Nitrate removal from drinking water using a membrane-fixed biofilm reactor

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Microbiology

Background:

• Conventional physico/chemical water treatment methods are often costly.
• Biological denitrification faces challenges with post-treatment to remove microorganisms and carbon sources.
• A new approach is needed to enhance the efficiency and reduce the complexity of biological water treatment.

Purpose of the Study:

• To develop and test a novel membrane-based bioreactor for biological denitrification.
• To overcome the limitations of intensive post-treatment in conventional biological denitrification.
• To evaluate the effectiveness of separating the reaction zone and carbon supply from the raw water stream.

Main Methods:

• Utilized a nitrate-permeable membrane to immobilize a denitrifying biofilm.
• Investigated different membrane types and reactor configurations in bench-scale runs.
• Assessed denitrification rates and the barrier properties of the membrane against carbon source and nutrient diffusion.

Main Results:

• Achieved high denitrification rates of up to 1230 mg NO3(-)-N m-2 day-1.
• Demonstrated complete nitrate removal from raw water containing 100 mg NO3- l-1 in one experiment.
• Observed no significant diffusion of ethanol or phosphate from the bioreactor into the treated water.
• Effluent quality met most drinking water criteria, with only a slight increase in colony count.

Conclusions:

• The membrane-based bioreactor effectively removes nitrates from drinking water.
• Separating the biological reaction zone and carbon supply via a membrane simplifies post-treatment.
• This technology offers a cost-effective and efficient alternative for biological water treatment.