JPH0420678B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of operating a fermentation apparatus, and more particularly to a method of operating an aeration device for a fermentation chamber. As a fermentation apparatus for fermenting sewage sludge and a method for operating the same, the apparatus described in Japanese Patent Application Laid-Open No. 109499/1988 is known, and has been implemented by the applicant and has achieved certain results. However, in the above-mentioned fermentation apparatus, the exhaust gas from the fermentation chamber is accompanied by fine dust generated when the material to be fermented is crushed, and countermeasures are required. In view of this, the present invention provides a method for operating a fermentation apparatus that reduces the amount of fine dust emitted during exhaust gas and promotes fermentation without inhibiting it. In order to meet the above objective, the operating method of the present invention is characterized by temporarily stopping the air supply and exhaust to the fermentation chamber from the middle stage to the lower stage during a turnaround where the generation of fine dust and its diffusion into the air are significant. . In other words, the inventors discovered that in a multi-stage fermenter, when the shelves are sequentially opened and closed from the upper stage to the lower stage, and the fermented material is dropped and turned over, the moisture content increases as fermentation progresses, organic matter decomposes, and water evaporates. When the temperature decreases, fine dust will fly up from the fermented material, and when air supply and exhaust are performed in this state, the fine dust will be carried away with it, causing problems with ventilation or deodorization equipment. We considered temporarily stopping the supply and exhaust of the stage and restarting the supply and exhaust when the fine dust had settled down after turning. One method is to temporarily stop the air supply and exhaust for all the relevant stages where the falling work is performed, but if this is done, aerobic conditions will be disturbed during this period. Therefore, it is most preferable to temporarily stop the air supply and exhaust from the middle section to the lower section where the moisture content of the object to be treated is decreasing and dust generation is significant. This means that the rate of oxygen utilization is high at the beginning of fermentation, and as the fermentation progresses, the rate of oxygen utilization decreases, so it makes sense to temporarily stop supply and exhaust from the middle stage onwards. The present invention will be explained below based on illustrated embodiments. In the figure, 10 is a fermentation device for fermenting sewage sludge, and this device is provided with a large number of fermentation chambers in a multi-stage manner so that the material to be fermented can be efficiently fermented. That is, a large number of fermentation chambers 1A are arranged in parallel in both vertical and horizontal directions on the top stage, fermentation chambers 1B are arranged on the second stage, and fermentation chambers 1C, 1D, . In this case, there are 10 stages, but the number of stages is not limited), and the fermentation chambers of each stage are on the same plane, and a bottom plate 2A that can be opened and closed is provided at the bottom of each stage of fermentation chamber, and A ventilation path is formed in the bottom plate 2A and the partition walls 3A provided in the fermentation chambers of each row of fermentation chambers arranged in parallel. The purpose is to ensure that fermentation can be carried out efficiently, and that the bottom plate is opened from the upper stage to the lower stage so that the fermented materials can be mixed and agitated as they fall. Also fresh air is blower 4
The air is then supplied to an air duct 5 that stands upright along the side wall of the fermentation device 10. This air duct 5
is branched into the upper space of the bottom part 1A, 1C, 1E...1I of each stage fermentation chamber every other stage, and is connected to the gate valves 5a, 5.
b...Connected to the processing tank via 5e. The exhaust air duct 6 is a branch pipe connected to the bottom 2A, 2C...2I of the treatment tank on the opposite side of the suction air duct at every other stage via gate valves 6a, 6b, 6c... to join. In this way, fresh air is supplied to the fermentation chambers of each stage as regulated by the gate valves 5a to 5f, and the exhaust pipes are connected to the fermentation chambers through the exhaust gate valves 6a to 6e provided on the opposite side from the supply side and one stage above and below. The whole fermenter has a laminar flow with air flowing through each stage of fermentation chamber.
Normally, it is operated as described above, and the flow of fresh air is controlled by adjusting the gate valves for supply and exhaust using air measuring instruments such as oxygen concentration meters, carbon dioxide concentration meters, and thermometers installed at each stage. This has the advantage of being able to easily and reliably promote the fermentation of waste and produce fully matured compost in a short time and in a small space. However, as fermentation progresses in the fermenter, the fermented material dries due to fermentation heat and ventilation, and its moisture content decreases. In addition, the particle size of the fermented material decreases, and at the same time, the amount of fine dust of 100 μm or less increases. For this reason, the amount of fine dust accompanying the exhaust gas increases as you go to the lower fermentation chamber, and at the lowest stage, even during normal operation, the amount of fine dust per unit displacement reaches 1 mg/m ² , and when switching back, the value increases to 100. increase twice. Therefore, during normal operation, there is a risk that the deodorizing device downstream of the exhaust pipe will be adversely affected when turning the exhaust pipe.

【table】

[Table] The preceding table shows the properties of the fermented material when it falls into the fermentation chamber at each stage before and after charging into the fermentation apparatus 10. As is clear from this data, if ventilation is continued after the middle stage, that is, during the 4th to 10th stages, the amount of dust entrained is extremely large. Therefore, if the ventilation from the lower stage, preferably the middle stage and beyond, where a large amount of dust is generated and a small amount of oxygen is consumed, is stopped at the time of switching, the fine dust entrained in the exhaust air will be reduced to the level during normal operation.

[Brief explanation of drawings]

FIG. 1 is a front view, and FIG. 2 is an air flow sheet diagram. 10...Fermentation device, 1A, 1B, 1C...1N
...Fermentation chambers at each stage, 2A, 2B, 2C...2N...
...Bottom plate, 3A...Partition wall, 4...Blower, 5...Air duct for air supply, 6...Air exhaust duct, 5a, 5b, 5c to 5f...Gate valve for air supply, 6a, 6b , 6c to 6e...exhaust gate valves.

Claims (1)

[Claims] After adjusting the water content of the sewage sludge, it is supplied from the upper stage of a multi-stage fermenter consisting of a large number of small chambers, and is sequentially dropped into the lower fermentation chambers for aerobic fermentation. In a fermentation device that performs aerobic fermentation by aerating the fermented material, when turning the fermented material down to the lower stage,
It is characterized by temporarily stopping the air supply and exhaust to the fermentation chambers from the middle to the lower tier, which contain the fermented material whose moisture content has decreased as fermentation progresses, and after turning over, supplying and exhausting is carried out after fine dust has settled down. How to operate fermentation equipment.