FQRM-2
THE PATENTS ACT. 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003 COMPLETE SPECIFICATION
(See Section 10; Rule 13)
1. TITLE OF THE INVENTION;
"Indion Maximum Efficiency Reverse Osmosis Process (I-MRP)"
2. APPLICANT:
(a) NAME: ION EXCHAGE (INDIA) LIMITED.
(b) NATIONALITY: AN INDIAN COMPANY INCORPORATE UNDER
THE COMPANIES ACT, 1956.
(c) ADDRESS: TIECICON HOUSE,
DR. E. MOSES ROAD, MAHALAXM1, MUMBAI-400 011, MAHARASHTRA, INDIA.
The following specification describes the nature of the invention and the manner in which it is to be performed:-

5. PREAMBLE TO THE DESCRIPTION
Field of Invention
The present invention relates to a method to treat water & wastewater through membrane based process and to apparatus for carrying out the method. The embodiments of the invention relates to the method for pretreatment and for the operation of reverse osmosis system through which it is possible to achieve the maximum possible recovery and producing a concentrated stream which can be easily treated through evaporators without fouling the tubes.
Background of the Invention & the Related Art
In recent years, with the development of industries, increase in population and improved living standard demand of water has remarkably increased. The communities in many Indian cities have to purchase the drinking water at a high cost of Rs. 50 - 150 per m3 . Since water has become a scarce commodity, it is necessary for all the industries to positively implement all kinds of programs and measures for effective utilization of water resources. As per the new government policy, new manufacturing units can only start production, if they go for zero liquid discharge. Even the existing units had to cut down their discharge and for expansion they had to survive with the existing water supply. The final unit to achieve zero liquid discharge is evaporators which involve huge capital cost, operating cost, and tedious operations.
In this scenario a continuing demand exists for simple, efficient, and inexpensive process which can reliably provide water of desired purity and minimum effluent

during the course of treatment in order to minimize the size of evaporators. Also the effluent needs to be with minimum scaling components.
The conventional membrane based processes are limited in terms of the recovery and the flux rates based on the scaling and the fouling tendencies of the feed water. The colloidal fouling is due to the presence of metal oxides, soaps, detergents, proteins, organic matter, silicates and clay; biofouling is due to the presence of micro organism; and scaling is due to the presence of the sparingly soluble ions and their salts such as CaC03, MgC03, CaS04, BaS04, SrS04} CaF2, Si02, etc. It is the need of the time to reduce the scaling and fouling tendencies of the feed water to the point where, the recovery limits would be dictated by osmotic pressure and economic terms.
The current designs are based on the reduction of hardness and silica to a low level in solids contact clarifier, reducing the pH to almost neutral/acidic, filtration through media filter, colloid removal by ultra filtration membranes and salt reduction by reverse osmosis membranes. It is possible to achieve the total hardness less than 50 mg/L and silica less than 20 mg/L by continuous monitoring of the parameters and the strict chemical treatment, many a times we are not able to achieve the desired results to human error. This limits the recovery through RO to a maximum of 75%. Also, the treatment units involved, makes the treatment a costly affair.
Various attempts have been made by researchers to get rid of scaling and fouling and achieve the high recovery through RO. One such attempt is made by Tao et. al., for Reducing Aqueous Boron Concentrations with Reverse Osmosis Membranes Operating at High pH as shown in US Patent No. 5250185 dated Oct 05, 1993. The process used for reducing boron and hydrocarbon concentration is Zeolite softeners followed by the weak acid softeners and the reverse osmosis

membranes. The pH of RO feed was increased to 10.5 for ionizing boron and solubilizing hydrocarbons. The application of the process is w.r.t. treatment of produced water so that it can be safely discharged. The patent does not talk about the recycling or the recovery of water.
One other method as shown in World Intellectual Property Organization publication No. WO 98/06483 issued February 19, 1998 to Mukhopadhyay for Method and Apparatus for High Efficiency Reverse Osmosis. Inventor talks about the treatment methods to produce very high purity product water. The equipments used are Weak acid cation exchanger column for removal of the hardness followed by the degasser for the reduction/removal of non hydroxide alkalinity and RO membranes operating at high pH for removal of species which are sparingly ionized at neutral or near neutral pH in aqueous solution. Although, the method provides hardness and alkalinity removal, protects the membranes from scaling and fouling, and leads to increase the recovery and flux, the overall efficiency is limited to less than 85% due to effluent streams from WAC regeneration and reject from RO.
Also a patent filed by Jagannathan et. al. (Aquatech International Corporation), Reverse Osmosis Enhanced Recovery Hybrid Process with World Intellectual Property Organization (Publication No. WO 2010/017303 A2 dated Feb 11, 2010) talks about high recovery integrated recycling process for the water and the wastewater rich in hardness, silica, and other contaminants. Here, inventor talks about the recovery of 60 - 95 % based on contaminants present in the feed water. Continuous operation of RO unit is taken care off by removal of scaling ions in clarifier and low recovery through membranes. But our experience says that the colloidal fouling of membranes can't be ruled out and use of the UF membranes is inevitable. Moreover, the recycling of RO reject is almost 125% of feed flow

