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Twenty-first International Water Technology Conference, IWTC21 Ismailia, 28-30 June 2018

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EFFECT OF TREATMENT ON PRODUCTIVITY AND QUALITY OF PURIFIED

WATER SYSTEM USED IN PHARMACEUTICAL APPLICATION

Farrag, T.E1., and Abdelbasier A.M

2.

1 Chemical Engineering Department, Faculty of Engineering, Port Said University, Port Said, Egypt.

2 Chemical Engineering Department, High Institute of Engineering & Technology (Tanta), Egypt,

E-mail: [email protected]

ABSTRACT

A good quality pre-treatment process is instrumental to the successful operation of a purified water

system in pharmaceutical plant. WHO guideline (TRS 970A ) strongly recommended that the production

of water for pharmaceutical use, must always start with potable water. The compounds that are

susceptible to foul the reverse osmosis (RO) membranes may beplagued with impurities ofinorganic

suspended solids, sand, oil, clays, bacteria, and dissolved organic matters in feed of potable water. Those

impurities can effect on productivity of RO which is the main represented parameter can measure the

overall performance of the purified water system quantitatively. This study was carried out on purified

water system of Alkan Pharmaceutical (now – Hikma pharma) industries located in industrial zone of 6th

October city. The main objective of this research was to investigate the effect of pretreatment steps using

different disinfectants (NaOCl, H2O2), the position of injection port of Sodium Meta Bisulfate (SMBS -

(5%)) before and after depth filter onthe microbial contamination results. Results showed that the effect of

sodium hypochlorite (30 ml/hr) on disinfection yield microbial count lower than the USP Alert limit (300

CFU/ml) for more than 140 days after system start up, while hydrogen peroxide failed after 80

days.Finally, if a water purification system is designed, operated, and maintained properly, it should not

be plagued by microbial contamination. However, if special attention is not dedicated to the control of

microbial growth, problems will very likely result in less productivity of purified water system.

Keywords: purified water; pharmaceutical water system productivity;microbial effect; injection of

(SMBS)

1 INTRODUCTION

Generally Purification of water from its contaminants, physical, chemical and biological contaminants

is the principle of water purification process which treats practical, salts and organism growth in the

economic sense, In fact, the goal of water treatment process is to remove existing contaminants in the

water meanwhile the pretreatment stage enhances and improves the service life of the principle

purification equipment. Large quantities of impurities is the main problem for Pre-treatments generally

deal with.

Pre-treatment steps are unit operations and unit processes employed prior to removal of different

materials. Primary types of pretreatment units include multimedia filtration, activated carbon units,

chemicals injection units and water softening units. A devolvement of some effective component is

presented. Design, operation, selective proper position, and validation of operating data are also

investigated. There is no unique pre-treatment process that is suitable for all industries requirement. In

those industrial-scale processes water treatment describes water systems more acceptable for a desired

end-use. These can be used for drinking water, industry, medical and many other uses. The processes

involved in treating water for drinking purpose may be physical processes such as settling and filtration

to treating solids separation, and chemical processes such as disinfection and coagulation.

mailto:[email protected]


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1.1 Water Impuritise.

The feeding raw water varies in quality from one geographical source to anothersuch as river, well,

orlake, Its chemical and physical make-up is very site specific in that it reflects the local geology and

topography as modified by human activities, such as housing, agriculture, and industry. Raw water

contains variously leached and dissolved materials and salts. For example runoffs or streams have picked

up various impurities, including organic materials such as, salts, colloids, and various other soil

constituents. Natural waters also nurture organisms such as bacteria and viruses [1]. The major

categories of impurities found in raw water include;-

• Suspended particles

Colloids

Micro-organisms

• Dissolved inorganic salts

Dissolved organic compounds

• Pryogens

• Dissolved gasses

For instance, water derived from asurface source like rivers usually has a low Total Dissolved Solids

