Performance of autotrophic nitrogen removal from digested piggery wastewater

Area of Science:

• Environmental microbiology
• Wastewater treatment engineering
• Biotechnology

Background:

• Digested piggery wastewater (DPW) presents challenges for effective nitrogen removal.
• Optimizing autotrophic nitrogen removal processes is crucial for sustainable agriculture and environmental protection.

Purpose of the Study:

• To investigate the performance of an autotrophic nitrogen removal process for treating DPW.
• To evaluate the impact of shortened hydraulic retention time (HRT) and increased DPW concentration on nitrogen removal efficiency.
• To analyze the microbial community structure and its correlation with process performance.

Main Methods:

• Gradual shortening of HRT and enhancement of DPW concentration over 390 days.
• Monitoring of total nitrogen removal rate and efficiency.
• High-throughput pyrosequencing for microbial community analysis.
• Measurement of aerobic ammonium oxidizing activity and sludge settling ability (SVI).

Main Results:

• Achieved a total nitrogen removal rate of 3.9 kg-N m^-3 day^-1 and 73% efficiency.
• High relative abundance of Nitrosomonas (4.2%) and functional microbes (12.15%) supported high aerobic ammonium oxidizing activity (1.25±0.1 g-N gVSS^-1 d^-1).
• Good sludge settling ability (SVI, 78.42 mL g^-1 SS) facilitated high sludge concentration (VSS, 11.01 g L^-1).
• DPW, compared to synthetic wastewater, reduced nitrogen-removing microbes but increased anaerobes (15.7%), sulfur-oxidizing bacteria (9.4%), and methanogens (40.8%).

Conclusions:

• The optimized autotrophic nitrogen removal process demonstrates excellent performance in treating DPW.
• Microbial community shifts, including increased anaerobes and methanogens, are characteristic of DPW treatment.
• The study provides a foundation for advanced wastewater treatment strategies using microbial consortia.