Sludge Dryer

Sludge dryers dry wastewater sludge to reduce its mass and save on sludge transportation and disposal costs. Dried sludge is easy to handle and store, all further processing and utilization methods are possible, and the dried product can be used as fertilizer and fuel.

KUOSI is a manufacturer and supplier of sludge dryer machine in China. The manufactured sludge dryers are designed for small, medium and large sludge generating units. These dryers can be installed to load directly underneath a filter press or multiple disk screw press, or elsewhere in the plant. The sludge is dried through the heated liner of our units while being crushed and circulated through our screw blade system. The dryer liner uses an indirect heat source from steam, electric hot plates or gas fires. Our pre-heated airflow system draws moisture out of the top of the internal dryer and discharges it through our wet scrubber system. Typically after 3-6 hours of drying time (depending on the type and moisture content of the sludge), the dried material is removed for gravity discharge into a container by simply opening the discharge panel below the unit. Another option is to include a screw conveyor to move the sludge into the elevated container.

Our use and indirect heating provides a uniform heating surface and allows for tighter temperature control, making it less likely to cause sludge burning or insidious combustion. It also eliminates the dangers associated with open flames.

Purpose of sludge drying

The limitations of mechanical sludge drying sometimes require thermal drying through water evaporation. Drying sludge makes it suitable for recycling or destruction, allowing the sludge to be recycled for a variety of uses, such as fertilizer, compost by-products or fuel for incineration plants.

  • Weight and volume reduction
    Removing water from sludge by evaporation reduces the volume and weight of sludge, making it easier to store and transport.
  • Stabilization of sludge
    Drying stabilizes sludge, thereby reducing olfactory nuisance and improving disinfection.
  • Easier recovery
    By evaporating the water, the end product can be prepared for use in a composting facility. This means that the sludge can be recycled for agricultural use.
  • Easier sludge treatment
    Drying can reach the minimum dry content levels required by law for use in cement plant ovens. It also increases the calorific value of the sludge used for incineration.


  • Chemical sludge
  • Industrial sludge
  • Hazardous sludge
  • Municipal sludge
  • Food waste
  • Other high moisture and viscosity materials



Sludge dryer is an indirect heating and low speed stirring type dryer. There are two or four hollow rotating shafts inside the equipment. The hollow shafts are densely arranged with wedge-shaped hollow blades in parallel. The structure design is special and ingenious. The shaft body rotates relatively, and the self-cleaning effect of the sludge on the shaft body is cleverly achieved by using the principle and structure of the same angular velocity but different linear velocity, and the “shaft holding” phenomenon in the sludge drying process is prevented to the maximum extent.

  1. First of all, according to the status of the site sludge, we can select the type of plate and frame filter press for filtration, so that the moisture of the sludge can be reduced from more than 90% to about 80% to 70% (according to the current situation), if the sludge is loose granular, you can choose the folding screw dewatering equipment, (dehydration effect is the same as above).
  2. When the sludge moisture is controlled at 80%-70%, then the drying equipment can be used to dry, the equipment heat source is recommended to use steam (low energy consumption), can reduce the moisture to 40%-30%(individual requirements), can also reduce the moisture lower, according to the output requirements, sludge in the equipment residence time.
  3. Feeding and discharging can be selected according to site requirements, such as belt feeding and discharging.

The purpose of sludge drying bed is dehydration, is to further reduce the water content, so that the solid content of sludge is maintained at about 20%. It can then be treated like a solid material. Sludge drying beds provide an easier way to dehydrate. In this process, the digested sludge is spread over an open bed of sand and then dried by a combination of evaporation of the sand and gravity drainage.

Sludge compost is a good soil amendment. When compost is used on farmland, it increases organic matter, improves soil structure, reduces fertilizer use, and reduces potential soil erosion.

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