(TDS) content, but a high concentration of organic contamination. It is also consider as soft water due to

hardness ranged from 10 to 50 ppm. But water derived from an underground source like wells generally

has a high TDS content, but a low organic content. It is also has a high hardness level . Due to this raw

water quality variety, the different methods of treatment and a lot of equipment are necessary to convert

natural water to purified water is all site specific [2].Surface water contains anassortment of organisms

including bacteria, paramecia, and algae. Most of microorganisms are kept at low levels by the

introduction of chlorine or disinfectants, however once these disinfectants are moved in the purification

process, the microorganisms are again free to grow. So that bacteria are the main microorganism that are

of concern in water purification systems. Silt, suspended particles, and colloids are suspended matter in

raw water includes [3]. Colloidsare particles that are not truly in solution or suspension, and they may

give rise toturbidity. Total suspended particles can block membranes as ultrafiltration and reverse

osmosis and alsointerfere with the operation of pipes and units.

1.2 Pharmaceutical water types.

The United States Pharmacopoeia Convention (USPC) is a private non-profitorganization that sets the

guidelines for manufacturing drugs, medical devices and diagnostics throw a standard called cGMP

(current good manufacturing practice). USPC sets the standards for purified water in the pharmaceutical

industry [4]. The USP defines several types of water including; Purified water (PW), Water for

injection(WFI),Sterile water for injection, Sterile water for inhalation, and Sterile water

forirrigation.However there are two basic types of water preparation (PW, WFI) must pass a bacterial

endotoxin test. these two waters are quite similar, exceptfor WFI has more strict bacterial count

standards of maximum allowable 10 cfu/100 ml of water for injection sample,but purified waterhas a

standards of maximum allowable 100 cfu/1 ml.

1.3 The problems facing production of the purified water system.

A lot of problems face purified water generation output and also quality wise , The escaping of

suspended matter (≤ 90 µm) from the depth filter of 90 µm and 200 µm. and High temperature of the

feed water (city water) leads to increase the conductivity of purified water more than 1.3 µS/cm (limit of

USP specification).also water filtrate tank is made of st.st. which is corroded by free chlorine present in

the water produced from the ultrafiltration unit.The low st.st. Tank capacity cause sudden shut down of


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the washing and rinsing facilities of the softener and R.O units. It was found that the two depth filters of

1 µm and 5 µm increase the ability of the microorganism growth.The injection of sodium bisulfite

(NaHSO3 5%) (Chemicals used to remove the residual of free chlorine) before the depth filter increase

the chance of microbial safe growth.result in Low productivity of the R.O. membranes from 1000 l/h

decreased to 800 l/h in few months due to rapid biofouling of R.O. membranes.

2 MATERIALS AND METHODS

2.1 Description of the existing purified water system of Alkan Pharma

The new technology used in the Alkan Pharma Company was as investigated below, The first part

(pretreatment part before modification) is shown in flow sheet in figure 1 it consists of the following units

;Chlorine injection (sodium hypochlorite 12 % free chlorine) for disinfection of the raw water feed (city

water). Two depth filters of 200 µm and 90 µm are used to remove the suspended matter more than 200

and 90 µm.The storage tank of raw water with capacity 1100 liters. Ultrafiltration units for removing the

suspended solid in the feed water[5]. The storage tank for the filtrate water (water produced from the

ultrafiltration unit) made from st .st. material .The tank capacity is 1000 liters.Softeners (two columns of

softeners working in series) are used for softening filtrate water from 150 ppm to ≤ 5 ppm as

CaCO3.Injection of sodium bisulfite (NaHSO3 – 3 % concentration ) .Two depth filters of 5 µm and 1 µm

used to protect the Reverse Osmosis from suspended matter less than 90 µm and more than 1 µm. One

passes reverse osmosis membranes used for desalination of the softened water from 220 ppm as TDS

(total dissolved salts) to ≤ 10 ppm.Electrodioniser ( EDI ) used to complete desalination of the water

produced from R.O. membranes of TDS ≤ 10 ppm to purified water in ≤ 1.3 µS/cm as requirement by

United State pharmacopeia 2004

2.2 Water Sample.

A physical , chemical and microbial testing of samples was carried out on laboratory of Alkan Pharma

Company, samples was taken from the purified water system of model (Christ – CWD70880A) (case

study) located in the same company, that systemwas used for all experiments in this study. The location

of samples port are shown in Fig1, 2.

