What causes a dissolved air flotation plant to fail

DAF Plant Failure Causes

A dissolved air flotation (DAF) plant can fail due to several interrelated factors that disrupt its core functions of air bubble generation, contaminant attachment, and solids separation.

Inadequate Maintenance

• Over time, the air dissolving system—including pumps, diffusers, and pressure vessels—can accumulate scale, sludge, or debris.
• This buildup clogs pathways for air or water, reducing the production of tiny, uniform bubbles critical for effective flotation.
• Without properly sized bubbles, contaminants cannot attach and rise to the surface, leading to poor treatment performance or complete system failure.

Chemical Imbalance

• If coagulants or flocculants are dosed incorrectly—either too little or too much—it disrupts the formation of stable flocs that bind to contaminants.
• Insufficient chemical dosing leaves contaminants dispersed, while excessive dosing creates oversized flocs that either sink or block the flotation zone.
• Changes in wastewater composition—such as sudden spikes in oil concentration, pH levels, or temperature—can render pre-set chemical doses ineffective.

Mechanical Damage

• The skimming mechanism, which removes floating contaminants, can wear out or become misaligned with prolonged use.
• A faulty skimmer leaves floating sludge or oil in the tank, causing recontamination of treated water.
• Damaged valves or seals in the air or water lines can lead to pressure leaks, preventing the air dissolving system from reaching the required pressure to generate bubbles.

Environmental Stressors

• Exposure to extreme temperatures can damage polymer components in the DAF plant, such as gaskets or membrane diffusers.
• In cold conditions, water can freeze in pipes or tanks, expanding and cracking the system.
• Corrosive substances in certain industrial wastewaters can erode metal parts like tanks or pumps, weakening their structure and compromising the plant's integrity over time.

All these factors, when left unaddressed, can cause a DAF plant to fail in meeting its treatment goals.