WATER PURIFICATION

AND

REVERSE OSMOSIS PROCESS

Prepared BY

MD.SHAIFUDDIN

Chemist

Transcom Beverages Limited

Chittagong Plant

What is water?

Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. Water has no color, appearance and taste.

3D STRUCTURE OF WATER

Why need water?

Water is very important for life. We need water to quench our thirst, to wash our hands, to cook, to water plants and many other things. What other important uses of water do we have? Without water, the plants would die and people and animals would get thirsty.

Source of water

Source water is untreated water from streams, rivers, lakes or underground aquifers that is used to provide public drinking water, as well to supply private wells used for human consumption. Some water treatment is usually necessary, so public utilities treat most of the drinking water before it enters the home. However, the cost of this treatment, as well as the risks to public health, can be reduced by protecting source water from contamination.

Businesses and individuals can also take actions to protect drinking water sources. Businesses can institute management practices to reduce their use of harmful contaminants or ensure their wastes do not discharge into ground or surface water.

Why need water treatment?

Some of ingredients in sources water contain at high concentration, those ingredients are risk for public health and not suitable for manufacturing of beverages. So before use ground water must be assure that is risk free for public health.

For assuring drinking water free from risky and before provider to consumer must be need treatment of sources water.

What is RO?

Reverse osmosis (RO) is a water purification process and dissolved inorganic solids (such as salts) are removed from a solution (such as water) in which water is forced through a semi-permeable membrane that removes 90-99% of tap water impurities. The result is water that is free of minerals and other contaminants.Why RO?

Now in a present world RO is only water treatedment system which reduces TDS from water. Hard of RO system is RO membrane because not only TDS of feed water reduces by Ro membrane but also all undesirable ingredients reduce from water. Better RO membrane better RO system.

Everything have limitation as like as Ro membrane limitation i that it very sensitive with some metal, cation, anion and microbial such as Chlorine, iron, Mn, Silicate, sulfate; Yeast, mold, TBC etc.

So, before entry feed water into RO membrane need to remove this metal, ion and microbial by several steps.

Why we use RO System?

TBL according to PepsiCo International always recommended to consumers for giving better quality and achieve 100% satisfaction. Now in a present Bangladesh TBL is highly promoted PepsiCo International franchisees Beverages Production Company. In beverages sector most uses raw materials is water, so without pure water is not possible to satisfy consumers. Those causes TBL use RO System.

Shortly represent the raw water treatment by RO system given below-

2%Citric Acid

ACF 32M3/H

2% AntiScaling

RO WATER TREATMENT FLOW CHART

Bore Well 100M3

R.W. Buffer Tank For RO Plant (4Nos)

20M3

R.W. Tank 200M3

4-6ppm CL2

Sand Filter 32M3/H

Polisher

-02

24M3

UV

24M3

RO Membrane

RO Reject water

100

M.F.

Storage Tank

15M3

Polisher

-01

ETP Environment

100 M.F.

1) PET LINE & GRB

2) SYRUP ROOM &

3) CIP

2% Caustic

Bore Well

With help of submersible pump surface water with drawn and storage for purification before drinking and other purpose.

Because of in nature, it is never found in pure form, rather it always contains "contaminants and by water analysis measures substances dissolved in water. These contaminants result in water characteristics such as hardness, electrical conductivity, corrosiveness, etc. Some of the substances in water pose a health risk when present in certain quantities.

TBL submersible pump capability 100M3/H

Care of Bore Well:

Daily sanitize with 200ppm chlorine and electric and mechanical care.

Raw water Storage Tank

For purification after withdrawn by bore well water need to storage and their start primary purification.

Ca (OCl) Cl + H2O = Ca(OH)2 + Cl2

Cl2 + H2O = HCl + HOCl

In storage tank two types purification is happen

1) Water Soluble Fe2+ converts to insoluble Fe3+ by oxidizing with free chlorine treatment (chlorine, ozone, Chlorine dioxide and compressed air.)

2) Primary disinfection with free chlorine treatment. Free Chlorine is primary anti-microbial agent.

