Nitrosomonas sp. Based biosensor for ammonium nitrogen measurement in wastewater

Abstract

A bacterial culture of Nitrosomonas sp. was isolated from a nitrifying biofilm to construct a biosensor for ammonium nitrogen (NH ⁺₄ −N) measurements in high ammonia wastewaters. The pure culture of microorganisms was immobilized into agarose gel matrix to attain a stable biosensor with a long service life. Biosensors were calibrated using (NH₄)₂SO₄ solution and a steady-state method. Subsequently, several experiments with synthetic and industrial wastewaters were conducted. A linear range up to 20 mg/L of NH ⁺₄ −N, and sensitivities between 0.030 and 0.036 were gained with biosensors. During 14 days of stable service life of the Nitrosomonas sp. biosensors, variation of the signal was less than 7%. Response times of biosensors were 15 ∼ 25 min, while recovery times were up to 25 min. Measurements with high ammonia content synthetic and industrial wastewaters were conducted, and 8.3 and 5.6% over estimation of NH ⁺₄ −N was gained, respectively, compared with results of Nessler method. In spite of the small overestimation, the biosensor based on a pure culture of Nitrosomonas sp. and calibrated with (NH₄)₂SO₄ is suitable for the analysis of NH ⁺₄ −N in high ammonia content wastewaters.