Operational strategy for solid phase denitrification to achieve carbon balance between organic release and...

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Microbial Ecology

Background:

• Nitrate contamination in water bodies poses significant environmental and health risks.
• Solid-phase denitrification offers a promising approach for nitrate removal, but balancing carbon sources and microbial activity is crucial.
• Developing efficient and stable reactor designs is essential for effective wastewater treatment.

Purpose of the Study:

• To develop and evaluate a pilot-scale vertical-baffled solid-phase denitrification reactor (VbSPDR).
• To investigate the impact of polycaprolactone (PCL) and ceramsite fillers on nitrate removal and organic carbon release.
• To optimize operational parameters for maximum nitrate removal and minimal effluent chemical oxygen demand (COD).

Main Methods:

• Utilized a pilot-scale VbSPDR with PCL and ceramsite as composite fillers.
• Employed Box-Behnken design to study the effects of hydraulic retention time (HRT), temperature, and influent nitrate concentration.
• Analyzed microbial communities and their metabolic functions within the reactor.

Main Results:

• Achieved a 95% nitrate removal rate under optimal conditions (33°C, 1.22 h HRT, 19 mg/L influent nitrate).
• Minimized effluent COD to 2.5 mg/L at 13°C, 0.39 h HRT, and 19 mg/L influent nitrate.
• Identified specific bacterial genera (Comamonadaceae, Acidovorax, Phreatobacter) enriched by PCL and ceramsite, facilitating hydrolysis-acidification and COD metabolism.

Conclusions:

• The VbSPDR with PCL and ceramsite fillers effectively enhances nitrate removal and controls effluent COD.
• Inorganic fillers play a vital role in supporting microbial communities for efficient denitrification and carbon management.
• The reactor design and filler combination demonstrate potential for robust wastewater treatment under varying operational conditions.