TBL Raw water tank storage capacity 200m3

Care of Raw Water Tank: Every 3monthly cleaning and sanitizing.

:

Strainers

A coarse strainer including a removable basket screen with 50 to100 mesh is positioned at the intake point of surface water to remove larger particulate matter and to protect downstream equipment (e.g. pumps) from fouling which might lead to damage.

Basket Strainer screen

Sand filter

The sand filter is built on mechanical filtration principle. It uses qualified quartz sand as filtration medium to effectively remove suspended solid (Fe3+), colloid, and so on.

Note: In back wash time water flow increase gradually, otherwise possibility to damage the uniformity of sand layer and go out the sand with backwash water).Structure of Green sand:Greensand is a processed material consisting of nodular grains of the zeolite mineral glauconite. The material is coated with manganese oxide. The greensand will remove iron better, as manganese zeolite supplements the natural aeration of the water, helping to precipitate the iron.

Sand Filter work Flow: 1st oxidation by removal of Fe aeration and oxidizing agents (O2, Cl2, O3, KMnO4), and oxidized iron will then precipitate on a sand filter.

Fe+2   oxidation → Fe+3   precipitation →  Fe(OH)3/Fe2O3Changing Frequency: after 3years/ depends on performance of filter.

Check Regularly: 1) Activeness of filter i.e; removing capacity of iron.

1) Inlet and outlet pressure gauge difference i.e; filtration ability of sand filter it measuring by check flow rate.

Care of MSF:

When Sand layer is saturated, it is possible to conduct back washing to regenerate absorptive capacity of Sand layer; backwash will be done by water and by air more on iron removal capacities. If output water cannot satisfy rated requirements, change the medium. Use steam/ Chlorination to sterilize Sand layer monthly.Regeneration of sand filter:Regeneration of Manganese sand filter done with KMnO4.

Activated Carbon Filter

Active carbon filters to remove organism particle and chloride residue.HOCl + C* = HCl + C*OHypochlorous acid + carbon surface = Hydrochloric acid + carbon surface oxide

A gram of activated carbon can have a surface area in excess of 500M2, with 1500M3 being readily achievable.

Care of ACF:

When bed layer is saturated, it is possible to conduct back washing to regenerate absorptive capacity of active carbon. If output water cannot satisfy rated requirements, change the medium. Use steam to sterilize active carbon weekly.

Note: In back wash time water flow increase gradually, otherwise possibility to damage the uniformity of sand layer and go out the sand with back wash water).Changing Frequency: Every year/ depends on performance of filter.

Check Regularly: 1) Activeness of filter i.e; removing capacity of Chloride residue.

2) Inlet and outlet pressure gauge difference i.e; filtration ability of carbon filter it measuring by check flow rate.

Chemicals Dosing

Operation of the RO system perform improving with following chemicals-

1) Acids :Acids (HCl,H2SO4) are injected into the RO feed water to lowered the pH.reducing the feed water pH is to reduce the potential of calcium carbonate scaling.

3) Caustic: Caustics (NaOH) injected to increase the RO feed pH. Caution is required in raising the feed water pH as it can decrease the solubility of iron, manganese, and calcium carbonate.

4) Antiscalants:

Antiscalants are a family of chemicals designed to inhibit the formation and precipitation of crystallized mineral salts that form scale. Scaling of an RO membrane may occur when sparingly soluble salts are concentrated in the RO element beyond their solubility limit. Sparingly soluble salts are listed below in the order of decreasing scaling problem:

CaCO3 Calcium carbonate > CaSO4 Calcium sulfate > Silica (SiO2) > SrCO3 Strontium Carbonate > BaSO4 Barium sulfate > SrSO4 Strontium sulfate > CaF2 Calcium fluoride > CaSiO3 Calcium silicates > MgSiO3 Magnesium silicates > Ca3(PO4)2 Calcium Phosphate > Fe(OH)2 Iron Hydroxide

Scale inhibitors (anti-scalants) are precipitation process of sparingly soluble salts to suspended absorbed salt crystals surfaces. In this situation the crystals size grow to the concentration sufficient to suspend.