Figure1. Pre-treatment section of purified water system (case study) before modification.


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All samples used were taken from the factory raw water and purified water. The following table (1)

shows the standard limits specification by National Testing Laboratories, Ltd 1995.

Table 1. the standard limits specification of raw water and purified waterAccepted criteria form (United

States Pharmacopeia 27, (2004)

Test type Test item Specification of raw

water

Specification of purified

water

Physical Appearance. A clear, colorless

odorless and

tasteless.

A clear, colorless odorless

and tasteless.

Chemical FREE CHLORINE 1 : 1.5 ppm zero

Chemical pH 5.0 – 8.0 5.0 – 7.0

Chemical Total solids Less than 15 % N.M.T. 0.001 %

Microbial Total bacterial count Less than 500

cfu/ml

Less than 100 cfu/ml

Figure2. Pre-treatment section of purified water system (case study) after modification.

2.3 Experimental Setup and Procedure of physical and chemical tests.

2.2.1.Appearance

A clear, colourless odourless and tasteless: By analyst eyes


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2.2.2 Free chlorine

Using colorimeter free chlorine test kits, add 3 drops of reagent number 1 then mix and add 5 drops

of reagent number 2. Compare the color on sample and on the reference sheet

2.2.3pH

Using pH meter, clean the probe before using by distilled water and immerse theprobe on sample

container then slightly mix is required to get the fixed value of pH that appear on the meter display

screen.

2.2.4 Total solids

Evaporate 100 ml of the sample on a steam bath to dryness in a crucible and dry the residue at 105°C

for 1 hour, cool to room temperature in a dessicator and weigh. (Wang, S.1981).(g of residue x 100) /100

ml = % Total solids (w/v)

2.4 Equipment used for chemical and physical tests.

pH meter

Manufacture: Jenway .Serial no.: 1635

Free chlorine test kit

Manufacture: Hanna. Serial no.:HI3831F

Water bath

Manufacture: Clifton. Serial no.: 23398

Desiccator

Manufacture: MIA. Serial no.: De.112/14s

Analytical balance

Manufacture: Mettler Toledo. Serial no.: 1122443482

2.5 Microbiology test

2.5.1 Sampling

Sampling Containers. Sterilized glass or pre-sterilized plastic bottles capable of holding minimum 500

ml volume. Bottles may only be reused if they are re-sterilized [6]

Sampling collection:

A) Wear powder free rubber gloves when collecting samples. Wipe gloves with an

approved sanitizing agent (IPA 70%) prior to collecting each microbial sample.

B) Wipe or spray exterior of the sample site with an appropriate sanitising agent such

as 70% isopropyl alcohol, 70% ethanol …etc. wipes should not be particle shedding

materials. Allow the port to dry.

C) Flush the outlet for not less than 3 min, flushing time for sampling should not exceed

the flushing time for normal use.

C) In case of more than one sample type to be collected for more than one test, collect

microbiological samples first to ensure that the total count results reflect actual use conditions

as closely as possible.


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2.5.2 Testing procedure

Total viable count:

-Filter 100 ml of the water sample through a membrane filter [7].

-Rinse with phosphate Buffer pH 7.2 when bactericidal substances are suspected to be present,

and place the filter on a TSA (tryptic soya agar) plate (Shaw, 1986).N.B. For samples that

historically count more than 200-300 organisms per 100 ml i.e. (high total bacterial count)

HTBC/100 ml (also for those samples expected to have this count) ,1.0 ml & 0.1 ml of the

original sample are to be tested -instead of testing 100 ml.

For accurate countable results by one of two ways: -

1- Pipette directly 1.0 ml & 0.1 ml of the submitted sample into each of two petri dishes and add

15 ml of melted TSA (tryptic soya agar) at 45 ºC (pour-plate method).

2- Filter 1.0 ml & 0.1 ml of the submitted sample each through a membrane filter,rinse with

phosphate buffer,then place each filter on TSA (tryptic soya agar) plate (membrane filteration

method- Singh, J.,1999).

