OH)2 and the
amount of NaOH/KOH was analyses to know its concentration.
[00045]. The ED cell also contain a cation exchange membrane (CEM) and one
anion exchange membrane (AEM) with anode and cathode.
[00046]. The area of cathode and anode is 80cm2 each.
[00047]. Further the dimension of all three chambers such as feed chamber,
anolyte chamber and catholyte chamber is of 11cm x 5.5 cm x 12.5cm (Length x
width x height).
[00048]. In accordance with another embodiment of the present invention, an
electrolytic method is provided for purification of RO reject water without addition
of any extra chemicals and solvents followed by recovery of different valuable
chemicals.

[00049]. Before electro dialysis, the feed water was analysed to know the
concentration of cations and anions present in the sample and after the electro
dialysis method, the RO reject water is subjected to different analysis for checking
the residual anions and cations. Graphite plates were used as anode and cathode i.e.,
cathode and anode are made up with graphite materials. 0.1 to 1.0% NaOH solution
was taken as anolyte solution and 1 to 2% NaCl solution can be used as catholyte
solution.
[00050]. In this electrolytic method, a three compartment ED cell is utilized. For
600ml RO reject water, taken in the middle compartment or feed chamber, 450ml of
0.6% NaOH and 450ml of 1 to 2 % NaCl solution were also taken as anolyte and
catholyte chambers respectively.
[00051]. The electro dialysis is conducted at current density in a range of 1 to 10
mA/cm2 under constant current electrolysis technique with a current rate of 800 to
100mA. The duration of total electro dialysis is 7 hours at a cell voltage of 6.8 to
32V.
Example 1:
[00052]. Optimized experimental condition for the 600ml capacity electro-dialysis
(ED) system is captured in Table 1. A three compartment ED cell was used with
cation exchange membrane (CEM) and anion exchange membrane (AEM) with
graphite as anode and cathode. 600 ml of feed (RO reject) was taken in the feed
chamber (middle compartment) and 450 ml of 0.6% NaOH and 450 ml of 1 to 2 %
NaCl solutions was taken as anolyte and catholyte in respective chambers. Electro-
dialysis was conducted at a range of 1 to 10 mA/cm2 current density under constant
current electrolysis technique. A total Electro-dialysis duration was 7 hours and cell
voltage observed was in between 6.8 to 32.0 V. The total current (charge) passed for
the electro-dialysis of 600 ml feed solution was 2400 mAh or 2.4 Ah.
[00053]. The total charge or current passed for electro dialysis of 600ml feed
solution is 2400 mAH or 2.4Ah in anolyte compartment. The pH maintained is 14
by addition of extra Sodium hydroxide (NaOH) solution throughout the electro-
dialysis process.

[00054]. The optimized experimental condition for 600ml capacity of electro
dialysis (ED) system was provided in the below table

[00055]. Feed, catholyte and anolyte were analyzed periodically and the cell
voltage developed was noted. Chloride, hypochlorite and calcium contents were
estimated by volumetric titration and compared with the standard samples.
[00056]. Different value added products like Sodium hypochlorite (NaClO),
Sodium hydroxide (NaOH), Potassium hydroxide (KOH), Calcium hydroxide
(Ca(OH)2) and Magnesium hydroxide (Mg(OH)2) can be procured by the electro
dialysis method of industrial RO reject water as claimed hereinafter.
[00057]. The analysis data for the electro dialysis and specification are given in
Table 2 and Table 3.


[00058]. Table 2 shows the analysis report of ions present in the solution before
and after electro-dialysis of RO reject water. The TDS of the solution was reduced
to 80 ppm from 4000 ppm and the hardness also reduced to 5 ppm from 748 ppm.

