Biological arsenite oxidation with nitrate as sole electron acceptor

Area of Science:

• Environmental Microbiology
• Bioremediation
• Wastewater Treatment

Background:

• Arsenite contamination poses significant environmental and health risks.
• Anoxic bioremediation offers a sustainable approach to arsenic removal.
• Nitrate-based respiration is a common process in anoxic environments.

Purpose of the Study:

• To evaluate the efficacy of anoxic biological arsenite oxidation using nitrate as the sole electron acceptor.
• To assess the performance of activated sludge acclimatized to arsenite and nitrate co-existence.
• To determine the kinetic parameters of the arsenite oxidation process.

Main Methods:

• Cultivation of activated sludge in a sequencing batch reactor under arsenite and nitrate exposure for six months.
• Conducting batch experiments to test anoxic arsenite oxidation with nitrate and nitrite as electron acceptors.
• Kinetic analysis to determine maximum specific arsenite oxidation rates.

Main Results:

• No significant inhibition of anoxic arsenite oxidation was observed at arsenite concentrations up to 35 mg As(III)/L.
• Nitrite accumulation occurred, suggesting potential limitations in arsenite availability.
• Maximum specific arsenite oxidation rates were 0.55 ± 0.10 mg As(III)/g VSS/min for nitrate and 0.40 ± 0.04 mg As(III)/g VSS/min for nitrite.

Conclusions:

• Acclimatized activated sludge can effectively perform anoxic arsenite oxidation with nitrate.
• The process is robust at relevant arsenite concentrations, showing potential for practical application.
• Further optimization may be needed to address nitrite accumulation and enhance overall efficiency.