Sequential sulfur-based denitrification/denitritation and nanofiltration processes for drinking water treatment

Area of Science:

• Environmental Science
• Water Treatment Engineering
• Microbiology

Background:

• Nitrogen contamination in groundwater poses risks to drinking water safety.
• Efficient and cost-effective nitrogen removal methods are crucial for water treatment.
• Autotrophic nitrogen removal offers a promising biological approach.

Purpose of the Study:

• To evaluate a combined groundwater treatment process for nitrogen removal and sulfate reduction.
• To investigate autotrophic nitrogen removal under various conditions in a sulfur-packed bed reactor (SPBR).
• To assess excess sulfate removal using nanofiltration (NF).

Main Methods:

• Sequential treatment: SPBR for nitrogen removal and NF for sulfate rejection.
• SPBR operation under different nitrate/nitrite loading rates and feeding strategies.
• Batch activity tests and Illumina sequencing for microbial analysis.
• Dead-end filtration tests with NF membranes.

Main Results:

• Effective nitrogen removal achieved through the combined SPBR and NF process.
• Autotrophic nitrogen removal efficiency varied with loading rates and feeding strategies.
• High nitrogen loading rates are necessary to prevent excess sulfide generation.
• NF successfully rejected excess sulfate from the SPBR effluent.

Conclusions:

• The combined SPBR-NF system is effective for treating nitrogen-contaminated groundwater.
• Optimizing nitrogen loading rates in the SPBR is critical for process efficiency.
• This approach offers a viable solution for producing safe drinking water from contaminated sources.