DESIGNING OF WATER TREATMENT SYSTEM

The most important topic that needs to be addressed in an industry is a WATER TREATMENT SYSTEM. I was unaware of many things in this prospective before preparing the site master file for the industry. Its perhaps a long topic to discuss. Nevertheless, the following section consists the outline and a summary of my queries and answers to help understanding the basic design and importance.


Special thanks to,
Bharat kumar pangeni(M. Sc Microbio)
Arun Kumar Yadav(B. Pharm)
Roshan Poudyal(M.Pharm)
Shashikant Chaudhari(M. Pharm)
Saurav Timilsina( B.Pharm)

We use 3 different classes/grades of water in the Pharmaceutical industry:
Portable Water: Directly collected from drinking water source and is meant for drinking and washing purposes. It is generally chlorinated.
Purified Water: This is freed from the microbiological, physical and chemical degradation. For this we use the reverse osmosis and ion exchange system. The Specifications that needs to be met in this class of water are:
S. No. Parameter Unit Limits
1 pH - 5.0 - 7.0
2 Total dissolved Solids ppm Less than 1
3 Conductivity (BP) µs/cm Less than 1.0 at 200C
4 Total Organic Carbon ppb Less than 500
5 Total Bacterial Count CFU/ml Less than 100
6 Coliform CFU/ml 0

Water for injection: Further purification of the purified water by distillation and other means to make it sterile.

EXPLANATION OF THE FIGURE
This is a general description of the figure. It doesn’t hold universal in the purification steps. The complete Purified Water generation system is semi automatic based with individual start stop button on the powder coated and SS 304 control panels.(Just for your information, to test the type of steel we use the SS testing solution, we put a little drops of solution on one part of the steel and connect the part in a battery cell, while the end part of the wire to the part of steel which do not have the solution, if its a SS304 steel, then there is a marked change in color into red or pink type in just 3o seconds, if its a SS316 steel then it takes more than 30 sec, say 30s-1min to change the color) Most of the ancelleries are made up of SS316, SS316 L, Plastic , or even glass channels for the visual transparency.
First the raw water passes to the surge tank(HDPE TANK). The water collects into a ground tank of Higher capacity which is pumped to the tank of slightly lower capacity at the top of the building. The water goes through the series of alum dosing and NaOCl dosing first.(Note that through this dosing, a level of chlorine 0.5 ppm is maintained. The dosing is done in a constant rate through the metering pump(which is a centrifugal pump) which operates only when the main pump operates. Thus treated water is channeled through 2 ways:
1. For the use in canteens, bathrooms, and general purposes
2. For the Pre-treatment

PRETREATMENT
Pre-Treatment is done in order to reduce the particles and impurities so that the Main purification system by the REVERSE OSMOSIS(RO plant membranes) are protected and inorganic and organic particles are removed to a prescribed limits.
The raw water treated with the dosing then passes through the diaphragm valves. Then after the treatment through the sand bed filter, through a multipoint valve. The first sampling point is taken after the sand bed filter. It is applied to SMBS dosing system (Note: Sodium Meta Bi-sulphite dosing is done for the removal of the traces of chlorine which was dosed before for the purification). It then passes through the softner which contains sodium exchange resin that adsorbs the carbonates, sulphates and bicarbonates responsible for hardness of water and then to soft water HDPE tank. Through the series of actuated ball valve and centrifugal pumps, the water then passes over the bag filter(of 5microns pore size and SS 316 housed). Second sampling point is kept after this unit. After the bag filer unit, the water is dosed with antiscalant solution for reducing the silicates.
Main Treatment (The RO system)
Reverse Osmosis Plant treats and removes all the salts up to 99% to give conductivity of <50 μS/cm.For this the treated water is recirculated through a cartridge filter (5 µ) and then through a cartridge filter (1 µ ) which is forced through the RO membranes with the help of a high pressure pump. For this the water has to pass through the low pressure switch, high pressure pump and then to the high pressure switch. The water then passes through the non-return valve. The water then passes through the system of SS 316 RO membrane housing. After the purification steps by the RO system the water passes through the permeate rotameter or the reject rotameter. The permeate water can be put in a loop system in the RO system itself passing through the SS 316 housing filter bag of pore size of 5 microns in a CIP system. The permeate water after the RO is collected in a RO permeate HDPE tank. An important consideration that has to be made in this point is, adjustment of the PH and electrical conductivity after the RO system. PH : 5 – 7 Conductivity : < 1.2 µs/ cm at 25 ° C (Source: IP 97’) Third sampling point is taken after this unit(RO unit). POST TREATMENT In the post treatment unit, the water is purified further by a series of deionizers. The water first passes through the cation unit which is in association with the acid tank and anion unit which is in association with the alkali tank. The water is then purified through the CATPOL unit(it reduces the total microbial load) which is in association with the acid tank. Sampling point can be provided after the CATPOL unit. The water is then passed through the micron filter of 0.2 microns capacity. A sampling point lies immediately after this unit. The purified water is then passed for Ultraviolet Purification. Final collected water can be stored in the storage tank which is a jacketed SS 316 tank having a ball and spray valve. The purified water is kept here at a constant temperature of 80 degrees. Tanks are provided with jacket to maintain water warm or cool. Storage tanks are provided with 'vent'. The vent is fitted with hydrophobic 1 micron air filter to prevent microbiological contamination from outside air. The water is then kept in a continuous loop system through the supply to the production units.

