Study on zeolite enhanced contact-adsorption regeneration-stabilization process for nitrogen removal

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Microbial Ecology

Background:

• Conventional contact stabilization activated sludge (CS) processes face limitations in efficient ammonium removal.
• Zeolite's preferential ion exchange capacity offers potential for upgrading existing wastewater treatment systems.

Purpose of the Study:

• To introduce and evaluate a novel nitrogen removal process, the zeolite enhanced contact-adsorption regeneration-stabilization (ZCS) process.
• To compare the performance of the ZCS process against the conventional CS process for municipal wastewater treatment.

Main Methods:

• Implementation of the ZCS process utilizing zeolite for ammonium adsorption and biological regeneration.
• Performance evaluation through monitoring effluent ammonium concentration, microbial diversity (PCR-DGGE), and pilot-scale testing.
• Optimization using orthogonal experiments to determine key operational parameters.

Main Results:

• The ZCS process achieved an effluent ammonium concentration of approximately 6.83 mg/L, enhancing removal efficiency by over 27% compared to the CS process.
• PCR-DGGE analysis indicated higher microbial diversity, uniformity, and abundance in the ZCS process.
• An anoxic/oxic (A/O) regeneration process with a 2:1 oxic to anoxic tank ratio was found to be optimal.
• Pilot-scale tests confirmed effective biological regeneration of ammonium-saturated zeolite.
• Zeolite powder dose and external recycle ratio were identified as significant factors influencing nitrogen and ammonium removal.

Conclusions:

• The ZCS process represents a significant upgrade to conventional activated sludge systems for enhanced nitrogen and ammonium removal.
• The biological regeneration of zeolite is effective and feasible for continuous operation.
• Optimizing zeolite dosage and recycle ratios is crucial for maximizing the efficiency of the ZCS process.