[00059]. The chloride ion concentration was reduced to 70 ppm from the initial
concentration of 3000 ppm. Sulphate ion concentration was 850 ppm in the feed
solution and it is reduced to 50 ppm. In this manner, the concentration of Na+, Ca2+,
K+ and Mg2+ ions were reduced to 18, 10, 1, 2 ppm from its initial feed concentration
of 2300, 748, 260 and 98 ppm. Table 2 reveals that after the electro-dialysis of RO
reject water, the concentration of cations reduced to standard limit of water (IS-
10500: 2012, BIS-105000: 2009) and the concentration of cations eg Na+, Ca2+, K+
and Mg2+ were reduced to permissible standard limit of water (IS-10500: 2012,
BIS-105000: 2009).
[00060]. Further, in accordance with another embodiment of the present
disclosure, removal of chloride (Cl) ion from RO reject water is also an important
feature.
[00061]. Thus, experiments were carried out to remove Cl- ions from RO reject
water under constant current electrolysis according to the standard limit.
Example 2:
[00062]. During the experiment, the current was passed stepwise from higher
amount to lower with stipulated time, i.e. 700 mA current was passed for first one
hour then 500 mA for second hour and likewise step-down current was passed until
the chloride ions reduced to 70 ppm.
[00063]. The experimental conditions for the above-mentioned experiments are
given below:
Anode : Graphite
Anolyte : NaOH (0.6%w/v)
Total charge passed : 2400 mAh
Feed Cl- Content : 3000 ppm
Cathode : Graphite
Catholyte : NaCl (1.0%w/v)
Temperature : 33oC

Feed : 600ml
Duration : 7 hours
[00064]. Table 4 provides the experimental results for removal of chloride ion
efficacy or more particularly reveals the effect of current passed for removal of Cl-
ions from RO reject water by the electro-dialysis method.

Example 3:
[00065]. Another experiment was performed for removal of Cl-ion from RO reject
water under constant current rate technique i.e., a constant current 400mA per hour
was passed for the entire electro-dialysis method.
[00066]. To minimize the electro-dialysis duration, the effect of current density
studies was carried out in the range of 10 to 5 mA/cm2. From the above studies, it
reveals that at high current densities like 10 mA/cm2 or 7 mA/cm2 the removal of
chloride ion was low (2755 & 2860 ppm) or removal efficiency was less as compared
to the current density of 5 mA/cm2. At current density of 5 mA/cm2 the amount of
chloride ion removal was 2930 ppm with 98% removal efficiency. Based on the
requirement of chloride ions content in the feed solution after electro-dialysis, the

higher current density may be chosen and accordingly the energy consumption may
be reduced.
[00067]. The experimental conditions for the above-mentioned experiments are
given below:
Anode : Graphite
Anolyte : NaOH(0.6%)
Temperature : 33ºC
Total charge passed : 2400 mAh
Cathode : Graphite
Catholyte : NaCl (1.0%)
Feed : 600 ml
Feed Cl- Content : 3000 ppm
[00068]. Table 5 shows the effect of constant current densities at different level on
removal of Cl- ions from the RO reject water. These studies mainly reveal the
reduction of electro dialysis time as well as energy consumption.

[00069]. From table 4 and 5, it can be concluded that after electro-dialysis, 2930
ppm ions were removed from the RO reject water with 98% removal efficiency and
56% current efficiency. 95% water recovery efficiency was achieved by this electro-

dialysis technique. The energy consumption or energy requirement for the treatment
of 600 ml of RO reject water is 60 watts or 0.006kWh [100 watts/0.010 kWh per
litre].
[00070]. Further, in accordance with another embodiment of the present invention,
there is provided a chemical process for preparation of value added product such as
sodium hypochlorite (NaClO).
[00071]. NaClO formation is observed in the anolyte solution with 0.39 to 1.69 gpl
chlorine content. Some amount of sulphate ions also available in the anolyte
solution. The formed NaClO compound is not stable and the concentration is
decreased with respect to the time. Hence studies have been carried out to maintain
the NaClO for a particular time period
Reaction mechanism in the anolyte chamber:

[00072]. After completion of electro-dialysis, the anolyte solution was analyzed.
NaClO formation is observed in the anolyte solution with available chlorine content
in the range of 0.39 to 1.69 gpl.
[00073]. Apart from that, some amount of sulphate ions are also available in the
anolyte solution. The formed NaClO compound is not stable and the concentration
decreased with time.
[00074]. Different experimental condition for NaOCl formulation is given as
below:
Anode : Pt/DSA/Graphite
Anolyte : NaOH(0.6%)
Temperature : 25-33ºC
Duration : 3 hours
Cathode : Graphite

Catholyte : NaCl (1.0%)
Feed : 600 ml
Feed Cl- Content : 3000 ppm
[00075]. Further, the details of current density, rate, amount of Sodium Chlorite
(NaClO2), and Cl- are also provided in Table 6.

