High-rate nitrification of saline wastewaters using fixed-bed reactors.

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Microbial Ecology

Background:

• Fixed-bed reactors (FBRs) are effective for high-rate nitrification.
• Limited research exists on salinity's impact on these systems.
• Nitrification is crucial for removing ammonia from wastewater.

Purpose of the Study:

• To investigate the effect of increasing chloride concentrations on nitrifying FBR performance.
• To compare FBRs using different media and feed water types under saline conditions.
• To assess the robustness of high-rate nitrification under elevated salinity.

Main Methods:

• Operated two lab-scale FBRs with stable biofilms for 100 days.
• Gradually increased chloride concentration from 4 to 16 g/L.
• Utilized plastic carriers and clay beads with varying up-flow velocities and feed water (landfill leachate concentrate and synthetic wastewater).

Main Results:

• Plastic carrier FBR achieved >97% ammonia removal; clay bead FBR achieved ~70% removal.
• Organic compounds in leachate temporarily inhibited nitrifiers, causing nitrite accumulation.
• Increased chloride content did not adversely affect reactor performance.
• Clay bead FBR primarily converted ammonia to nitrate.

Conclusions:

• High-rate nitrifying FBRs demonstrate resilience to increased salinity.
• Reactor performance is influenced by media type, porosity, and feed water composition.
• Nitrification processes in FBRs can be robust under varying environmental conditions.