Verify that the sludge changed
Check feed solids, pH, conductivity, temperature, volatile fraction, storage and upstream coagulant or cleaning events. Compare the drift with dated plant records.
A constant pump setting is not a constant dry-solids dose when the feed changes.
Recalculate active dose
Confirm sludge flow, solids measurement, neat product feed and active content. Inspect unit conversions and pump calibration.
Correct the measured basis before raising or lowering the dose. Otherwise the response may be misdiagnosed.
Inspect make-down
Look for poor wetting, fisheyes, short aging, excessive concentration, old solution, low water flow or contamination. Check tank turnover and mixer operation.
Prepare a fresh small reference solution. If performance returns, repair preparation before changing product.
Trace the delivery path
Measure metering-pump output at backpressure and inspect valves, quills and tubing. Identify high-shear pumps or mixers after injection.
A partial blockage or air leak can create sudden underfeed even when the display value is unchanged.
Inspect the dewatering machine
Check belt wash, screen fouling, bowl or scroll settings, torque, feed distribution and mechanical wear as applicable. Compare current settings with the approved baseline.
Chemistry cannot compensate reliably for a separator outside its stable operating range.
Use reference comparisons
Test the current product, a retained approved lot and freshly prepared solutions on the same current sludge. Change one factor at a time.
This separates sludge, preparation, machine and supply hypotheses without guessing.
Escalate with a complete record
Send the supplier sample code, lot, process timeline, preparation data, active-dose calculation and measured outcomes. Preserve a current sludge sample when practical.
A structured record enables a targeted response and avoids an uncontrolled sequence of product and machine changes.
Use a fault timeline
Place feed changes, deliveries, make-down alarms, maintenance, laboratory results and separator settings on one timeline. Mark the first verified performance deviation rather than the time the problem was reported.
The sequence often distinguishes a gradual sludge shift from a sudden hardware or preparation failure. Preserve original readings so later conclusions are not based only on operator recollection.
Close the investigation with verification
After correcting the suspected cause, return to a documented reference condition and repeat the key measurements. Confirm the response across more than one sample or operating interval when the fault was intermittent.
Record the correction, evidence and any new monitoring trigger. Do not leave a higher polymer setting as the permanent solution unless active-dose and total-process results support it.
Escalate supply concerns with comparison evidence
If process, preparation and machine checks do not explain the change, compare the current lot with a retained approved reference using fresh solutions and the same current sludge. Record appearance, dissolution, calibrated dose and separator response without assuming the cause in advance.
Send the supplier the product and lot codes, delivery and storage history, COA, preparation record, feed data and paired results. Quarantine or change material only under the plant's quality procedure. A disciplined comparison protects the process while avoiding an unsupported claim that either the sludge or the supplied polymer must be responsible. Retain both solutions and test records until the investigation is closed.