Patent ID: 6146896
Filing Date: 2000-11-14
Classification: C02F,C12Q,G01N,Y10T

Abstract:
A method for determining nitrification effectiveness of activated sludge in an aqueous solution, comprising the steps of:supplying equivalent preselected quantities of an activated sludge including nitrifying bacteria, an aqueous solution, and a gas containing oxygen to each of first and second reaction vessels;simultaneously delivering a nitrification inhibitor to only the second reaction vessel in an amount which is at least effective to inhibit nitrification of the aqueous solution;performing a bacterial respiration reaction in the first and second reaction vessels for either a preselected period of time or continuously in which case the equivalent preselected quantities of activated sludge, aqueous solution, and gas containing oxygen are supplied per unit of time, so that the bacterial respiration reaction in the first reaction vessel, where oxygen consumption as a result of total bacterial respiration occurs and includes oxygen consumption as a result of endogenous respiration, oxygen consumption as a result of nitrification, and oxygen consumption as a result of degradation of carbon compounds, may be compared with the respiration reaction in the second reaction vessel where oxygen consumption includes oxygen consumption as a result of endogenous respiration, and oxygen consumption as a result of degradation of carbon compounds, but where oxygen consumption as a result of nitrification is at least inhibited;measuring oxygen content for each of the first and second reaction vessels after the same reaction time either above the respective aqueous solutions or continuously in respective waste gas streams escaping from the respective reaction vessels to obtain at least one measured value for the first reaction vessel and for the second reaction vessel of one of oxygen content or a variable derived therefrom;determining the nitrification effectiveness of the activated sludge per unit quantity thereof by subtracting one of the at least one measured value for the second reaction vessel from one of the at least one measured value for the first reaction vessel to provide a difference value;supplying said equivalent preselected quantities of an activated sludge including nitrifying bacteria, pure water, and a gas containing oxygen to a third reaction vessel;performing a bacterial respiration reaction in the third reaction vessel for either said preselected period of time or continuously in which case the equivalent preselected quantities of activated sludge, pure water, and gas containing oxygen are supplied per unit of time;measuring oxygen content for the third reaction vessel either above the water in the third reaction vessel or continuously in a waste gas stream escaping from the third reaction vessel after a reaction time which is either the same as that for the first and second reaction vessels or continuously to obtain at least one measured value of one of oxygen content or a variable derived therefrom; anddetermining biochemical oxygen demand of the aqueous solution in the second reaction vessel by subtracting respective ones of the at least one measured value for the third reaction vessel from corresponding respective ones of the at least one measured value for the second reaction vessel.