Development of fast analyzer on biological waste´s nutrient contents

With the development of poultry husbandry, a volume of excreta from a large number of livestocks has caused serious environmental pollution problems because of the inappropriate disposal. Therefore an efficient and economical solution to the disposal of excreta from poultry is necessary with the intensification of consciousness in protecting environment. One important method is to properly use the excreta as manure in the farmland, and then estimating the nutrient contents in manure before the disposal is essential with the development of modern precision agriculture. It is studied that the nutrient contents (Nitrogen, Phosphorus, Potassium) in the excreta of animals have a correlation with the physical and chemical indexes including conductivity, specific gravity and so on. The goal of this study lays in the development of an instrument of fast measuring the biological waste´s conductivity based on the method of two-electrode passed by the constant AC current to satisfy the demand of acquiring the nutrient contents in manure. This analyzer system is mainly made up of two parts: the electrode sensor and the control circuit. The electrode sensor adopts DJS-10D to detect the variation of the excreta conductivity based on two-electrode measurement principle. The control circuit adopts the PHILIPS ARM7 chip LPC2114.The designed ARM system can perform the acquisition and processing of the conductivity-relative data, display and store. The constant AC current as the supply oscillator is added to the two-electrode sensor, and then acquire the AC voltage signal related to the excreta conductivity. Finally the conductivity data is displayed in the LCD and stored into the USB disk. Calibration test shows that the analyzer is practical.