Latest technologies for sludge dewatering
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Current environmental regulations require that wastewater treatment meet specified standards. However, the activated sludge produced also needs to have a proper destination; otherwise, secondary pollution will occur. To properly handle sludge, concentration and dewatering are essential ； The common practice is to use a belt press for dewatering the sludge discharged from the sludge thickening tank ； After dewatering, the solid content of the sludge is below 20% ； It is far from meeting the requirements for reprocessing. Therefore, there are many manufacturers of equipment for further mechanical dehydration, but there are few practical engineering examples, especially in large-scale industrial production, where equipment with low energy consumption, automated operation, and a low failure rate is essential. Using steam drying results in the highest energy consumption, so it is the only option when no other choice is available. Does anyone think there are good ways to dewater sludge? Also, there is now a type of spiral centrifuge that claims to allow low-concentration wastewater to be separated from sludge without the need for concentration; this eliminates the need for sludge sedimentation tanks and concentration tanks, among other things. It also has advantages such as lower energy consumption and less space requirement. I wonder if anyone has used it? This post was last edited by johncom on 2009-3-11 06:47]
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The centrifugal dewatering machine is used in the sewage treatment plant in Meishan City; it is imported from Germany and comes equipped with a sludge drying unit. However, a secondary sedimentation tank and sludge thickening process are still required. The reason for this is that sludge thickening helps to reduce the load on the dewatering machine, thereby lowering energy consumption and operational costs. I’m not entirely in agreement with what LZ said about belt filter presses. Under normal circumstances, the solid content of the sludge after treatment by a belt filter press is between 20-25%; if management is excellent, it can reach 26-28%.
Upstairs, please specify the manufacturer of the centrifugal dehydrator and the drying equipment from Germany. Thank you!
This company also produces spiral press sludge dewatering machines, and it already has a considerable number of users in China; for more details, you can contact the company directly. Shanghai Hongji Environmental Protection Engineering Co., Ltd.: hongjihb@126.com, 021-65980506, 65980507
Our company is also planning to install a stacked spiral centrifuge; previously, we only used horizontal spiral centrifuges and filter presses.
I think the spiral centrifuge isn’t very useful; as mentioned on the third floor, it consumes energy, while natural sedimentation and concentration require no energy at all, meaning there are no operational costs. The fixed capital investment is thus spread over the treatment of each ton of wastewater, resulting in very low costs. The key is still the dewatering of sludge. How can it be handled in a way that is energy-efficient, environmentally friendly, and efficient?
When it comes to choosing between screw press centrifuges, horizontal screw centrifuges, and filter presses, Lao Hu from the Water Network Forum is quite knowledgeable; you can consult him.
There is no concentration tank used now; instead, there is an integrated concentration and filtration press. But without a secondary sedimentation tank, it would be difficult to separate the sludge from the water – feeding it directly into the so-called spiral centrifuge probably won’t work. In fact, traditional secondary sedimentation tanks and sludge thickening tanks use gravity to separate and concentrate sludge, ensuring a certain quality of the sludge. They require no energy consumption, have few mechanical components, and thus incur low maintenance and operating costs; the only drawback is that they take up a lot of space. Since wastewater treatment plants are usually located in remote areas, this space requirement isn’t a major issue. Integrated mechanical systems have many advantages, but their maintenance and operating costs are certainly high. The treatment method should still be chosen based on local conditions.