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A procedure to Drain and Rinse the DAF
Once in every week. [Operate Auger/Auger Drain Valve once in every shift]
This operation normally takes over an hour and less than 2, but no breaks - continue to work till finished.
Inspect all 24 whitewater injection valves, noting which needs unplugging. Clean skimmer flights and get as much of the solids into the discharge tanks as possible.
FEB tank needs to be at a low level: 4 to 5 feet.
Turn off FEB pump.
Open Influent valve from FEB to 100% to drain as much water from pipe as possible.
Close Influent valve from FEB.
Turn off polymer pumps. Close polymer piping valves.
Decant BOTH DAF SPN Discharge tanks and pump BOTH empty.
Open Influent valve from EQ tanks. [Under catwalk under DAF control panel]
Close Discharge Valve of EQ Feed pump #2 [East] to FEB.
Open Discharge Valve of EQ Feed pump #2 to DAF, then open Valve on top of East EQ tank.
Turn on EQ Feed pump #2 ['Manual' switch position]. [A high level in EQ tanks will turn on EQ Feed pump #1 which will pump from EQ tanks to FEB tank]. [A jumper on terminal strip in DAF control panel is an alternate method].
Level in DAF should start dropping.
Turn off 'white water' Recirculation pump. Close all whitewater injection valves [to prevent plugging].
Position Skimmers one flight past the ramp and turn off. [To make it easier to rinse from end to end].
About 40 minutes later, the level should be as low as it will get using the Bernoulli Effect. Daniel Bernoulli, 1700-1782, has often been called the first mathematical physicist. His greatest work was his Hydrodynamica (1738), which included the principle now known as Bernoulli's principle and anticipated the law of conservation of energy and the kinetic-molecular theory of gases developed a century later. He also made important contributions to probability theory, astronomy, and the theory of differential equations. The pressure is lower in a moving fluid than in a stationary fluid. This effect is called the Bernoulli effect. If you put the convex side of a spoon into a smooth stream of water from the faucet, you will feel the spoon pulled into the stream. The higher pressure outside the moving fluid pushes the spoon into the lower pressure water.
Open Auger drain valve. Air operated. [to close: switch tubing airline then close valve then put airline back.]
Turn on Auger. Plugging is possible. Reverse rotation usually clears obstruction (May take 20 minutes).
East DAF/SPN Discharge tank should hold the remaining water/SPN without overflowing.
Turn off EQ Feed pump #2.
Close Influent valve from EQ tanks. [Under catwalk under DAF control panel].
Open Discharge Valve of EQ Feed pump #2 [East] to FEB.
Close Discharge Valve of EQ Feed pump #2 to DAF, then
Close Valve on top of East EQ tank.
Open 8" valve to drain on side of tank, 3 or 4 turns decanting water to meat side sump.
Open decant valve also [purge/clear as necessary].
Rinse DAF.
Close decanting valves.
Pump solids/fines/spn to SPN pit.
Returning to Normal service is NOT nearly in reverse order.
Stop pumping from DAF Discharge tank to SPN pit.
Now is the time to unplug all whitewater injection valves.
Open Influent valve from FEB wide open.
Leave FEB pump off, fill by gravity to start with.
Close Auger Drain Valve. Begin filling DAF from FEB. May need to cycle Auger Drain Valve once more to clear settled fines. Open decant valve [purge/clear as necessary].
Continue filling DAF from FEB until several inches cover the bottom at the effluent end of the DAF. Open all whitewater injection valves full open, then turn on Recirculation Pump to start the 'whitewater'. Check Pressure, adjust all whitewater injection valves to see whitewater in tubing, check pressure again. Turn on both polymer pumps in manual mode 30% ,
Turn Effluent Valve control to "Auto" 'PLT'. The first overflow of the effluent weir will have lots of
carryover of solids. This will return the DAF effluent back to the EQ tank [via the meat side sump] [the two valves
at the effluent end of the DAF will switch, air operated].
Start Skimmers, speed up. When level rises to contact skimmers, slow flow to 90 GPM. Use hose at weir to agitate
and break loose any trapped caked solids. When clear water passes over weir, switch Effluent Valve control to "Manual".
Now, the processed water will flow to the lagoon system.
Task is Completed.
Resume 'Normal' process.