START UP AND SHUT DOWN PROCEDURES
9.1 START UP PROCEDURES
9.1.1 General Start-Up Procedures
The following points are checked at each start-up, after the initial commissioning start- up carried out by
Carry out an initial disinfection of all structures (shock chlorination) as follows:
According to American American Water Works Association (AWWA) standards one of the following two methods can be used for initial disinfections:
• Residual method: Fill the structure with water to sufficient chlorine (Javel water or chlorine if this can be injected at this dosage) to obtain after 24 hours of contact time a minimum chlorine residual of 10 mg/litre. The usual dosage used is 50 mg/litre of Javel water.
• Shock chlorine method on dry surfaces: Apply by sparing or sprinkling a concentrated chlorine solution (200 mg/litre) on all surfaces and equipments of the structure. A minimum contact time of 30 minutes is required.
After this disinfection the structure can be filled with water.
Check that all drain valves, sampling valves are closed.
Check that all structures and reagent dosage areas are clean.
Check that all required gate valves and penstocks are open on the used circuits.
Check that all manual isolating valves on suction and delivery circuit used are open.
Check that electrical power is available.
Check that all the mechanical, electrical, electro – mechanical equipment and instrumentations are available and in working order.
Check and ensure that all the equipment has been lubricated according to the manufacturer’s instructions notices.
Ensure that all chemicals are available and check the chemical dosage settings.
Check the correct operation of all chemical circuits as well as absence of leakages, from the storage tanks to the injection points.
Inform the installation manager of any anomaly and carry out all necessary maintenance before start-up.
Ensure that all safety and security instructions are adhered to. These include local site and National rules and regulations and instructions.
Refer to manufacturer’s documentation for all specific unit start-up instructions.
Check availability of the raw water to the plant (raw water supply pumps)
Fill the different units with raw water and start all the chemical injections.
Start-up the sedimentation tank
Start-up the Rapid Gravity Filters
Do all the above steps again. Ensure that all is OK.
Carry out all the necessary analyses.
Adjust the filters out flow by setting the level in the level transmitter housing
Wash the filters
After washing the filters, start-up the disinfection chlorine and final adjustment.
9.1.2 Clarifier Start-up
Start-up preliminaries
Make sure that the cleaning has been correctly performed, particularly as regards the bottom of the sludge hoppers, the bottom of the clarifier, the general distribution channel, in order to avoid clogging of branches, distribution orifices, and sludge draw off pipes.
Check proper operation of the auto desludge actuated butterfly valve.
Check the time for the control of the auto desludge valve.
Check proper operation of all the manual valves, in particular drain valves.
Filling with water: Supply the clarifier with raw water from aerator.
9.1.3 Rapid Gravity Filters
Preliminary checks include,
Cleaning bottom of filter and filter and water channel.
Check if the blower actuated ball valve is operating.
Filter floor protection during back wash.
Horizontality of weirs
Make sure the weirs of the wash water collection trough are horizontal using a level
9.2 PLANT SHUT DOWN
Shut-down procedure involves the systematic stopping of the treatment process. The different modes of shut-down include: normal shut-down of the plant, partial shut-down of the plant, placing the plant on standby and emergency shut-down of the plant (Sinnott, 2005). These different modes of shut-down are normally activated by alarms and safety trip systems as well as interlock systems.
9.2.1 For A Shut Down Less Than One Week
Shut down each unit.
Shut down all chemical units and rinse all lines (see chemical units).
Restart normally.
9.2.2 For A Shut Down Between One and Two Weeks
Same as 9.2.1
Empty filters.
Before shut down, use an excessive amount of chlorine to prevent bacterial growth in the structures (if the chlorination is not available, pour chlorine dosed at the breakpoint + 5 ppm for one hour).
Restart normally. Wash filters according to first time washing procedures given in Section
9.2.3 For A Shut Down Between Two Weeks And One Month
Same as 9.2.2
Empty and clean the tanks of certain chemicals (lime, Calcium hypochlorite, etc.); fill these tanks with service water.
Restart normally after preparing the chemicals.
9.2.4 For A Shut Down Over One Month
Same as 9.2.3
Empty all chemical tanks, clean them and fill them with service water.
Clean all plant components.
Empty and clean all the structures.