3- Incubate at 30-35 °C for a minimum of 5 days (European requirements), unless reliable count

is obtained in a shorter period.

Negative control: 100 ml of sterile phosphate buffer should be filtered as the above procedure

before tested sample is processed.

2.5.3 Equipment for microbial tests

Water bath with shaker.

Manufacture: Clifton Company, Serial no.: 23309

Oven.

Manufacture: Selecta Company. Serial no.: 0500824

Incubators: 30-35, 37 ± 1°C.

Manufacture: Gallenkamp Company .Serial no.: SG97/11/346

pH meter.

Manufacture: Jenway Company. Serial no.:1635

Filtration unit (manifold, Büchner, Vacuum pump, Membrane filter 0.45 um )

Manufacture (Vacuum pump): Laboport Company. Serial no.: 20589144

Sterile pipettes 1, 2, 5, 10 ml.

Manufacture: MK Company. Serial no.:325-2006p

Sterile disposable petridishs.

Manufacture: PETRI Company .Serial no.: P-500

Disinfectant (ethanol 70 % or IPA 70 %)

Manufacture: Merk Company. Serial no.:Lot12/50

Bunsen burner.

Manufacture: Bunsen Company, Serial no.:POI70/118

Culture media and Buffer.

Manufacture: Difco Company .Batch no.:07581920

3 PROCESS MECHANISM

Regarding to the main objective of this study, process mechanism explain the effect of using different

disinfectants (NaOCl, H2O2), the position of injection port of sodium metabisulfite (SMBS - (5%)) before

and after depth filter on the microbial contamination results also on overall productivity of the generation

system of purified water [8].


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3.1 Effect of particle contamination of raw water on microbialcolonization growth.

1-Installing two depth filters of 25 µm in city water stream line to remove the suspended matter less

than 90 µm.One concern with using pre-oxidants for disinfection is that particulatematerial may interfere

with microbial inactivation [9]. Such material protectsbacteria and viruses from disinfectants by creating

an instantaneous disinfectantdemand (preventing the maintenance of a disinfectant residual in

subsequenttreatment steps) and by shielding the microbe from the oxidant.

Figure 3.physical Relation between Suspended particles and bacterial cells in pipe

3.2 Chemical Injection of Reducing Agent (SMBS).

Chemical injection of reducing agent such as sodium bisulfite may be employed in lieu of activated

carbon units for ground water supplies not influenced by a surface water supply and with low TOC

concentration[10]. A positive displacement pump, chemical storage tank, injection device with mixing

capability, and post injection online oxidation-reduction potential (ORP) monitoring system are required.

Reducing agents can introduce significant amounts of bacteria if the system is not designed properly or if

freshly prepared reducing agent is not used.Residual free chlorine can be reduced to harmless chlorides by

activated carbon orchemical reducing agents[11]. An activated carbon bed is very effective in the

dechlorination ofRO feed water according to following reaction:

C + 2Cl2 + 2H2O → 4HCl + CO2 (1)

Sodium metabisulfite (SMBS) is commonly used for removal of free chlorine and as abiostatic. Other

chemical reducing agents exist (e.g., sulfur dioxide), but they are not ascost-effective as SMBS.When

dissolved in water, sodium bisulfite (SBS) is formed from SMBS:

Na2S2O5 + H2O → 2 NaHSO3 (2)

SBS then reduces hypochlorous acid according to:

2NaHSO3 + 2HOCl → H2SO4 + 2HCl + Na2SO4 (3)

In theory, 1.34 mg of sodium metabisulfite will remove 1.0 mg of free chlorine. In practice,

however, 3.0 mg of sodium metabisulfite is normally used to remove 1.0 mg of chlorine[12].

Inlet of raw water

Suspended

Particles load

Cell load

Nutrients load

Water outlet

Suspended Particles

load

Cell load

Nutrients load

Cells

Particles

Cells Cells

Cells

Pa.=(Cell+Nu.)

Adsorbe

d

Consumed

Nu.

Nu.


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3.3 Bacterial Disinfection Mechanism.

