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Disentangling microbial coupled fillers mechanisms for the permeable layer optimization process in multi-soil-layering systems

  • 0School of Water Resources and Environment, MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China.
Journal of Environmental Sciences (china) +

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July 13, 2024

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July 13, 2024

View abstract on PubMed

Summary

This summary is machine-generated.

Multi-soil-layering (MSL) systems effectively treat rural wastewater using permeable layers. Zeolite substrates with activated sludge enhance nitrogen removal via heterotrophic nitrification-aerobic denitrification (HN-AD).

Area Of Science

  • Environmental Science
  • Water Treatment Engineering
  • Microbiology

Background

  • Decentralized rural domestic wastewater treatment relies on Multi-Soil-Layering (MSL) systems.
  • Suboptimal nitrogen removal in MSL systems necessitates understanding the role of permeable layers.
  • Investigating diverse substrates and microbial communities is crucial for optimizing MSL performance.

Purpose Of The Study

  • To investigate the mechanisms of rural domestic wastewater purification using different substrates and microbial systems within MSL.
  • To elucidate the role of the permeable layer in enhancing nitrogen removal.
  • To understand the microbial community structure and key metabolic pathways involved in wastewater treatment.

Main Methods

  • Experimental investigation of MSL systems with varied substrates (zeolite, green zeolite, biological ceramsite) and microbial inocula (activated bacterial powder, activated sludge).
  • Performance evaluation based on removal efficiencies of Chemical Oxygen Demand (COD), Total Phosphorus (TP), and Ammonium Nitrogen (NH<sub>4</sub><sup>+</sup>-N).
  • High-throughput 16S rRNA gene sequencing for microbial community analysis.

Main Results

  • Zeolite coupled with microorganisms achieved high removal efficiencies: 93.8% COD, 97.1% TP, and 98.8% NH<sub>4</sub><sup>+</sup>-N within 3 days.
  • Activated sludge demonstrated superior nitrification and overall performance compared to specialized nitrifying bacteria powder.
  • Zeolite exhibited significant NH<sub>4</sub><sup>+</sup>-N desorption (89.4%), with exchanged ammonium being a major component.
  • Microbial analysis revealed dominance of aerobic and parthenogenetic anaerobic bacteria, with absence of obligate anaerobic bacteria.
  • The heterotrophic nitrification-aerobic denitrification (HN-AD) process and denitrifying phosphorus-accumulating organisms (DPAOs) were key for simultaneous N and P removal.

Conclusions

  • The permeable layer is critical for MSL system performance, particularly for nitrogen removal.
  • Zeolite and activated sludge are effective components for enhancing wastewater purification in MSL systems.
  • Understanding the HN-AD mechanism and microbial ecology provides insights for optimizing MSL design and operation for rural wastewater treatment.

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