Restart as for initial start-up.
9.1 START UP PROCEDURES
9.1.1 General Start-Up Procedures
The following points are checked at each start-up, after the initial commissioning start- up carried out by
Carry out an initial disinfection of all structures (shock chlorination) as follows:
According to American American Water Works Association (AWWA) standards one of the following two methods can be used for initial disinfections:
• Residual method: Fill the structure with water to sufficient chlorine (Javel water or chlorine if this can be injected at this dosage) to obtain after 24 hours of contact time a minimum chlorine residual of 10 mg/litre. The usual dosage used is 50 mg/litre of Javel water.
• Shock chlorine method on dry surfaces: Apply by sparing or sprinkling a concentrated chlorine solution (200 mg/litre) on all surfaces and equipments of the structure. A minimum contact time of 30 minutes is required.
After this disinfection the structure can be filled with water.
Check that all drain valves, sampling valves are closed.
Check that all structures and reagent dosage areas are clean.
Check that all required gate valves and penstocks are open on the used circuits.
Check that all manual isolating valves on suction and delivery circuit used are open.
Check that electrical power is available.
Check that all the mechanical, electrical, electro – mechanical equipment and instrumentations are available and in working order.
Check and ensure that all the equipment has been lubricated according to the manufacturer’s instructions notices.
Ensure that all chemicals are available and check the chemical dosage settings.
Check the correct operation of all chemical circuits as well as absence of leakages, from the storage tanks to the injection points.
Inform the installation manager of any anomaly and carry out all necessary maintenance before start-up.
Ensure that all safety and security instructions are adhered to. These include local site and National rules and regulations and instructions.
Refer to manufacturer’s documentation for all specific unit start-up instructions.
Check availability of the raw water to the plant (raw water supply pumps)
Fill the different units with raw water and start all the chemical injections.
Start-up the sedimentation tank
Start-up the Rapid Gravity Filters
Do all the above steps again. Ensure that all is OK.
Carry out all the necessary analyses.
Adjust the filters out flow by setting the level in the level transmitter housing
Wash the filters
After washing the filters, start-up the disinfection chlorine and final adjustment.
9.1.2 Clarifier Start-up
Start-up preliminaries
Make sure that the cleaning has been correctly performed, particularly as regards the bottom of the sludge hoppers, the bottom of the clarifier, the general distribution channel, in order to avoid clogging of branches, distribution orifices, and sludge draw off pipes.
Check proper operation of the auto desludge actuated butterfly valve.
Check the time for the control of the auto desludge valve.
Check proper operation of all the manual valves, in particular drain valves.
Filling with water: Supply the clarifier with raw water from aerator.
9.1.3 Rapid Gravity Filters
Preliminary checks include,
Cleaning bottom of filter and filter and water channel.
Check if the blower actuated ball valve is operating.
Filter floor protection during back wash.
Horizontality of weirs
Make sure the weirs of the wash water collection trough are horizontal using a level
9.2 PLANT SHUT DOWN
Shut-down procedure involves the systematic stopping of the treatment process. The different modes of shut-down include: normal shut-down of the plant, partial shut-down of the plant, placing the plant on standby and emergency shut-down of the plant (Sinnott, 2005). These different modes of shut-down are normally activated by alarms and safety trip systems as well as interlock systems.
9.2.1 For A Shut Down Less Than One Week
Shut down each unit.
Shut down all chemical units and rinse all lines (see chemical units).
Restart normally.
9.2.2 For A Shut Down Between One and Two Weeks
Same as 9.2.1
Empty filters.
Before shut down, use an excessive amount of chlorine to prevent bacterial growth in the structures (if the chlorination is not available, pour chlorine dosed at the breakpoint + 5 ppm for one hour).
Restart normally. Wash filters according to first time washing procedures given in Section
9.2.3 For A Shut Down Between Two Weeks And One Month
Same as 9.2.2
Empty and clean the tanks of certain chemicals (lime, Calcium hypochlorite, etc.); fill these tanks with service water.
Restart normally after preparing the chemicals.
9.2.4 For A Shut Down Over One Month
Same as 9.2.3
Empty all chemical tanks, clean them and fill them with service water.
Clean all plant components.
Empty and clean all the structures.
Restart as for initial start-up.
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