3.3.1. Chlorine disinfection mechanism.

Further work led to the so-called "multiple hit" theory of chlorine inactivation. It asserted that bacterial

death probably results from chlorine attacking a variety of bacterial molecules or targets, including

enzymes, nucleic acids and membrane lipids[13].

possible sequence of events during chlorination would be:

1 Disruption of the cell wall barrier by reactions of chlorine with target sites on the cell surface

2 Release of vital cellular constituents from the cell

3 Termination of membrane-associated functions

4 Termination of cellular functions within the cell.

Some additional details are provided by Leslie E. Dorworth of the Illinois-Indiana Sea Grant College

Program,regulation that would reduce the chlorine concentrations in drinking water to assure that the

disinfectant does not approach unsafe levels. THM is a byproduct may formed in the reaction between

hypochlorite with organic in water disinfection phase[14].

Chlorine demand = chlorine consumption + desired residual……. eq.4

Chlorine kills pathogens such as bacteria and viruses by breaking the chemical bonds in their

molecules. Disinfectants that are used for this purpose consist of chlorine compounds which can exchange

atoms with other compounds, such as enzymes in bacteria and other cells. When enzymes come in contact

with chlorine, one or more of the hydrogen atoms in the molecule are replaced by chlorine[15]. This

causes the entire molecule to change shape or fall apart. When enzymes do not function properly, a cell or

bacterium will die.

When chlorine is added to water, underchloric acids form:

Cl2 + H2O -----> HOCl + H+ + Cl- (5)

Depending on the pH value, underchloric acid partly expires to hypochlorite ions:

Cl2 + 2H2O -----> HOCl + H3O + Cl- (6)

HOCl + H2O -----> H3O+ + OCl- (7)

This falls apart to chlorine and oxygen atoms:

OCl- ----> Cl- + O (8)

Underchloric acid (HOCl, which is electrically neutral) and hypochlorite ions (OCl-, electrically

negative) will form free chlorine when bound together. This results in disinfection. Both substances have

very distinctive behavior [16]. Underchloric acid is more reactive and is a stronger disinfectant than

hypochlorite. Underchloric acid is split into hydrochloric acid (HCl) and atomair oxygen (O). The oxygen

atom is a powerful disinfectant.The disinfecting properties of chlorine in water are based on the oxidizing

power of the free oxygen atoms and on chlorine substitution reactions[17].The sum of Cl2, NaOCl,

Ca(OCl)2, HOCl, and OCl– is referred to as free available chlorine(FAC) or free residual chlorine (FRC),

expressed as mg/L Cl2. As discussed later,chloramines are formed from the reaction of chlorine with

ammonia compounds present inthe water[18]. These chlorine-ammonia compounds are referred to as

combined availablechlorine (CAC) or combined residual chlorine (CRC). The sum of free and

combinedavailable/residual chlorine is called the total residual chlorine (TRC).


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TRC = FAC + CAC = FRC + CRC (9)

3.3.2. Hydrogen peroxide disinfection mechanism

All bacteria and viruses are composed of carbohydrate, protein, RNA and DNA. For structure of

protozoa and bacteria, all cell organs are surrounded by cell wall and cell membrane Ozone molecules in

ozonized water has high oxidation potential and it oxidizes cell components of the bacterial cell envelope

which is a consequence of cell wall penetration. When ozone has entered the cell, it oxidizes all essential

components (enzymes, proteins, DNA, RNA). This mechanism differs from that of halogens (such as

chlorine), which are usually applied. Chlorine is known to penetrate cells by diffusion[19]. Within the

cell, chlorine affects several enzyme types.Pollutions are decomposed by free oxygen radicals, and only

water remains. Free radicals have both oxidizing and disinfecting abilities [20]. Hydrogen peroxide

eliminates proteins through oxidation. Peroxides such as hydrogen peroxide (H2O2), perborate,

peroxiphosphate andpersulphate, are good disinfectants and oxidisers. In general these can adequately

remove micro-organisms. However, these peroxides are very unstable.

