Regarding the determination of the overall dimensions of the sewage treatment reaction tank

Aeration tank? This is not difficult to find and is introduced in many books. I can't explain it clearly in a sentence or two. It is recommended to refer to "Principles and Design of Environmental Protection Equipment" published by Sinopec Press (edited by Chen Jiaqing), which contains specific designs. This post was last edited by Fightinghard on 2009-2-25 13:17 ]

The volume of the reaction tank is generally designed according to the residence time of 5-20 minutes.

There is no need for an aeration tank, a stirrer reaction is also possible.

In fact, what I want to know more is how to distribute the length, width and depth under a certain volume to meet the residence time.

The poster is right, I'm just giving an example. The relevant design books are basically all there, and I guess you can find almost all the relevant books.

The type of reaction pools mentioned by LZ can be found in the design books. The design of the pool type and hydraulic retention time is closely related to the mixing method and the terrain. If mechanical mixing is used, square, rectangular or round shapes can be used. If air mixing is used, rectangular shape is better. If gravity or subsurface flow mixing is used, rectangular shape is still better. The hydraulic retention time is also related to the mixing method, and mechanical mixing is shorter. The water depth is the same, and the general design water depth is 2-3 meters.

To make a plan for the landlord, it is necessary to build two pools. The first one is a mixing pool with a residence time of 2 minutes and a vertical mixing equipment. The depth is determined according to the size of the mixing equipment, generally around 2m. The mixing pool is best made into 2 cells. In order to prepare for maintenance, production will not stop. The second is a sedimentation tank or clarification tank, with a general residence time of 2-3 hours. Clarifiers are recommended. If a mechanical stirring clarifier is used, there is a standard atlas for reference. If the sludge needs to be dewatered, a sludge treatment system is also required, including a sludge drainage tank, a sludge pump room, a dewatering machine room, a dosing room, etc. This post was last edited by Shui Suiyuanbo on 2009-2-26 11:22 ]

First determine the pool capacity based on flow and residence time. Generally, for air aeration systems, a depth of 6 meters is more economical. The setting of length and width is basically 4 according to the design guidance of Shanghai Municipal Council.: 1, but it is not necessarily arranged this way now, it must be based on the actual venue. The width now generally does not exceed 10 meters.

Please tell me about the 4 mentioned above.: What is the reason for 1?

Try it yourself to determine the dwell time or processing load, aspect ratio, etc. Refer to the design manual

I read that the aspect ratio of the sedimentation tank in the "Water Supply and Drainage Design Manual" is greater than 4: 1, so I don’t know if it is applied to the reaction pool? Also, the designs given in the "Water Supply and Drainage Design Manual" are all grids, sedimentation tanks, sedimentation tanks, and no reaction tanks. I know that once the flow rate and hydraulic retention time are determined, the pool volume is determined, but how to allocate a reasonable ratio of length, width, and depth? I can't find this in the design manual. So I think what you are telling you is based on the manual, instead of just telling me to check the manual. I am not lazy myself:handshake

Let me try to answer this question. There is generally no design for this stirred reaction tank in the design manual, at least I haven't seen it yet. Judging from the current operating experience, a circular pool design is the most suitable. There are two main reasons:: 1. Square water inlet and outlet and mixing are difficult to achieve evenly ； 2. Square slag removal is inconvenient ； The design method you determined is correct: Hourly flow x residence time. The residence time is generally 10-20min, usually 15 or 20. It must not be less than 10, (the addition is lime slurry), and the dry material should be appropriately extended. Central mixing is used for mixing, and the depth of the pool is 4-6m. If you really want to use a square shape, that’s fine. A square shape is the best!

In addition, the lime slurry should be added from the bottom of the pool, out of the water, to the top of the pool and below the water surface for about 50 working minutes. The effect is already very good if the pH is around 10, so the amount of lime slurry does not need to be too large.

Thank you brother for your reply. What I want to design is actually the wastewater treatment of phosphoric acid chemical industry. The flow rate is actually about 6.25 M3/h. So even if I calculate the residence time as 1 hour, the volume will be 6.25M3. So it is impossible to get it to 3-4 meters deep. Haha, I didn't explain the situation clearly before. Another question is that the design of the inclined plate sedimentation tank at the back is a bit confusing? The surface load q' of the primary inclined plate sedimentation tank is taken to be 1.5m3/(m2.h), the tank area F=6.25/1×1.5×0.91=4.58 m2, the side length of the tank a=4.581/2=2.14m, and the residence time in the tank (t): Suppose h2=0.7m h3=1×sin60=0.866mt=(0.7+0.866)×60/1.5=62.64min. In this way, the residence time in the pool is much longer than the design requirement of "the primary sedimentation tank does not exceed 30 minutes and the secondary sedimentation tank does not exceed 60 minutes." If the surface load q' is about 3, the residence time in the pool is short, but the area F of the pool is only 2.3m2. I think the actual processing effect should be very poor. .

Haha, the main reason for the original poster is that I have never seen a small pond, so I can calculate the number it should be. Don’t doubt it, it is normal for the pond to be small. Generally speaking, the longer the residence time of the mixing tank and sedimentation tank, the better. Others say that the retention time should not be exceeded mainly to save land and investment. For example, the inclined tube sedimentation tank generally chooses 45 minutes, but the hydraulic load must not be too large. The general design principle is to choose two ends, that is to say, the middle value of the load is too small, and the residence time or pool capacity is too large. For the stirred reaction tank, the reaction effect will be better if the tank depth is larger, so it is recommended that you choose the effective tank depth to be no less than 4m. If your water volume is small, the pool will certainly be small. Don’t worry about the small size of the pool. There are many domestic sewage treatment pools in Jiangsu and Zhejiang areas ranging from a few square meters to dozens. The effect is the same, as long as its hydraulic load and residence time are met. It’s just that if the pool is small, you should pay attention when choosing a pump to avoid uneven water distribution and short flow. Also, I usually take the hydraulic load of the inclined pipe to 1.2, please take a look. It doesn’t have to be exactly in accordance with the design manual. In general projects, it needs to be enlarged. But don’t stray too far from the design manual.

Suggestion: Call a professional sewage treatment company for consultation

You're welcome, brother, I will ask you for advice on other aspects in the future.