Abstract: A moisture content measurement method that calculates moisture content of dehydrated sludge using a calibration curve for calculating the moisture content of the dehydrated sludge, the calibration curve being obtained by performing multivariate regression analysis after first-order differential processing or an offset correction is performed on absorbance for reflected light or reflectance for infrared rays from dehydrated sludge, the absorbance or the reflectance being obtained by measuring the dehydrated sludge using an infrared measurement apparatus provided with a light-receiving unit that can receive at least infrared rays reflected from a target object to be measured and a light source that has a plurality of infrared LEDs that can emit infrared rays having respectively different wavelengths or a light source having an infrared-region tungsten lamp or halogen lamp.

Abstract: The present invention provides a nitrogen treatment method which can suppress the production of nitrate nitrogen to stabilize the concentration of nitrite nitrogen in a nitritation treatment in which ammoniacal nitrogen is biologically oxidized to produce the nitrite nitrogen. A nitrogen treatment method includes a nitrification treatment step of producing nitrite nitrogen by oxidizing ammoniacal nitrogen contained in water to be treated, using microbial sludge, wherein: a volume load of the ammoniacal nitrogen in the nitrification treatment step is set to a high load of 0.3 kg-N/m3·day or more and 5 kg-N/m3·day or less; and in the nitrification treatment step, at least one of a treatment of adjusting a pH of the water to be treated to pH 8 or more and pH 10 or less and a treatment of applying an inactivating operation for sterilizing microorganisms or causing bacteriostasis to the microbial sludge is performed.