MICRON POLISHER

The 5µ micro cartridge filter is set up in RO system to stop micro particles entering RO membrane. Microfiltration (commonly abbreviated to MF) is a type of physical filtration process where a contaminated fluid is passed through a special pore-sized membrane to separate microorganisms and suspended particles from process liquid. This filter is made by PP (polypropylene filter medium) series material. The polypropylene Cartridges filter is to trap coarser particles toward the outside of the wall and the finer particles toward the inner wall. Graded-density filters have a higher dirt-holding capacity and longer effective filter life than depth filters with single-density construction.

Note: per 10 Inch of every cartridge filter able to filtrate 5 gallon per minute water. We use 14 number cartridges filters, therefore total filtrate ability of cartage filter is

5gpm × 4 ×14= 280gpm=1.06M3/m=63.6M3/H

Cartridges filter holding must be in stainless steel body.

Care of MP:

Cleaning/washing Frequency: Monthly (S.S. body cleaning with RO water / 80˚C hot water and hand brash). Changing Frequency: Monthly/ pressure difference between .07MPa=0.7 Bar=10.15Psi /micro problem)

UV LightUV is the secondary disinflationary, this unit confirm enter or no microbial into RO membrane.No change and cleaning of the UV LIGHT shelf life of RO membrane decrease. Because of RO membrane very sensitive with microbial.Check Regularly: 1) Activeness of UV Light check by calibration of radiation frequency and check the microbial after UV.

Note: Above 98% Micro Organisms killed.

RO Membrane

RO system uses RO membrane to remove ions, suspended solid, and impurity in water. Under a certain pressure, membrane can separate incoming water into two parts: one is purified water, and the other is concentrated water with salt, solid residue.

Note: Performances of RO membrane depend on the temperature, pressure and TDS of feed water.

Active parts: Outer layer – Poly Amide, Middle layer- Polysulfone Layer Inner layer- Poly Ester Base (Two materials make up the bulk of commercial RO membranes, cellulose acetate and an aromatic polyamide).

Care of RO Membrane:

Mind fresh everything thing is fresh as like as RO system membrane fresh water is fresh and quality is good. So need to always RO membrane clean and fresh. Freshness of RO membrane maintain by following work done

1) Primary disinfection with chlorination and Fe2+ to Fe3+.2) Iron(Fe3+) remove in Mn sand filter3) Chlorine remove in ACF4) Chemicals dosing as per feed water quality.5) Higher particle removing by MP6) Secondary disinfection done by UV light.

Sanitation Frequency: Monthly (At High and Low pH)RO Membrane Performance assured by:

1) Salt rejection % 2) Yield %3) Pressure difference

Water quality parameter after RO Membrane

Water Quality Parameter

SL. NO. Ingredients Name STANDARD LIMIT AS PER BDS-1240:2001

STANDARD LIMIT AS PER PI

In House lab test result

3rd party lab test result

01 Colour, Haxen Units, Max

5 5

02 Odour , Unobjectionable None None03 Taste Agreeable None None04 Turbidity NTU, Max 5 1

05 PH Value 6.4-7.4 6-8 5.8-6.1acidity ------ None None

alkalinity 50 ----- 1-306 Total Hardness, ppm 300.00 200 Zero07 Iron,ppm 0.30 0.1 Nil08 Arsenic, ppm 0.01 .0109 Cyanide, ppm 0.01 .0110 Lead, ppm 0.01 .0511 Zinc, ppm 3.00 112 Mercury, ppm 0.001 013 Cadmium, ppm 0.003 .00514 Calcium, ppm 75.00 ----15 Chlorides, ppm 250.00 25016 Fluorides, ppm 1.00 .0817 Nitrate, ppm 4.50 10(5 for cans)23 Total Coli form

Bacteria In 100mlAbsent Nil

24 Plate Count In 1ml,Max

1000 0-15

Note: All parameter of water tested with facilities of in house laboratory and this confirm by third party laboratory test such as SGS, BSTI, BCICR and PepsiCo International approve laboratory.

THANKS