Low-temperature drying of organic sludge with high moisture content, which is difficult to process/ Test cases / Sludge dryer

■ Low-temperature drying of organic sludge with high moisture content, which is difficult to process/ KENKI DRYER / Sludge dryer



KENKI DRYER is a revolutionary dryer that enables drying of highly adhesive and sticky materials, which has been difficult with conventional dryers. With a total of 11 patents (2 in Japan and 9 in 7 foreign countries), KENKI DRYER has the following features and advantages.

1. high drying capacity

  • Our unique agitator blades and low-temperature drying system enable smooth drying of highly adhesive materials such as sludge and slurry with high water content.
  • Stable continuous operation is possible without clogging inside the dryer. 2.

2) Reduction of environmental load

  • Low-temperature drying and indirect steam method reduce fuel consumption and CO2 emissions.
  • Combined with an electric boiler, the use of fossil fuels can be reduced to zero and complete decarbonization is possible.

3. economic efficiency

  • Low running costs and energy-saving design reduce electricity costs.
  • Maintenance costs are also reduced due to low wear and tear of parts.
  • Waste weight can be reduced through drying process, which also reduces waste disposal costs.

4. support for a wide variety of applications

  • Various types of high moisture content organic waste can be dried, including sludge, slurry, and food waste.
  • The dried material can be used as fertilizer, feed, fuel, soil conditioner, etc.

5. 24-hour continuous operation

  • The automatic operation system enables continuous operation 24 hours a day, 365 days a year, reducing labor costs.

The KENKI DRYER is a next-generation drying system that combines environmental load reduction, economy, versatility, and ease of use. It can be used in various industrial fields such as wastewater treatment plants, food factories, paper mills, and chemical plants.

Patented in: Japan, Taiwan, U.S.A., France, Germany, U.K., Switzerland, Canada


KENKI DRYER is an epoch-making drying system that can dry sticky and adhesive materials that cannot be dried anywhere else, and has obtained a total of 11 patents (2 in Japan and 9 in 7 foreign countries) for its unique technology.

KENKI DRYER can easily and smoothly dry difficult-to-dry materials with strong adhesion and stickiness. For example, sticky sludge is difficult to dry. KENKI DRYER’s unique, world-patented mechanism makes it possible to dry sludge smoothly without clogging the dryer, no matter how sticky or adhesive the sludge is and how high the water content is.
In addition, since the KENKI DRYER is a continuous low-temperature drying system, there is little change in the composition of the dried material after drying, making it suitable for a wide variety of applications.

Sludge discharged from wastewater treatment plants tends to become lumpy during the drying process due to the coagulant used in wastewater treatment. When the dried sludge becomes lumpy, the heat is not sufficiently distributed to the inside of the dried sludge and the sludge is not heated inside, so only the surface is dried and the inside is not heated and dried. In the drying process of the KENKI DRYER, even if the dried material becomes lumpy, it is crushed to a certain extent in the dryer to reduce its surface area, so that the inside of the dried material can be dried more than adequately.

By drying sludge discharged from wastewater treatment plants at low temperatures, the composition of the sludge after drying remains unchanged and can be used for recycling and upcycling. KENKI DRYER is an indirect dryer that uses steam as a heat source at low temperatures, so the composition of the dried materials after drying is little changed, and they can be fully utilized as recycled and upcycled products.

KENKI DRYER, with 11 patents in 8 countries, is an indirect steam dryer, but it is a completely unique product, different in structure from other similar indirect steam dryers. Direct-fired dryers, such as burners, emit carbon dioxide from the dryer, which is against the times in terms of environmental protection and decarbonization, and drying at high temperatures means high fuel costs, rapid wear of parts, and high maintenance costs.

Although KENKI DEYER uses steam as a heat source, KENKI DRYER does not emit the global warming gas carbon dioxide CO2 during drying. In addition, KENKI DRYER uses less steam due to its high drying heat efficiency, so you can use the steam you currently use, and if you use the excess steam, the fuel cost will not increase and the CO2 emissions will not increase compared to boilers that generate steam during the drying process. Alternatively, by installing an electric boiler, drying can be done in a decarbonized manner, without producing any greenhouse gases or CO2 emissions during the drying process.

There are no problems after start-up, and the blades of the dryer’s main body rotate at a very slow speed of 5 RPM or less, so parts wear is minimal and maintenance is easy and inexpensive. KENKI DRYER is a continuous dryer, not a batch dryer that stores and dries materials to be dried. Therefore, operation is simple and unmanned operation is possible 24 hours a day.

Drying sludge to reduce the weight and volume of waste products can contribute to environmental protection and decarbonization by reducing the cost of industrial waste, which is increasing due to the recent trucking problem in 2024, and by reducing the number of trucks transporting waste, thereby reducing carbon dioxide emissions.

