Abstract: A method and apparatus for determining nitrification effectiveness of activated sludge in an aqueous solution, includes supplying equivalent quantities of an activated sludge, 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; performing a bacterial respiration reaction in the vessels for either a preselected period of time or continuously in which case the materials 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 endogenou

Abstract: A method for determining constituents in water, in particular the content of organic carbon and/or nitrogen, in which an aqueous sample is evaporated and combusted in at least one heating vessel (154a) provided with a heater (154), and the combustion product is delivered in a transporting gas stream to a detector (142) for determining the concentration of a gaseous compound of the constituent, wherein the heating vessel, or a first heating vessel, at the instant of delivery of the aqueous sample has a temperature below or at most within the range of the boiling temperature of the sample, and after delivery of the sample the temperature is increased, wherein the sample is heated by one and the same heater in a first step from an outset temperature below the boiling temperature to an evaporation temperature, and in a second step to a substantially higher temperature, and the combustion product is kept in closed circulation during the analysis.