3.3.2.1 Free Radical formation and Fenton reaction

The mechanism of cytotoxic activity is generally reported to bebased on the production of highly

reactive hydroxyl radicalsfrom the interaction of the superoxide (O2+2

) radical and H2O2,a reaction first

proposed by Haber and Weiss (eq. 10):

H2O2 -------> H2O +O2 (10)

A reaction first proposed by Haber and Weiss (eq. 10). Hydrogen peroxide is used as a disinfectant and

will disintegrate into hydrogen and water, without the formation of by-products, the disinfection

mechanism of hydrogen peroxide is based on the release oxygen radicals.

4 RESULTS AND DISCUSSION

The efficiency of Reverse osmosis membranes(R.O)is the main factor effecting on the overall

production of purified water system and strongly illustrated on both productivity and water quality of the

system output. The work of this research aim to enhance the lifetime period of Reverse osmosis

membranes and generally improvement of cost reduction of overall plant operationally. This study

investigate the direct effect of using different disinfectants sodium hypochlorite and hydrogen peroxide

on removal of bio-pollutants in pre-treatment (located before RO) onproductivity of the R.O. membranes,

also the effect of proper position of the injection of sodium metabisulfite.

4.1 Effect of Bacterial Disinfection in pretreatment section on RO productivity.

4.1.1 Effect of using disinfectant Sodium Hypochlorite (NaOCl, conc. 12%).

The plots of Fig.4 demonstrate how the quality of water has changed within 80 days. Different flow

rates of200, 300 and 400 ml/h of injection sodium hypochlorite application in the investigated methods of

disinfection pretreatment. As shown by these data the microbial count was observed to be 291 CFU /ml

which near to be out of standard limit of 300 CFU /ml within 37 days. Meanwhile 80 days consumed in

safe limits at using 300 and 400 ml/hr.


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Figure 4. Effect of different sodium hypochlorite flow rate (20, 30 and 40 ml/hr.) on microbial count in the

Ultra filtration unit (UF).

The explanation of the data plotted in Fig.4 has to be sticky for the stop and alert limits of microbial

count USP standard 500 CFU/ ml, and 300 CFU/ml respectively. Generally this study is an attempting to

determine the suitable dosing rate of proper disinfectants. Experiments curried out of increasing the

dosing flow rate of the sodium hypochlorite to 400 ml/hr was comparing with results obtained at flow rate

of 300 ml/hr. the fig. 4 shows within 70 days dosage rate of 300 ml/hr is safe and chosen as to be the

optimum dosage rate.

4.1.2 Effect of Hydrogen peroxide ( H2O2).

Three dosage rates of hydrogen peroxide (200, 300and 400 ml/hr.) at bulk concentration 50 % v/v,

were studied for disinfection of pretreatment units. Fig. 5 shows that results of microbial count after using

Hydrogen peroxide (200 ml/hr of concentration 50% v/v) as disinfection medium, 56 days was the period

at water contaminated with bacteria at 300 CFU/ml. The results of microbial count of the sample which

was taken after the UF unit, shows that the maximum value of microbial count was observed after 63 days

in case of 300 ml/hr dosing rate. Meanwhile the maximum period 77 days wasachieved at dosing rate of

400 ml/hr of hydrogen peroxide at bulk concentration of 50 % v/v.


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Figure 5. Effect of Hydrogen peroxide (conc. 50% v/v) of flow rate doses (20, 30 and 40 ml/hr) on microbial

count.

4.1.3 Comparison between two disinfectants used (Sodium Hypochlorite, NaOCl & Hydrogen

peroxide, H2O2)

Figure 6 shows the collective values of microbial count as a result of injection by sodium hypochlorite

300 ml/h and that of the hydrogen peroxide at same dosing flow rate. the collective data were plotted in

fig. 6 to illustrated the proper selection respected to water quality and economics point of view. The effect

of sodium hypochlorite (300 ml/hr.) on disinfection yield microbial count lower than the USP Alert limit

(300 CFU/ml) for more than 80 days after system start up, while hydrogen peroxide failed after 66 days.


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Figure 6. Effect of both sodium hypochlorite (12 %) at 300 ml/hr. versus hydrogen peroxide (50%) at 400

ml/hr. dosing rate for disinfection of Ultra filtration unit

4.2 Effect of injection position (before and after depth filter) of SBS (Sodium bisulfite

NaHSO3, 5%) on Productivity of RO.