Japan is almost 100% dependent on imports for its mineral resources. In the future, precious metals and rare metals in particular will continue to be important resources, and securing these resources is essential to maintaining and strengthening international competitiveness. One of the measures to secure mineral resources is the reuse and recycling of minerals contained in sludge, which will contribute to environmental protection and reduce greenhouse gas emissions. Phosphorus, which is currently imported from China, is also an indispensable mineral. Therefore, the extraction of phosphorus from sewage sludge is being promoted as a national project.
The recycling of sludge from wastewater treatment plants is becoming increasingly important for environmental protection, decarbonization, and securing imported resources.

KENKI DRYER, which can dry sticky and adhesive materials that cannot be dried anywhere else, is an epoch-making dryer with a total of 11 patents (2 in Japan and 9 in 7 foreign countries). Please consider KENKI DRYER for your high moisture content organic waste dryer, sludge dryer, slurry dryer, methane fermentation digestate dryer, and waste recycling dryer.
KENKI DRYER has been granted 11 patents in 8 countries (Japan, Taiwan, USA, France, Germany, UK, Switzerland, Canada).





waste reduction sludge drying sludge dryer kenki dryer 29.06.2024


KENKI DRYER sludge drying slurry drying waste drying top 01


■ What is Organic?


“Organic” can refer to a few different things, depending on the context:

1. Organic Chemistry: In science, “organic” relates to organic chemistry, which is the study of carbon-containing compounds. This includes a vast range of substances, from fuels and plastics to DNA and proteins.

2. Organic Agriculture: In the context of agriculture and food production, “organic” refers to the methods and standards of growing and processing food. Organic farming typically avoids synthetic chemicals such as pesticides and fertilizers. It emphasizes sustainable practices, soil health, and animal welfare.

3. Organic Food: Foods labeled as organic are produced according to certain standards. In the United States, for example, the USDA (United States Department of Agriculture) has specific criteria that products must meet to be labeled as “organic.” These standards include the use of organic seeds, no synthetic fertilizers or pesticides, no genetically modified organisms (GMOs), and certain standards for animal welfare.

4. Organic in Everyday Use: Sometimes, “organic” is used more loosely to describe things that are natural or free from artificial additives, though this use can be more subjective and less strictly defined.

In summary, “organic” generally implies natural, sustainable, and health-conscious methods and products, whether referring to chemistry, farming, food, or other areas.



■ What is sludge?


Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. It can be produced as a settled suspension obtained from conventional drinking water treatment, as sewage sludge from wastewater treatment processes or as fecal sludge from pit latrines and septic tanks. The term is also sometimes used as a generic term for solids separated from suspension in a liquid; this soupy material usually contains significant quantities of interstitial water (between the solid particles). Sludge can consist of a variety of particles, such as animal manure.

Source:Wiki Sludge


■ Reasons for drying sludge


There are several key reasons why sludge, often produced as a byproduct of wastewater treatment, needs to be dried:

  • Volume Reduction: Sludge typically contains a high percentage of water. Drying significantly reduces this water content, leading to a much smaller volume. This makes transporting and storing the sludge far more manageable and cost-effective.

  • Disposal and Further Treatment: Dried sludge can be easier and safer to dispose of compared to wet sludge. For instance, dried sludge can meet specific regulations for incineration or landfilling. In some cases, drying can also be a precursor to other treatment methods.

  • Resource Recovery: When properly dried, sludge can be repurposed for beneficial uses. This could involve using it as a soil conditioner or even converting it into a fuel source.

  • Pathogen Reduction: Drying can help reduce the number of harmful pathogens present in the sludge. This makes it a safer material to handle and potentially reuse.

  • Odor Control: Wet sludge can be quite odorous. Drying helps to stabilize the sludge and significantly reduces unpleasant smells.



■ Why sludge drying is difficult?


Sludge drying is a challenging process due to several factors that complicate its efficient and effective execution. Here are the main reasons why sludge drying can be difficult:

  1. High Moisture Content:

    • Initial Moisture Levels: Sludge typically has a very high initial moisture content (up to 98% water), which requires significant energy to reduce.
    • Bound Water: Some water in sludge is chemically bound to particles, making it harder to remove through conventional drying methods.
  2. Energy Requirements:

    • High Energy Consumption: Drying sludge to a low moisture content requires substantial energy, especially for thermal drying processes.
    • Cost: The energy costs associated with sludge drying can be high, impacting the overall economics of the wastewater treatment process.
  3. Complex Composition:

    • Variable Composition: Sludge composition can vary widely depending on the source and type of wastewater being treated. This variability can affect drying efficiency and the selection of appropriate drying technologies.
    • Presence of Inorganic and Organic Materials: The mixture of organic and inorganic materials in sludge can complicate the drying process.
  4. Handling and Processing:

    • Sticky and Viscous Nature: Wet sludge can be sticky and viscous, making it difficult to handle, transport, and process in drying equipment.
    • Clogging and Fouling: Sludge can clog or foul drying equipment, requiring frequent maintenance and cleaning.
  5. Environmental and Health Concerns:

    • Odor Emissions: Drying sludge can produce unpleasant odors, which need to be managed through odor control systems.
    • Air Pollution: Thermal drying processes can release volatile organic compounds (VOCs) and other air pollutants, necessitating air pollution control measures.
  6. Equipment and Technology:

    • Specialized Equipment: Sludge drying often requires specialized equipment, such as belt dryers, drum dryers, or fluidized bed dryers, which can be expensive to purchase and maintain.
    • Operational Complexity: Managing the drying process requires skilled operators to ensure optimal performance and to address any issues that arise during operation.
  7. Disposal of By-products:

    • Residual Waste: Even after drying, there is still a need to dispose of the dried sludge or its ash if incinerated, which can involve additional costs and regulatory compliance.
  8. Regulatory Compliance:

    • Stringent Regulations: There are often strict regulations governing the drying and disposal of sludge, particularly concerning emissions and pathogen reduction, which can add complexity to the process.

