When HF- and NH₃-containing exhaust streams are combined in one wet scrubber, acid-base reactions can create ammonium-fluoride-containing dissolved solids or deposits depending on local chemistry. Blowdown, evaporation, mixing, distributor opening size, packing geometry, material compatibility, solids removal, and whether the exhaust streams should be staged separately should be reviewed together.

When a packed TEG contactor begins foaming or losing glycol after hydrocarbon contamination enters the system, investigate upstream separation, glycol condition, surface wetting, gas velocity, liquid circulation, differential pressure, and mist-eliminator loading before replacing packing. The tower may be hydraulically reacting to contaminated absorbent rather than defective internals.

When a CO₂ amine absorber develops unstable pressure drop and carryover despite mechanically clean structured packing, investigate hydrocarbon contamination, degradation products, heat-stable salts, solids, solvent filtration, anti-foam use, distributor stability, and demister loading. Packing replacement alone may not solve a solvent-condition problem.

For H₂S biotrickling filters, packing selection should balance biological surface area with open void space, biomass growth, irrigation, pressure-drop increase, sulfur-product accumulation, cleaning, and support-grid drainage. Strong initial removal does not guarantee long-term performance if biofilm progressively blocks the media.

When an exhaust contains both SO₂ gas and fine sulfuric-acid mist, evaluate gas absorption and aerosol separation separately. A packed bed may remove SO₂ effectively while very fine acid droplets require dedicated high-efficiency mist elimination. Droplet-size distribution, condensation location, gas velocity, material compatibility, pressure-drop allowance, and separate gas/aerosol acceptance criteria should be defined.