AirPrex - Patented Sludge Optimization System

This environmentally friendly and cost-saving process also has disadvantages:

• In the anaerobic environment, the struvite deposits in piping, pumps and equipment, thereby reducing the performance of the treatment plant.
• The high phosphate concentration in the anaerobic sludge leads to inefficient sludge dewatering.
• The separated sludge liquor has a high phosphate back load.

This is how AirPrex works:

The AirPrex process improves biological phosphate elimination. The digested sludge is fed into the AirPrex reactor where it is subjected to CO2 stripping through aeration. The CO2 increases the pH of the sludge significantly. At the same time, the addition of magnesium salts leads to the formation and precipitation of magnesium-ammonium-phosphate (MAP). The crystals integrate homogeneously into the sludge matrix. The recovered MAP can then be used as fertilizer.

AirPrex can significantly increase the profitability of a sewage treatment plant. The unique solution for the struvite problem ensures smooth processes and best results in phosphate elimination:

• Improved sludge dewatering
• Lower polymer consumption
• Lower Ortho-P chargeback to biological treatment
• Reduced struvite deposits

AirPrex Micro Process

With AirPrex Micro there is no struvite recovery, microcrystals remain in sludge for targeting ≥ 80% P recovery from ash.

Benefits:

• Increase of cake dryness by up to 4%
• Less polymer consumption (15-25%)
• Reduction of ortho-P by 95 % in the filtrate (internal recycling)
• Prevention of crystallization in the sludge- and centrate area

AirPrex Macro Process

AirPrex Macro, besides struvite harvesting, includes further P release into the second mixing tank where further struvite growth and sedimentation occurs, enabling microcrystals recovery.

Benefits:

The same benefits as AirPrex^® Micro and additionally:

• Increase of cake dryness by up to 4%
• Less polymer consumption (15-25%)
• Reduction of ortho-P by 95 % in the filtrate (internal recycling)
• Prevention of crystallization in the sludge- and centrate area