High-rate dissolved air flotation for water treatment

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Flotation Processes

Background:

• Raw water treatment often faces challenges with color, turbidity, and suspended solids.
• Dissolved Air Flotation (DAF) is a key technology for water purification.
• Optimizing DAF unit design and operational parameters is crucial for efficient water treatment.

Purpose of the Study:

• To experimentally investigate the performance of a pilot-scale horizontal flow high-rate Dissolved Air Flotation (HRDAF) unit.
• To evaluate the impact of water velocity, supplied air value, and plate angle on flotation efficiency.
• To determine optimal operating conditions for treating colored, low-turbidity raw water.

Main Methods:

• Conducted experiments using a pilot-scale HRDAF unit with inclined parallel plates.
• Varied water velocity (Vh) from 18 to 96.5 cm/min and supplied air (S*) from 2.2 to 8.5 g/m³.
• Tested plate angles of 60 and 70 degrees, using aluminum sulfate as a coagulant.

Main Results:

• Optimal conditions: S* of 4.0 g/m³ and Vh of 18 cm/min achieved high removal efficiencies.
• Achieved removal rates: 90% color, 88% turbidity, and 94% total suspended solids (TSS).
• The unit demonstrated good performance even at higher Vh up to 76 cm/min, indicating high-rate capability.

Conclusions:

• The HRDAF unit with inclined plates is highly effective for treating colored and low-turbidity raw water.
• Low air requirements and high treatment rates characterize the optimized operational conditions.
• The study confirms the potential of this DAF configuration for efficient and cost-effective water purification.