Journal of the Society of Agricultural Structures, Japan

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To use biogas effectively, an efficient desulfurization system is needed. Despite many detailed examinations of efficient and environmentally friendly operating conditions for desulfurization systems, the use of digested slurry has not been reported. The objectives of this study are to clarify the influences of oxygen supply, equipment temperature, and digested slurry pH on the desulfurization process. A 0.24 m³ polyvinyl chloride pipe reactor was used as the experimental equipment, and polypropylene carriers were filled inside. Using a pump, the digested slurry was sprayed upwards via a nozzle onto the surface of the filling carriers for approximately 5 min once a day. To attain 85 % or greater of the target desulfurization efficiency, it was necessary to supply 1.0 % or more oxygen into the biogas. However, because too much air dilutes the biogas, the optimal air supply rate was 1.0 %. It was necessary to maintain the equipment temperature above 20 ℃ for bacterial activity; therefore the optimal temperature was 30 ℃. To prevent heat loss, it was necessary to position the desulfurization system near the fermentation tank. High desulfurization efficiency was achieved by maintaining the digested slurry at pH 7.0, and it is suggested that an operating method that periodically exchanges some liquid is desirable.

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In a dairy farmer, it is an important index to manage the livestock weight for choosing a rearing method. It leads to a profit to know the weight both of dairy cattle and beef cattle. Conventionally, the static measurement is performed using fence or gage. In this paper, dynamic weight measurement of walking livestock is proposed utilizing adaptive filter on walking cycle. In case a livestock walks on the platform of measurement, the measurement signal cannot be expected to be constant, and contains disturbance signals caused by the movement of the livestock to be measured. In order to eliminate the disturbance signals, a walking cycle of the livestock is used to optimize the order and coefficient of adaptive filter. This adaptive filter realized that the difference of computed result and body weight fell in ±1 kg range compared with ±5 kg range of simple moving average. It is confirmed that the dynamic weight measurement has practically sufficient accuracy in experiment for dairy cattle.

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