Sludge dewatering process, odorous, liquid or semi-solid formed after wastewater treatment is the name given to the physical methods applied in order to reduce the moisture content of the sludge, which contains an average of 0.25% to 12% solid matter depending on the type of treatment applied.
Thanks to these methods, the percentage of moisture is reduced and thus the mud cake, which is converted into a solid state, becomes easy to transport. Thus, the sludge is made suitable for disposal and in the light of this, with the help of dewatering process, it becomes odorless and unsuitable for putrefaction and decreases in volume.
Sludge Dewatering Methods
There are many methods that can be used to dewater the sludge and each of these methods is similar to a certain extent. Therefore, it would be more logical to divide the methods into subheadings under two main headings.
Sludge dewatering methods are basically divided into two as natural and mechanical. However, these two main headings are also divided into subheadings.
Natural Dewatering Methods
Sludge Drying Beds
Sludge drying beds, which are generally preferred to be established in regions with dry climates and can be considered cheaper than other methods, consist of a porous filter media with sand and gravel layers and filtration pipes.
In this method, sand and gravel layers are placed in the filter media in such a way that the particle size grows from top to bottom.
Mud Lagoons
This method, which is used in fixed areas where the odor problem is low, is basically a system in which the fixed sludge is pumped into a natural lagoon and the sludge is dewatered, and in this method, the sludge is collected at the bottom of the lagoon and removed at certain periods, while the rested upper layer water is periodically sent to the treatment plant.
Mechanical Dewatering Methods
Vacuum Filtration
In the vacuum filtration process, which is accepted as the oldest mechanical method among the methods that have survived from the past to the present, the system consists of sludge feeding pumps, chemical feeding equipment, sludge conditioning tank, filter drum, cake conveyor or scraper, vacuum system and filtration tank systems.
Belt Press
In belt press filter systems, which act according to the principle of removing water from the sludge under pressure, sludge is fed regularly and dewatering is performed within the internal basic principle. These include chemical conditioning, drainage due to gravity and mechanical pressure application.
Filter Press
The Filter Press method, which is sometimes in a disadvantageous position due to the high amount of chemical addition and the need for manpower, consists of serial plates located within the frame of the press filters and pressed to each other hydraulically or electromechanically.
Decanter (Centrifuge)
The decanter (centrifuge) dewatering method, which is based on the sludge settling principle, works according to the system of obtaining the liquid and the cake separately, and is based on the principle of taking the sludge into the pump with the help of the feed pump and discharging it out with the drum to which the pump is connected.
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