In summary, sludge drying is difficult due to high moisture content, significant energy requirements, complex sludge composition, handling challenges, environmental and health concerns, specialized equipment needs, and stringent regulatory requirements. These factors make sludge drying a technically and economically challenging process in wastewater treatment.



KENKI DRYER sludge drying slurry drying waste drying top 02


Woman illustration organic sludge drying kenki dryer organic sludge dryer 29.06.2024



■ Low-temperature drying of organic sludge with high moisture content, which is difficult to process / Test cases




■ Low-temperature drying of organic sludge with high moisture content, which is difficult to process / Test result 


  • Material to be dry: Organic sludge
  • Purpose of drying: Reducing industrial waste cost and amount
  • Moisture content: 85.7%W.B. before drying, 10.8%W.B. after drying
  • Requirements for dryer: To prevent clogging inside the dryer caused by the stickiness and adhesiveness. Automated continuous operation with no operator attended.
    Machine cost can be recovered in short term.
  • Test result: OK

sludge drying before and after kenki dryer sludge dryer 29.06.2024


Sludge drying

Competitive comparison


■ Self-cleaning screw / Steam Heated Twin Screw Technology
( SHTS technology )


One of the International Patented Technology that KENKI DRYER has is a self-cleaning structure called Steam Heated Twin Screw technology (SHTS technology). No matter how materials are sticky, adhesive and viscous is, they can be dried without clogging inside of the dryer because of this unique structure that no other products has.
For example, even materials stuck to the blades of one screw, blades of the other screw in the dryer’s body forcibly peels the materials off as they rotate. Since the blades rotate by peeling the material off each other, any sticky, adhesive and viscous material does not adhere to the blade, and the blades continue rotating, peeling, agitating and heating material without stopping while they carries material further. Also, since surface of blades are always renewed and kept clean, heat near the blades is not blocked and it is conducted directly into the materials.

Self-cleaning screw


■ Product characteristics

KENKI DRYER has three main characteristics. They are 1) Any materials can be dried as expected including sticky, adhesive and viscous materials and raw material slurry that no other company can deal with, 2) dried material can by recycled or utilized as raw materials because of its low-temperature drying method, and 3) there is no need to assign operator since its continuous operating system makes 24 hours unattended operation possible.



■ Drying process


The unique and original drying mechanism of KENKI DRYER is also International Patented Technology. Because 4 drying mechanisms which are crashing drying, agitation drying, circulation drying and indirect drying work simultaneously and add heat to material being dried repeatedly and continuously, inner part of the material is dried thoroughly and quality of discharged material after drying is stable. This series of drying mechanisms prevents agglomeration which causes insufficient drying from feeding process of the material into the dryer until discharging process after drying completed. Various ingenuities to conduct heat surely into inner part of the materials are exercised and stable heating and drying are proceeded continuously.



■ Heat source, Saturated steam


Even KENKI DRYER uses only saturated steam as its heat source, it is outstanding in safety and hygiene point of view with its unique drying mechanism based on combined use of conductive heat transfer method and heated air method. Since steam is a stable heat source, quality of discharged material after drying is also stable and equable. Maximum allowed steam pressure is 0.7Mpa and adjustment of steam pressure, adjustment of drying temperature in other words, can be easily done. Saturated steam is commonly used in many factories so that it can be said as a familiar and handy heat source. In comparison with drying methods using burner or hot blasts, saturated steam method is an indirect drying applying heat exchange via pipes that steam is passing through, therefore, it hardly burns the materials and is outstanding in safety and hygiene point of view.

Heat source, Steam


Please consider KENKI DRYER for drying of sticky materials, adhesive materials and materials in liquid state that no other dryer can deal with.
Initial, running and maintenance costs are low because of its simple structure based on internationally patented technology.
For sludge drying, costs of our dryers are estimated to be retrieved within 2, 3 years by reducing industrial waste disposal cost.
For raw material slurry drying, laborious works of manual operation will be decreased significantly by replacing box shaped compartment tray dryer with our dryer
In case of organic wastes drying, the waste can be recycled as fuel, fertilizer, soil conditioner and feedstuff after being dried.


Company site
No more trouble. Conveyor, Industrial environmental equipment and apparatus
Pyrolyzer Biogreen
A pyrolyser with internationally patented technology which use no fire