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Partial nitrification performance and microbial community evolution in the membrane bioreactor for saline stream
Yao Yuan1, Zhen Zhou2, Jie Jiang1
1Shanghai Engineering Research Center of Energy - Saving in Heat Exchange Systems, College of Environmental and Chemical Engineering, Shanghai University of Electric Power, Shanghai 200090, China.
Bioresource Technology
|November 26, 2020
Summary
Salinity impacts partial nitrification, enhancing ammonia removal and sludge properties in membrane bioreactors. Salt gradients influence microbial communities and nitrification pathways, promoting salt-tolerant bacteria.
Area of Science:
- Environmental Science
- Microbiology
- Water Treatment Engineering
Background:
- Partial nitrification is crucial for wastewater treatment.
- Salinity is a common challenge in industrial wastewater.
- Understanding salinity effects on partial nitrification is vital for process optimization.
Purpose of the Study:
- To investigate the effects of salinity level and gradient on partial nitrification.
- To analyze sludge properties and microbial activities under varying salinity conditions.
- To optimize partial nitrification membrane bioreactors (PN-MBRs) for saline environments.
Main Methods:
- Utilized partial nitrification membrane bioreactors (PN-MBRs).
- Varied sodium chloride (NaCl) concentrations to simulate different salinity levels.
- Analyzed nitrite accumulation, ammonia removal, oxygen uptake rate, sludge properties, and microbial communities.
Main Results:
- Stable nitrite accumulation (91.1%) and ammonia removal (64.8%) achieved at 10 g/L NaCl.
- Higher salinity (10 g/L NaCl) increased oxygen uptake rate and promoted AOB/NOB differentiation.
- Salinity increased sludge floc size and extracellular polymeric substances (EPS) content, with minimal impact on settleability.
Conclusions:
- Salinity level and gradient are critical for microbial community adaptation to salt-tolerant bacteria.
- PN-MBRs enriched specific aerobic and anaerobic ammonia-oxidizing bacteria (AOBs).
- Salt gradients induce distinct nitrification metabolic pathways, with increasing salinity favoring hydroxylamine oxidizers.
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