[00076]. Table 6 reveals the effect of various electrodes used for the in-situ
generation of NaClO at anolyte chamber during electro-dialysis of RO reject water.
Experiments were carried out by employing different anode materials like platinum,
Dimensionally Stable Anode for chloride evolution [DSA-Cl2] and graphite.
Constant current density of 20 mA/cm2 was applied to all the electrodes during
electro-dialysis. To maximize the formation of NaClO above conventional
electrodes were used. Table 6 reveals that DSA-Cl2 type electrode assured higher
amount of NaClO formation than the other electrodes. A maximum of 1.6992 gpl of
free chlorine was identified in NaClO by employing this DSA-Cl2 type electrode.
This type of electrode is stable in the NaClO solution even at higher concentration
and also commercially available.
[00077]. Further, the efficacy of the electrolysis method are provided below in
terms of different experimental value:
i) The TDS of the solution was reduced to 80 ppm from 4000 ppm
ii) The hardness also reduced to 5 ppm from 748 ppm
iii) The chloride ion concentration was reduced to 70 ppm from the initial
concentration of 3000 ppm

iv) Sulphate ion concentration was 850 ppm in the feed solution and it is
reduced to 50 ppm
[00078]. In this manner, the concentration of Na+, Ca2+, K+ and Mg2+ ions were
reduced to 18, 10, 1, 2 ppm from its initial feed concentration of 2300, 748, 260 and
98 ppm respectively.
[00079]. The process as claimed to separate/remove anions & cations from the
industrial RO reject water was with 98% removal efficiency and 56% current
efficiency.
[00080]. The above mentioned electro-dialysis technique claimed 95% water
recovery efficiency.
[00081]. Further, table 7 also provides the data of anions and cations presented in
the RO reject water, which have been removed efficiently.

[00082]. Each of the appended claims defines a separate invention, which for
infringement purposes is recognized as including equivalents to the various elements
or limitations specified in the claims. Depending on the context, all references below

to the “invention” may in some cases refer to certain specific embodiments only. In
other cases, it will be recognized that references to the “invention” will refer to
subject matter recited in one or more, but not necessarily all, of the claims.
[00083]. Groupings of alternative elements or embodiments of the invention
disclosed herein are not to be construed as limitations. Each group member can be
referred to and claimed individually or in any combination with other members of
the group or other elements found herein. One or more members of a group can be
included in, or deleted from, a group for reasons of convenience and/or patentability.
When any such inclusion or deletion occurs, the specification is herein deemed to
contain the group as modified thus fulfilling the written description of all groups
used in the appended claims.
Equivalents:
[00084]. With respect to the use of substantially any plural and/or singular terms
herein, those having skill in the art can translate from the plural to the singular and/or
from the singular to the plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth herein for sake of
clarity.
[00085]. It will be understood by those within the art that, in general, terms used
herein, and especially in the appended claims (e.g., bodies of the appended claims)
are generally intended as “open” terms (e.g., the term “including” should be
interpreted as “including but not limited to”, the term “having” should be interpreted
as “having at least”, the term “includes” should be interpreted as “includes but is not
limited to”, etc.). It will be further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an intent will be explicitly
recited in the claim, and in the absence of such recitation no such intent is present.
For example, as an aid to understanding, the following appended claims may contain
usage of the introductory phrases “at least one” and “one or more” to introduce claim
recitations. However, the use of such phrases should not be construed to imply that
the introduction of a claim recitation by the indefinite articles “a” or “an” limits any
particular claim containing such introduced claim recitation to inventions containing

