Simultaneous nitrification-denitrification and phosphorus removal in a fixed bed sequencing batch reactor (FBSBR)

Area of Science:

• Environmental Engineering
• Wastewater Treatment Technologies
• Biological Nutrient Removal (BNR)

Background:

• Conventional activated sludge systems in sequencing batch reactors (SBRs) face challenges in achieving high nutrient removal efficiencies.
• The need for enhanced biological nutrient removal (BNR) processes is critical for effective wastewater treatment.
• Fixed-media reactors offer an alternative to suspended growth systems for improved wastewater treatment performance.

Purpose of the Study:

• To investigate the efficacy of a fixed bed sequencing batch reactor (FBSBR) utilizing polypropylene carriers for biological nutrient removal.
• To compare the performance of FBSBR with a conventional SBR in terms of carbon, nitrogen, and phosphorus removal.
• To assess the impact of fixed media on biomass production yield and sludge characteristics.

Main Methods:

• A fixed bed sequencing batch reactor (FBSBR) with polypropylene carriers was operated and compared against a conventional SBR.
• Performance was evaluated based on chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) removal efficiencies at various loading rates.
• Biomass production yield was monitored by measuring MLSS concentrations relative to COD removal.

Main Results:

• The FBSBR demonstrated significantly higher removal efficiencies for COD (90-96%), TN (60-88%), and TP (76-90%) compared to the SBR (85-95%, 38-60%, 20-79%, respectively).
• Simultaneous nitrification-denitrification (SND) rates were substantially higher in the FBSBR, attributed to oxygen gradients within the biofilm.
• The FBSBR exhibited a lower observed sludge production yield (Y(obs)) and produced less excess sludge with higher nutrient content and stabilization.

Conclusions:

• Fixed bed sequencing batch reactors (FBSBRs) with polypropylene carriers are highly effective for simultaneous nitrification-denitrification and phosphorus removal.
• The FBSBR technology offers superior nutrient removal performance and reduced sludge production compared to conventional SBRs.
• The findings highlight the potential of FBSBRs for advanced and sustainable wastewater treatment solutions.