Biodiversity in wetland+ system: a passive solution for HCH dump effluents

Area of Science:

• Environmental Science
• Environmental Engineering
• Ecotoxicology

Background:

• Hexachlorocyclohexane (HCH) isomers, banned pesticides, persist globally despite decades of prohibition.
• Contaminated water bodies pose risks to ecosystems and human health.
• Remedial technologies are crucial for mitigating the impact of persistent organic pollutants.

Purpose of the Study:

• To evaluate the efficacy of the Wetland+ system in removing HCH and chlorobenzenes (ClB).
• To investigate the mechanisms of pollutant removal, including biodegradation.
• To assess the impact of Wetland+ operation on the aquatic ecosystem, specifically diatom communities.

Main Methods:

• The Wetland+ system, integrating an aerobic sedimentary tank, permeable reactive barrier (PRB), biosorption, and aerobic wetland, was employed.
• System efficiency for HCH and ClB removal was monitored over 12 months.
• Genes involved in HCH degradation were analyzed to understand removal pathways.
• Diatom community structure and abundance were assessed as indicators of water quality.

Main Results:

• The Wetland+ system achieved an average removal efficiency of 81.7% for HCH and 96.8% for ClB within the first year.
• Evidence of biodegradation was confirmed by the presence of genes encoding enzymes for HCH degradation.
• Significant changes in diatom community composition and a marked increase in species diversity were observed in the receiving creek.

Conclusions:

• The Wetland+ system demonstrates high efficiency in removing persistent pesticides HCH and ClB.
• Pollutant removal is attributed to a combination of chemical processes and aerobic/anaerobic biodegradation.
• The system positively impacts the aquatic ecosystem, enhancing water quality as evidenced by diatom community recovery.