only one such recitation, even when the same claim includes the introductory phrases
“one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a”
and/or “an” should typically be interpreted to mean “at least one” or “one or more”);
the same holds true for the use of definite articles used to introduce claim recitations.
In addition, eve it a specific number of an introduced claim recitation is explicitly
recited, those skilled in the art will recognize that such recitation should typically be
interpreted to mean at least the recited number (e.g., the bare recitation of “two
recitations”, without other modifiers, typically means at least two recitations, or two
or more recitations).
[00086]. The above description does not provide specific details of the method of
the various parameters. Those of skill in the art are familiar with such details, and
unless departures from those techniques are set out, techniques, known, related art
or later developed designs and materials should be employed. Those in the art are
capable of choosing suitable manufacturing and design details.
[00087]. The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the present disclosure. It will
be appreciated that several of the above-disclosed and other features and functions,
or alternatives thereof, may be combined into other methods or applications. Various
presently unforeseen or unanticipated alternatives, modifications, variations, or
improvements therein may subsequently be made by those skilled in the art without
departing from the scope of the present disclosure as encompassed by the following
claims.
[00088]. The claims, as originally presented and as they may be amended,
encompass variations, alternatives, modifications, improvements, equivalents, and
substantial equivalents of the embodiments and teachings disclosed herein, including
those that are presently unforeseen or unappreciated, and that, for example, may arise
from applicants/patentees and others.
[00089]. While various aspects and embodiments have been disclosed herein,
other aspects and embodiments will be apparent to those skilled in the art. The
various aspects and embodiments disclosed herein are for purposes of illustration

and are not intended to be limiting, with the true scope and spirit being indicated by
the following claims.

WE CLAIM:
1. An electro-dialysis (ED) system for purification of industrial RO reject water,
said electro dialysis system comprises three compartments:
a middle compartment provided with a cation exchange membrane (CEM)
and an anion exchange membrane (AEM);
an anolyte chamber; and
a catholyte chamber along with an anode and a cathode.
2. The electro-dialysis system as claimed in claim 1, wherein 0.1 – 1 % sodium
hydroxide (NaOH), preferably 0.6% NaOH acts as anolyte in the anolyte chamber.
3. The electro-dialysis system as claimed in claim 1, wherein the catholyte chamber
is filled with 1 – 2 % Sodium Chloride (NaCl) solution as catholyte in the respective
chambers along with the suitable anode and cathode.
4. The electro-dialysis system as claimed in claim 1, wherein the cathode and the
anode are made of graphite material.
5. The electro-dialysis system as claimed in claim 1, wherein a current density of 1
to 10 mA/ cm2 for a duration of 7 hours is mandated for the electro-dialysis.
6. The electro-dialysis system as claimed in claim 1, wherein a voltage between 6.8
to 32.0 V at room temperature is mandated for the electro-dialysis.
7. The electro-dialysis system as claimed in claim 1, wherein the area of said
cathode and anode is 80 cm2.
8. An electrolytic method for the purification of industrial RO reject water
obliterating any necessity for adding any extra chemicals and solvents, said method
comprising the steps of:
i) placing RO reject water as a feed solution in the feed chamber of a three
compartment Electro-dialysis (ED) cell;

ii) taking 0.1 – 1 % or preferably 0.6% sodium hydroxide (NaOH) (w/v)
solution as anolyte and 1 – 2 % or preferably 1 – 2 % Sodium Chloride (NaCl)
solution as catholyte in anolyte and catholyte chambers respectively along with the
suitable anode and cathode; and
iii) conducting electro-dialysis under constant current for a duration of 7
hours.
9. The electrolytic method as claimed in claim 8, wherein the cathode and anode
are made up of graphite material.
10. The electrolytic method as claimed in claim 8, wherein the pH is maintained at
14 in the anolyte chamber through additional addition of NaOH solution.
11. The electrolytic method as claimed in claim 8, wherein the electro-dialysis is
conducted at a current density of 1 to 10 mA/ cm2 at a current rate of 800-100 mA.
12. The electrolytic method as claimed in claim 8, wherein the cell voltage is
maintained in a range of 6.8 to 32 V during the process.
13. The electrolytic method as claimed in claim 8, wherein 600ml feed solution was
taken in the feed chamber.
14. The electrolytic method as claimed in claim 8, wherein 2930 ppm ions were
removed from the RO reject water with 98% removal efficiency, 56% current
efficiency and 95% water recovery efficiency.