leading to increase in size of the pre treatment equipments as well as operating cost.
In contrast to prior processes for the water and the wastewater treatment, we propose a process for the treatment of water and wastewater which will provide maximum recovery up to 99% by eliminating the scaling and fouling of membranes during pretreatment.
4. DESCRIPTION OF THE INVENTION
SMMARY OF THE INVENTION
The invention described herein is a process of treating the water and the wastewater, such as cooling tower blow down, rich in hardness, silica, metals etc and to recover water to the maximum extent. The multi step process comprises of softening clarifier with lime, soda ash and polyelectrolyte dosing for removal of the hardness and the silica, filtration for removal of suspended solids, weak acid cation exchanger in hydrogen form for removal of hardness slip from clarifier, alkali dosing for raising the pH to a level suitable for safe operation of reverse osmosis membranes, micron cartridge filter for protection of membranes, and reverse osmosis / nano filtration membranes for reduction of ions from the liquid. Reject of one stage is treated through WAC column to reduce calcium carbonate before passing through next stage. The filter backwash as well as WAC regeneration effluent is recycled back to the softening clarifier for removal of suspended solids and hardness respectively. The novel process leads to almost 99% recovery if osmotic pressure is not a limit. Moreover, reject from the final stage is rich in non scaling salts resulting in ease of evaporator operation.

DETAILED DESCRIPTION OF THE INVENTION
The invention under consideration is a new method for treatment of the water and the wastewater rich in suspended solids, hardness, metals, silica, etc. The process will lead to achieve maximum overall recovery with minimal operational cost.
The first step is the treatment of the feed water through clarifier (preferably solids contact clarifier) for the reduction of suspended solids, hardness, silica, and metals. The reduction of these species will be achieved by dosing soda ash, calcium, magnesium, and aluminum salts in reaction tank (1). The silica removal desired in the solids contact clarifier (2) is based on the operating reverse osmosis pH and the recovery. The coagulants and polyelectrolyte will be dosed for better solid liquid separation. The underflow from the clarifier is treated through the sludge handling equipments (3) and the filtrate is recycled back to the reaction tank/clarifier. The contaminants (hardness and metals) are converted to solids as compared to other high pH process which generate another liquid stream.
The second step is the removal of suspended solids for the softened and the clarified water. This is achieved by using two stage media filtration (4). Other type of filters like self cleaning filters (e.g. Amiad) can also be used. Filter backwash is recycled back to the reaction tank/clarifier.
The third step involves the removal of slip out hardness and the metal ions from clarifier by utilizing weak acid cation resin (e.g. Indion 236, IRC 86, MAC -3, etc.) in hydrogen form (5). The resin is operated on the hardness breakthrough. Since, I-MRP process reduces hardness to almost 50 mg/L in solids contact clarifier, requirement of resin quantity as well as the regeneration chemical comes down. Also, the regeneration effluent which is rich is non alkaline hardness is recycled back to the reaction tank. Since, bicarbonate/carbonate concentration in

WAC treated water is only 35 mg/L as CaC03 associated with sodium, I-MRP process does not require degasser for removal of carbon dioxide as is desired in HERO process and hence dosage of acid for reducing the pH in order to convert all the bicarbonate to C02 is eliminated.
Fourth step involves addition of the caustic (6) to WAC treated water to increase the pH to level which will lead to the maximum pH in the RO reject suitable for the membrane element. This leads to conversion of carbonic acid to sodium carbonate/bicarbonate. Presence of sodium carbonate/bicarbonate produces a buffering effect and hence the reject pH does not increase exponentially leading to smooth and stable operation.
The final step involves the demineralization of high pH WAC treated water through reverse osmosis membranes (7, 8, & 10) to produce the desired quality water based on requirement. The reject from the second stage (8) is treated through WAC column (9) before treating through the 3rd stage (10) for ensuring the feed to the third stage is the devoid of any hardness contributing ions. WAC regeneration effluent is recycled back to solids contact clarifier. The reject from the 3rd stage is treated through the evaporator (11) for further treatment. Condensate from evaporator will be low in TDS and is blended with RO permeate.
EXAMPLE
In order to ensure the efficacy of the proposed process a lab scale piloting was done with effluent collected from a power plant. The effluent streams were blended in same proportion as generated in order to achieve a composite sample. The characteristics of effluent streams are as shown in table 1.