MY QUESTION: How must be the selection of pipes and valves?

SEARCHED ANSWERS:
• SS 316 or SS 316 L type of stainless steel material must be used. They are inert to a wide ranges of temperature.
• Sometimes when ambient temperature is required, plastic pipes may also be used. Sometimes when transparency is required, glass pipes may be used. But important factor to be considered is that only SS 316 and SS 316 L type of material is used after the deionizer.
• Stainless steel must be Orbital or TIG welded and each weld must be visually inspected or baroscoped and documented.
• The pipes must not be longitudinally placed as far as possible because there is a high chances of microbial proliferation through stagnance of water layer. Slant designing of pipelines is favoured. • Welding process should be Orbital or TIG welded. The efficiency of the welding can be determined by the validation by visual observance or baroscopically determined.
• Gate, ball, butterfly, diaphragm - type valves are used in water treatment system. But for the deionizer system and the RO system, diaphragm type of valves are used because these valves are easy to clean and sanitize.
• Sometimes, as a sterilizing agent OZONE is used. An important point to be considered is that it is as a very degradation potential. So, TEFLON is used here, TEFLON doesn’t degrade in the repeated application of OZONE.

MY QUESTION: WHAT ARE THE CONSIDERATIONS TO BE MONITERED IN THE FILTRATION MEDIA?

SEARCHED ANSWERS:
For membrane Filters/ cartridge filters

• Filters can become damaged by frequent or sudden changes in water pressure. So, an ambient pressure should be maintained.
• Checking compatibility of membrane material with sanitizing agents,
• Checking membrane integrity and seal integrity.
• Checking fouling by particles and microorganisms For depth filters like sand filter:
• To check channeling of filtering media- Pressure and low flow monitoring.
• To check blockage from slit, microbial growth- Sanitization and replacing of the filter media

MY QUESTION:What can be done to reduce the COST (Taking in consideration of small production industries like in Nepal?

SEARCHED ANSWERS:
These are some of my points I thought to work to minimize the cost and proper operation in small industries. Otherwise the steps in the purification can’t just be neglected.

1. The above explanation is the practice of the general pharmaceutical industries of Nepal. CATPOL unit is only placed in some industries and is a costly system. This enhances the purification even more but the purification can be done in parts well even by passing through the ion-exchangers only.

2. It is wise to put the sampling points after each purification units in order to know the point of defect in the purification system.

3. When the analysis of water is done the usual practice is the analysis of the final treated water only. Periodic validation of the process of checking and the quality of water must be done. The point holds even more strong for the protection of the RO units which consists of RO membranes having a high chances of damage if pre-treatment is not good. Hence a sampling unit immediately before the RO unit (Keeping the range of impurities that can be allocated) can be provided. The validation must be done at proper time intervals.

4. The problems with the mixed bed resins is the precipitation of resins. Periodic evaluation for the purity of water keeping a sampling point through the resin should be done. This enhances the protection to the disc and membrane filters.