The normal position for injection of SBS as pre installation, was before the depth filter (5 µm) this

position of injectionallow the water to pass into the depth filter without free chlorine (1ppm of free

chlorine was removed by adding 150 ml/hr. of sodium bisulfite NaHSO3 5% ). The monitoring data of

microbial count of that injection before depth filter & injection after depth filter was illustrated in the

following figure 7.

The results in Fig. 7 shows that the microbial count in case of the injection of sodium bisulfite before

the depth filter, Themaximum value of microbial count was found after 14days of 302 CFU/ml, that is

more than the USP Alert limit of (300 CFU/ml).The results in Fig. 7also shows that microbial count in

case of the injection of sodium bisulfite after the depth filter. Where the highest value of microbial count

was found after 77 days 220 CFU/ml which is below the Alert limit of 300 CFU/ml. It’s clear that

position of injection after depth filter is the preferable that that position before.


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Figure 7. Effect of changing the injection position of SBS (sodium bisulfite, 5%) of dosage flow rate 150

ml/hr. (before and after the filter) on microbial count.

4.2.2 Effect of microbial results on the Water productivity (Q) at different injection

position of SBS (5%).

The productivity flow rate (Q L/hr.) of the purified water system (reverse osmosis membranes

productivity) according to the direct effect of changing the injection position of SBS is illustrated in the

following Figures 8, 9.

Figure 8. Effect of microbial count on the water

productivity (Q) at position of injection of SBS (5

%), before filter.

Figure 9. effect of microbial results on the

productivity (Q) at position of injection of SBS (5

%), after filter.


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The designed value of reverse osmosis output is 1000 L/hr. The productivity of RO membranes is

affected negatively from 1000 L/hr to 851 L/hr due to microbial bio-fouling. The flow rate decreased 15%

of the designed valueas an effect of the injection of SBS before the depth filter.

Fig. 9 shows that positive effect on the productivity of RO membranes by the injection of SBS after the

depth filter (the designed value is 1000 L/hr) the flow rate decreased to 991 L/hr in 35 days and the lowest

value of 950 L/hr was observed after 77 days,the productivity was decreased by 5 % of the designed

value.

Figure10. Effect of microbial results on the productivity (Q) at different injection positions of SBS (5 %).

Fig 10 shows the effect of microbial count due to changing the position of injection point of sodium

bisulfite NaHSO3 (5 %, 150 ml/hr ), which is used to remove the residual free chlorine to protect the

membranes of Reverse Osmosis. it was noticed that the reduction of the microbial count is better when

position of injection SBS is after the filter i.e there is decreasing infection by biofouling on the

membranes surface and we can keep the productivity of water near to the designed value of 1000 L/hr.

5 CONCLUSIONS

Study resulting in some modifications to solve the previous problems, refers to the modification flow

sheets pretreatment fig.2.Sodium hypochlorite at dosing rate of 400 ml/hr. Change the Injection of sodium

bisulfite to be after the depth filter (instead of before) allowing the free chlorine to attack the

microorganisms present in the pores the depth filter. That modification result in keeping the system away

far from bio-attacking of the microorganism from the R.O. membranes make the membranes in 1000 l/h

as designed Keeping the system away far from bio-attacking of the microorganism from the R.O.

membranes make the membranes in 1000 l/h as designed, Finally, if a water purification system is

designed, operated, and maintained properly, it should not be plagued by microbial contamination.

However, if special attention is not dedicated to the control of microbial growth, problems will very likely

result. The current (USPXXII) specifications for USP Purified Water have established a limit for

microbial concentration. In both cases gives a "recommended action limit" of 500 colony-forming units

per milliliter (CFU/ml) for the feed water and the minimization potential for microbial contamination of

pharmaceutical water systems, is followed through the design, operation, routine monitoring and analysis


292

are the critical elements to control the microbial count. A sanitization schedule should be established in

early stages and, evaluation of microbial count for effectiveness of the process

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