The composite effluent was treated for the hardness removal by dosing 540 mg/L of lime (80% w/w purity), 1080 mg/L soda ash (90% w/w purity), 15 mg/L ferric chloride, and 1 mg/L Indfloc 443 polyelectrolyte. The total hardness and the silica content were reduced to 60 mg/L and 20 mg/L respectively whereas increase in sodium content was observed. Reduction in silica content was due to adsorption on magnesium hydroxide formed in the course of reduction.
The clarified water after the chemical precipitation was filtered through the two stage media filters for removal of the suspended solids. The filtered effluent was passed through Indion 236 (WAC) column in H form for reduction of hardness to almost nil. The quality of the effluent is shown in table 2.
The hardness free water from WAC column was fed to Brackish Water RO (BWRO) membranes (TM 710) after increasing the pH to 10. It was possible to achieve the design recovery of 80%. The quality of the reject as well as permeate of BWRO is shown in table 2.
The reject from BWRO was fed to Sea Water RO (SWRO) membranes (TM 810C) to achieve 75% recovery resulting in overall recovery of 95%. Further the recovery was not attempted keeping in view of the high pressure requirement.
The pilot plant was run continuously for a period of 3 months and the results were consistent throughout.

Table 1: Characteristics of effluent streams from power plant and composite effluent used in the trial experiment.

PARAMETERS UNIT STREAM
1 STREAM
2 STREAM
3 STREAM
4 STREAM
5 STREAM 6
Flow m3 8 5 1 23 1 38
pH — 8.0-8.5 8.0-8.5 7.0-8.0 7.8-8.0 9.0-9.5 8.0-9.0
Conductivity jiS/cm 450 26000 7500 3700 90 5920
Total suspended solids mg/L 200 50 50 40 50 75
Total dissolved solids mg/L 273 15800 4500 2200 50 3550
Ca as CaC03 mg/L 70 3000 700 280 ND 590
Mg as CaC03 mg/L 50 2000 470 200 ND 405
Na as CaCCG mg/L 66 8940 2600 1033 30 1865
Fe as CaC03 mg/L ND ND ND 1 10 I
Zn as CaC03 mg/L ND ND ND I ND —
HC03 as CaC03 mg/L 131 130 50 100 ND 80
CI as CaC03 mg/L 45 13800 3620 360 ND 2136
S04 as CaC03 mg/L 10 10 100 1050 ND 640
P04 as CaC03 mg/L ND ND ND 5 40 5
Si02 as CaC03 mg/L 15 15 150 120 0.5 85
Oil & grease mg/L ND ND ND ND ND ND
Stream 1 - Filter backwash effluent
Stream 2 - Softener effluent
Stream 3 - DM plant effluent
Stream 4 - CT blow down effluent
Stream 5 - Boiler blow down
Stream 6 - Combined stream
ND - Not detectable

Table 2: Pilot plant results
PARAMETERS UNIT Clarifier Outlet Indion
236 Outlet BWRO SWRO |

Feed Permeate Reject Permeate Reject
pH — 10-11 5.0-5.5 9.8-10.2 9.0-10.0 10.0-10.5 9.0-10.0 10.0-10.5
Total suspended solids mg/L 25 ND ND ND ND ND ND
Total dissolved solids mg/L 4055 3430 3501 191 16744 283 66630
Total hardness as CaC03 mg/L 60 ND ND ND 1 ND 4
Na as CaC03 mg/L 2776 2776 2830 160 13563 235 53853
HC03 as CaC03 mg/L ND 3 19 1.3 72 1 286
C03 as CaC03 mg/L 40 ND 37 0.9 224 3.5 1378
OH as CaC03 mg/L 20 ND ND ND ND ND ND
CI as CaC03 mg/L 2136 2136 2136 140 10125 211 39867
S04 as CaC03 mg/L 640 640 640 17 3126 19 11964
Si02 as Si02 mg/L 20 20 20 1 97 2 394

5. We claim:
1. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity.
2. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, using the solids contact clarifier for softening application.
3. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1 & 2, using a single stage media filter, multistage media filter, micron screen filter, and micro filtration membrane for removal of suspended solids.
4. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1,2 & 3, having the filter backwash being recycled back to solids contact clarifier in order to maximize recovery.
5. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3 & 4, using WAC (weak acid cation) resin for removal of scale forming compounds.

6. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3, 4 & 5, having the WAC regeneration effluent being recycled back to solids contact clarifier to get rid of hardness and minimizing the liquid effluent from the system.
7. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3, 4, 5 & 6, using the alkali dosing for the WAC treated water helping to run the RO unit efficiently.
8. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3, 4, 5, 6 & 7, the efficiency of the process is 90-99% (limiting condition is osmotic pressure).
9. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3, 4, 5, 6, 7 & 8, using the evaporators to treat RO reject in order to achieve zero discharge.
10. Indion maximum efficiency reverse osmosis process (I-MRP) for recovery of water and wastewater containing hardness, silica, and alkalinity as claimed in claim 1, 2, 3, 4, 5, 6, 7, 8 & 9, having the recycling of

evaporator condensate and being applicable to all types of membranes used in the treatment of water and wastewater, and also being able to guarantee Zero Discharge due to feasibility of using evaporators due to low volume of waste generated.