5. Aeration of the water (simply for the precipitation of iron and oxides should be done ). When iron gets oxidized it sediments at the bottom. This system should be followed before other dosing steps.

What are the different kinds of problems that we encounter in the piping system and how can we check them?.......................Gunjan K. Subedi

Encrouchement- In this type of most common problem that we see in piping, there is the gouging and denting. The gouging creates a very low barrier to the start of the crackling because it creates a local hard and brittle surfaces. On the other hand, denting creates local areas of very high strain. Dent is not a very big problem, if the dent is uniform and the pressure drop is also uniform. Weather related- Another type of source of crackling of the pipelines is the weather related issue such as heavy rainfall, snowfall, movement of the earth(eg, earthquake which can damage the piping inside the surface of the earth, Lightning etc which can cause the pipes initiate to crack.

COROSSION

1. Holes(SELF GIVEN NAME)- This is a type of coating problems where there are small separated spaces in the coating of the pipe lines. The moisture can easily enter inside the holes and due to the permeability problems, a layer of the coating can further scrub off.

2. Inadequate cathodic protection

3. Stress-corrosion crackling- In this type of crackling, there is a combined stress+holes(causing permeability of the moisture and inadequate cathodic protection. This is more seen in the pipelines that carry the carbonates and bicarbonates system. Here, The Ph of the system is around 9. The crackling can start from the minor intergranular crackling to a big fracture in the pipeline.

4. Hydrogen Stress crackling- In this type of crackling, in the local had surfaces of the pipes having a hardness of greater than 350 brinell, the metal starts to absorb hydrogen in advance to the cathodic protection.

5. Internal gaseous corrosion (SELF GIVEN NAME) The most common corroding agents in the pipelines are the Oxygen, Hydrogen Sulfide, and carbondioxide. Oxygen is one of the major sources of corrosion. Both H2S and CO2 are acidic, the combination is even more acidic in the piping system where both of these agents flow. Hydrogen Sulphide caused corrosion creates a corrosion in the steel which generates the Hydrogen atom. The two hydrogen atom makes a hydrogen molecule. The thing to be noted is that the space that Hydrogen molecule takes is higher then the space that combination of two hydrogen atom takes so there is marked Increase in the pressure. It causes the initiation of the crackling. Another problem is that due to the debris and the film layer, micro-organisms can accumulate. One form of the MO, ie, sulfur reducing bacteria can generate the Hydrogen atom from the hydrogen sulphite. The generation of the hydrogen creates a chain of reation causing the damage as explained above. One thing to be noted is that only wrought iron is induced to this sort of stepwise H2S and CO2 induced crackling system. Casting and welds do not have these sort of problems.

MY QUESTION: How can we prevent the piping problems by lamination, what are the laminating agents?

SEARCHED ANSWERS: The lamination in the QMed used the colored cotton(insulating material covered with a wire gauze and kept in safe by the aluminium sheets. When I searched over the net, I found basically 6 types of insulaing agents based on the service they provide:

• Hot insulation- That prevents from the transfer of the heat from the pipeline to the surrounding.

• Personal prevention insulation- That protects a person from the shocks of heat and electricity

• Cold insulation- That are used in the chillers

• Anti-Sweat Insulation- That prevents the moisture from getting contact with the pipelines

• Acoustic insulation- Eg in the HEPA filter lines that protects from the generation of the sound

• Heat tracing insulation- Sometimes heat tracing elements are used around the pipeline surfaces. This type of insulation prevents both the heat tracing element and the pipe temperature.


MY QUESTION : What are the types of materials used in insulation?

The basic mechanism in the insulation is that there are various void spaces of the air(note:stagnant air is a bad conductor of heat.) inside the network of the insulating fibres. Basically two types of materials are use in insulation.

Fibrous material- Which have a very large void air spaces in between them. Such as- cork, glass wool, mineral wool etc.

Cellular material- Which have very small but close void spaces in between them such as polyurethane, polystyrene, calcium silicate, etc

QUE: How is insulation done?

Pipe-inulation inner layer-sealent-insulation outer layer-vapour barrier- Gi sheet, aluminium sheets

What are the things to be done in validating the water treatment system? What is the importance of water treatment sys validation?

