Electrochemical nitrite sensing for urine nitrification.

Area of Science:

• Environmental Science
• Analytical Chemistry
• Biotechnology

Background:

• In-situ nitrite monitoring is crucial for wastewater treatment process control, especially for high-nitrogen wastewaters.
• Existing methods like online analyzers and spectrophotometric sensors have significant limitations including sample preparation, cost, and interferences.
• Amperometric nitrite sensing presents a promising alternative for accurate and simplified monitoring.

Purpose of the Study:

• To assess the viability of an amperometric nitrite sensor for in-situ monitoring in wastewater treatment.
• To determine the sensor's performance in urine nitrification systems and ex-situ experiments.
• To establish the critical nitrite concentration range for nitrite-oxidizing bacteria and set sensor measurement targets.

Main Methods:

• Investigated an amperometric nitrite sensor in a urine nitrification reactor and through ex-situ experiments.
• Determined critical nitrite concentrations for nitrite-oxidizing bacteria (12-30 mgN/L at pH 6-6.8) via theoretical and practical approaches.
• Evaluated the sensor's sensitivity and reliability for concentrations up to 50 mgN/L, considering ambient condition influences.

Main Results:

• The amperometric sensor reliably measured nitrite concentrations between 5-50 mgN/L and higher.
• Influences of temperature, pH, conductivity, and aeration rate within expected ranges were negligible.
• The sensor demonstrated insufficient sensitivity for low nitrite concentrations typical of municipal wastewater.

Conclusions:

• The amperometric nitrite sensor effectively detects critical nitrite concentrations in high-strength nitrogen conversion processes, such as human urine nitrification.
• This sensor offers a viable solution for process control where existing technologies fall short.
• The sensor's reliability in the 5-50 mgN/L range makes it suitable for specific wastewater treatment applications.