Enhanced nitrogen removal from electroplating tail wastewater through two-staged anoxic-oxic (A/O) process

Area of Science:

• Environmental Science
• Microbiology
• Chemical Engineering

Background:

• Electroplating wastewater poses environmental challenges due to high electrical conductivity and ammonia nitrogen.
• Existing treatment methods may struggle with the complex composition of electroplating tail wastewater.

Purpose of the Study:

• To evaluate the effectiveness of a two-staged A/O process for treating electroplating tail wastewater.
• To assess the microbial community adaptation to high salinity and ammonia nitrogen.

Main Methods:

• Application of a two-staged A/O process with anaerobic (ANA), anoxic-1 (AN1), aerobic-1 (AE1), anoxic-2 (AN2), and aerobic-2 (AE2) reactors.
• Salinity shock tests using NaCl concentrations from 1 to 10 g/L.
• High-throughput sequencing for microbial community analysis.

Main Results:

• Achieved high removal efficiencies for ammonia nitrogen (NH4+-N) at 97.11% and Chemical Oxygen Demand (COD) at 83.00%.
• Aerobic reactors (AE1 and AE2) demonstrated enhanced resistance to short-term salinity shocks.
• High-throughput sequencing revealed enrichment of nitrogen-removing bacteria (Nitrosomonas, Nitrospira, Thauera) and the presence of salt-tolerant and halophilic bacteria.

Conclusions:

• The two-staged A/O process is highly effective for treating electroplating wastewater.
• The microbial community within the system acclimated to high electrical conductivity and adapted to the wastewater characteristics.
• This process offers a viable solution for managing challenging industrial effluents.