Simple Estimation Method for Inorganic Nitrogenous Compounds Concentration in Swine Wastewater Treatment Plant Effluent

Abstract

In Japan, nitrate-related nitrogen (sum total value of NO₂^－-N, NO₃^－-N and 0.4 times of NH₄⁺-N concentration) in effluent of wastewater treatment facility is regulated by Water Pollution Control Law. Real time monitoring of nitrate-related nitrogen in the effluent would be important for its stable reduction. This study attempted to establish simple nitrate-related nitrogen estimation method using portable water quality measuring devices. Analysis of data obtained from 14 farms suggested that both multiple regression model and decision tree model with pH and EC or pH and refractive index as explanatory variables would be applicable for the estimation of the nitrate-related nitrogen. Ammonium nitrogen was predictable by EC or refractive index. Simple colorimetric pH measurement with BTB reagent was applicable instead of pH electrode method in the case of decision tree model.