STEP 1>DESIGN AND INSTALLATION REVIEW

The first important thing in validation of water treatment system is a design and installation review. After the installation of various parts of the water treatment system an up to date description and design drawing should be done. This design drawing should include all the components of system and sampling points should clearly be defined in it. It is advisable to review the design drawing annually to ensure that it is accurate and up to date. These reviews often identify unreported changes and are effective in confirming reported changes to the system.

STEP 2> DEVELOPMENT OF SOPS
Develop the operational parameters and cleaning and sanitizing protocol. Once the parameters are defined it will be easy then to develop the SOPs. Data are then collected over a period of two to four weeks, and samples should be collected daily after each purification step and from all points of use. At the end of the period, if the system has successfully generated water of the appropriate quality, these procedures are established as the water system’s SOPs.

STEP 3> DEMONSTRATION OF EFFECTIVENESS
In this phase of the validation we have to demonstrate that when each procedures of the SOPs are followed, a purity of water as defined in the specification are met. This type of operation should identify any inconsistencies in the feedwater quality due to seasonal variations or other changes in the quality of the source water. A water system cannot be considered validated until the manufacturer has a year’s worth of operational data.

STEP 4> DATA COMPILATION

The final step involves combining the data in the final report. Once the final report is complete, it is important to ensure that the appropriate personnel review and sign off on it.

What are the important things to be considered in validating a water system?
1. FEEDWATER
 Give consideration to the quality and seasonal variation of the feed water.
 Consider the quality of water in surrounding municipalities in the event that water must be diverted from an alternate, neighboring source. For example, take the consideration of QMed Formulations if the water it takes from lease is found to get infected constantly by the coliform outside the limits its wise to change the source rather than using the same for the treatment system.
2 Air contamination.
 The SOPs should be reviewed to ensure that proper valve sequencing prevents contamination from non-sterile air.


3. DESIGN
DESIGN OF THE CARBON BEDS-
 Carbon beds filter the organic material needed for bacterial growth, this material becomes concentrated in the carbon beds; if the beds are not properly maintained, they can harbor bacteria and endotoxins. Hot water or steam should be used periodically to purge the system of such contaminants.
 It is important that the SOPs include these maintenance procedures.

4. HOLDING TANKS-
 Most new tanks(I am not sure of the practice in Nepal’s pharmaceutical industry) utilize jacketed vent filters to prevent condensate or water from blocking the hydrophobic filter. Maintenance SOPs include procedures for regular checking of the vent filter integrity.
 The filter should be located in a position that provides easy access for testing.
 The SOPs should also include complete flushing or draining of the holding tanks on a regular basis.

5. HEAT EXCHANGERS

 They should be designed to prevent distillate contamination from feedwater. Double tubesheet design and positive pressure are the two most common methods used.
 If positive pressure is utilized in the design, monitoring systems should ensure that higher pressure is constantly maintained on the distillate side.

 It is important that the condenser be designed with double tubesheet to ensure that the distillate will not come in contact with the coolant, thus preventing recontamination

6. PUMPS
 Focus should be given in maintenance SOPs.
 If a pump is not in continuous operation, the reservoir is a potential source of contamination; when the pump is not in use, water may collect in the low point of the pump housing, potentially harboring microorganisms. It may be advisable to install a drain in the low point of the pump housing.

7. PIPING

 Where low level metal contamination is a concern, polyvinylidene fluoride (PVDF) piping should be used in place of the SS piping. Systems utilizing PVDF piping, however, require additional support in the piping layout. While the system is in use, the circulation of hot water may reduce the rigidity of the piping, causing it to sag. In cases where the piping sags or bends, stress can create fissures in joints, which may result in leakage and/or contamination.
 Consideration on the elimination of “dead-legs” and the use of welding or sanitary fittings for all joints and connections in the system design should be done.

8. MICROBIAL LIMITS

In WFI systems it is possible that a system may pass either the microbial or endotoxin action limit but fail the other. It is therefore import that both endotoxin and microbial levels are closely monitored.

When alert and action limits have been established, we have an SOP for investigating deviations.

9. COST OF OPERATION