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Secondary Clarifier & RAS Pumps Procedures

Secondary  Clarifiers  & RAS Pumping
Process Flow Diagrams Process Plan and Section Diagrams
Process Flow Schematic Secondary Clarifier Process Plan View
Secondary Clarifier & RAS Pumping PID Secondary Clarifier Process Section View
  RAS Pump Plan View
  RAS Pump Section View
Secondary Scum Pump Plan & Section View


Secondary Clarifier Process Procedures 
Startup Procedures
Local Manual Mode
1. Open the secondary clarifier effluent manual slide gate at the UV Disinfection Facility (G9061 or G9062).
2. Open the existing secondary clarifier influent gate(s) at the mixed liquid junction box at the aeration basin. If more than one secondary clarifier is in service, adjust the influent gates to maintain an equal flow split between the clarifiers.
3. Once the clarifier rakes have been covered, manually turn ON the Secondary Clarifier Mechanism locally at the clarifier drive.
 
Shutdown Procedures
Local Manual Mode
1. Close the existing manual secondary clarifier influent gate at the mixed liquor junction box.
 
2. Close the secondary clarifier effluent manual sluice gate at UV Disinfection Facility (G9061 of G9062).

3. Turn the secondary clarifier drive OFF, locally at the clarifier drive. It is wise to remove as much RAS as possible from the clarifier blanket prior to taking a clarifier off-line for a period of time.

4. To drain a clarifier, operate the existing clarifier drain valve and WAS pump to remove the sludge blanket to WAS thickening or to the mixed liquid junction box. Be careful not to pump clarified secondary effluent to WAS thickening after the sludge blanket has been pumped out of the offline clarifier.
 
Scum Pumping Process Procedures
Startup Procedures
Remote Manual Control
1. Through the PCS, set the Secondary Clarifier Scum Washdown Valve to AUTO mode. The valve will be automatically opened for a preset length of time every time the secondary clarifier rake arm approaches the secondary clarifier scum beach.

2. Set the Scum Pump discharge valves to direct scum to either WAS thickening or the mixed liquor junction box.

3. On the Blower Building MCC-2, select REMOTE operation for the Secondary Clarifier Scum Pump.

4. The gravity belt thickener must be operating for the scum to be directed to the solids process. Initiate Secondary Clarifier Scum Pump CYCLE START command through either the PCS or locally.
Local Manual Control
1. Set the Scum Pump discharge valves to direct scum to WAS thickening or the mixed liquor junction box.

2. On the Blower Building MCC-2, select ON operation for the Secondary Clarifier Scum Pumps.
 
Shutdown Procedures
Remote Manual Control
1. The Secondary Clarifier Scum Pump will automatically shut down once the Secondary Clarifier Scum Pit level drops below 1.5 feet.
Local Manual Control
1. On the Blower Building MCC-2, select OFF operation for the Secondary Clarifier Scum Pumps.

RAS Pumping Process Procedures 

Startup Procedures

Influent Flow/RAS Flow Ratio Control Mode
1. On the Return Activated Sludge Pump adjustable speed drive panels (ASD3331 and ASD3332), located adjacent to the RAS pumps, select REMOTE operation.
 
2. Through the PCS, set the Return Activated Sludge Pumps to AUTO mode and initiate a START command for pumps selected to operate.

3. Through the PCS, set the Secondary Clarifier RAS Flow controller to RATIO mode.

4. Through the PCS, set the Secondary Clarifier Withdrawal Ratio (adjustable between 0 and 100 Percent), based on the desired percent of WAS flow to be drawn from the clarifier, and set the Influent Flow / RAS Flow Ratio (adjustable between 0 and 100 Percent).

 The total RAS flow rate to the Aeration Basins will be automatically adjusted to maintain the operator-entered ratio with respect to the Plant Influent Flow. In addition, the sludge withdrawal flow ratio between the two Secondary Clarifiers will be adjusted to maintain the operator-entered sludge withdrawal ratio.
 
Remote Auto Control Mode
1. On the Return Activated Sludge Pump adjustable speed drive panels (ASD3331 through ASD3332), located in the blower building, select REMOTE operation.

2. Through the PCS, set the Return Activated Sludge Pumps to AUTO mode.

3. Initiate a START command for pumps selected to operate.

4. Enter a Secondary Clarifier RAS flow withdrawal set point from each Secondary Clarifier (Adjustable between 0 and 3.0 mgd). This will adjust the flow over the RAS weir gates.

Remote Manual Control
1. On the Return Activated Sludge Pump adjustable speed drive panels (ASD3331 through ASD3332), located in the blower building, select REMOTE operation.
 
2. Through the PCS, set the Return Activated Sludge Pumps MANUAL mode.

3. Through the PCS, set the pump speed set point and initiate a pump START command.

Local Manual Control
1. On the Return Activated Sludge Pump adjustable speed drive panels (ASD3331 through ASD3332), located in the blower building, select REMOTE operation.

2. On the drive panel, set the pump speed set point and initiate a pump START command.
 
Shutdown Procedures
Influent Flow / RAS Flow Ratio Control Mode
1. Through the PCS, set the Return Activated Sludge Pumps to MANUAL mode.

2. Through the PCS, initiate a STOP command for pumps selected to shut down.
Remote-Auto Mode
1. Through the PCS, initiate a STOP command for pumps selected to shut down.
Remote Manual Control 
1. Through the PCS, initiate a STOP command for pumps selected to shut down.
Local Manual Control 
1. On the Return Activated Sludge Pump drive panel, located in the Blower Building, initiate a STOP command for pumps selected to shut down.


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Last Updated: 9/16/2013 9:36:35 AM
Version 4.0.1