When a high-pH ammonia stripper treating landfill leachate develops scale, evaluate calcium, magnesium, alkalinity, carbonate chemistry, CO₂ stripping, pH setpoint, packing openness, distributor fouling, and pretreatment. Better NH₃ speciation can create a new precipitation problem inside the tower.

When a permanganate odor scrubber develops manganese-containing deposits, evaluate reaction chemistry, pH, oxidant concentration, solids generation, distributor opening size, packing openness, sump solids removal, and cleaning. The tower may be fouling because successful oxidation creates insoluble reaction products.

When TEG dehydration performance declines and the regenerator shows deposits or unstable operation, investigate salts, hydrocarbons, corrosion products, glycol degradation, filtration, reboiler conditions, and regenerator packing before changing the gas-contactor internals.

When amine-system performance declines because heat-stable salts accumulate, more regenerator packing or higher reboiler duty may not solve the problem. Analyze solvent composition, degradation, corrosion, fouling, reclaiming needs, and actual regenerator hydraulics separately before changing tower internals.

When an HCl pickling scrubber loses removal efficiency while pressure drop remains normal, inspect for oil-mist contamination and hydrophobic films. Oil can reduce aqueous wetting, spread through the recirculation loop, and lower effective packing area without causing severe blockage.