Risk of hydrogen sulfide pollution from pressure release resulting from landfill mining

Area of Science:

• Environmental Science
• Geochemistry
• Microbiology

Background:

• Landfill mining (LFM) offers resource recovery and land reuse benefits.
• Assessing environmental risks, particularly gas emissions, is crucial for LFM sustainability.
• Pressure changes during LFM can potentially trigger hazardous gas releases.

Purpose of the Study:

• To investigate the risk of hydrogen sulfide (H2S) pollution from pressure release simulated during landfill mining.
• To evaluate the impact of different initial pressures and temperatures on H2S generation and release.
• To analyze the microbial community shifts, specifically sulfate-reducing bacteria (SRB), in response to pressure release.

Main Methods:

• Simulated LFM-induced pressure release in small-scale anaerobic batch reactors.
• Tested initial pressures ranging from 0.2 to 0.6 MPa at 25°C and 50°C.
• Measured H2S concentrations and performed microbial diversity analysis (16S rRNA gene sequencing).

Main Results:

• H2S concentration significantly increased post-pressure release, peaking at 19366 mg·m⁻³ (25°C) and 24794 mg·m⁻³ (50°C) at 0.6 MPa.
• H2S release duration was notably longer (>90 days) at 25°C compared to 50°C.
• Microbial analysis revealed temperature-dependent SRB community responses, with phylogenetic similarity at low temperatures and enrichment of specific genera (e.g., Desulfovibrio, Candidatus Desulforudis) at high temperatures.

Conclusions:

• Landfill mining-induced pressure release poses a significant risk of H2S pollution.
• Temperature influences both the extent and duration of H2S release and the adaptive mechanisms of SRB communities.
• Effective environmental management strategies are necessary to mitigate secondary risks associated with LFM operations.