Application of Turbidity Compensation Model in Total Nitrogen Water Quality Analyzer

As one of internationally recognized important indicator to measure the degree of eutrophication of water bodies, the total nitrogen represents the total content of organic nitrogen and inorganic nitrogen (NH
4
⁺
+NO
3
⁻
+NO
2
⁻
) in water. Its content can reflect the degree of pollution of water bodies. As a national standard method for measuring total nitrogen content in water, ultraviolet spectrophotometry has the advantages of high sensitivity and small error. But when the turbidity of the measured water body is high, the results of this measurement method will be severely affected, and even show negative values. In this paper, a turbidity compensation model based on full-spectrum spectrophotometry is proposed. The sensitive wavelength band that can reflect the turbidity of water is determined by experiments, and the quantitative relationship between the absorption spectrum intensity and the absorbance introduced by turbidity is established. Under this model, the 1 mg/L total nitrogen standard solution with different turbidity was tested and analyzed. The average absolute error between the predicted value and the real value was 5.25 %, indicating that this model has the potential to be applied in the total nitrogen analyzer to achieve anti-turbidity function.