Low-temperature drying of Inorganic sludge, which is difficult to dry / Test cases / Sludge dryer

SUMMARY

KENKI DRYER is a dryer with a unique mechanism patented in the world, which is particularly suitable for drying sludge with strong adhesion and stickiness. The KENKI DRYER solves the problems of sludge clogging and inability to dry the inside of the sludge, which were difficult to solve with conventional dryers, and achieves smooth and uniform drying.

Main Features of KENKI DRYER: 
・Low temperature drying: Compositional changes in the dried material are minimal, making it suitable for recycling and upcycling.
・Continuous operation: 24-hour unattended operation is possible for efficient drying.
・Low cost: High thermal: efficiency of drying with steam as the heat source reduces fuel costs.
・Reduced environmental impact: Reduces carbon dioxide emissions and contributes to decarbonization.
・Easy maintenance: Low wear of parts and easy maintenance.

KENKI DRYER application examples：
・Drying of sludge in wastewater treatment plants: Reuse dried sludge as fertilizer, fuel, etc.
・Drying organic waste: Conversion into biochar or bio-coke

Advantages of KENKI DRYER：
・High drying capacity: Reliable drying of sticky and adhesive materials
・Low cost and high efficiency: Lower fuel costs, less maintenance
・Reduced environmental impact: Reduces carbon dioxide emissions and contributes to decarbonization
・Versatile: Applicable for drying not only sludge but also various organic wastes

KENKI DRYER is a revolutionary drying system that addresses environmental and resource issues. It is particularly appreciated for its high performance and environmental friendliness in sludge treatment at wastewater treatment plants and in upcycling and recycling of organic waste.

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 upcycling and recycling of sewage sludge, which is continuously discharged from wastewater treatment plants, is becoming increasingly important for environmental protection, decarbonization, and securing imported resources.

KENKI DRYER can easily and smoothly dry even highly sticky and difficult-to-dry materials. For example, highly sticky sludge is difficult to dry. KENKI DRYER’s unique, world-patented mechanism allows sludge to be dried smoothly without clogging the dryer, no matter how sticky or adhesive the sludge is, and no matter how high the water content. 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. In the drying process of the KENKI DRYER, even if the dried sludge becomes lumpy, it is crushed to a certain extent in the dryer to reduce its surface area, which allows the dried sludge to be dried more than adequately. This allows drying to the inside of the dried material.

KENKI DRYER dries sludge discharged from wastewater treatment plants at low temperatures, so the composition of the dried material remains unchanged after drying and can be used for recycling and upcycling. It 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. The KENKI DEYER uses steam as a heat source, but its high drying heat efficiency means that less steam is used. The use of excess steam is not costly in terms of fuel costs, and the dryer does not emit carbon dioxide during the drying process, allowing for decarbonized drying. Alternatively, by installing an electric boiler, no greenhouse gases or CO2 emissions are generated during drying.
The 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 rising due to the recent trucking problem in 2024, and by reducing the number of trucks used to transport waste, thereby reducing carbon dioxide emissions.

Currently, there is a shortage of wood in Japan. The use of dried organic waste as fuel instead of wood, or the use of dried organic sludge as biochar or biocoke by carbonization, is attracting much attention. For example, bio-coke can be used as a reductant or deoxidizer to replace coke in the steel and foundry industries.
Biochar and bio-coke are carbonized materials made from biological resources that are effective in revitalizing organisms and improving the environment. For carbonization, we can offer our Biogreen pyrolysis equipment, which does not use fossil fuels and does not emit CO2, a greenhouse gas, from the equipment.

KENKI DRYER can dry sticky and adhesive materials that cannot be dried anywhere else. KENKI DRYER is an epoch-making drying equipment with our original technology that has obtained a total of 11 patents (2 in Japan and 9 in 7 countries overseas). Please consider KENKI DRYER for your high moisture content organic waste dryer, sludge dryer, slurry dryer, methane fermentation digested liquid dryer, waste upcycling and recycling dryer.

KENKI DRYER has been granted 11 patents in 8 countries (Japan, Taiwan, USA, France, Germany, UK, Switzerland, Canada).

Inorganic sludge refers to the waste byproduct from industrial processes that consist mainly of inorganic compounds. These can include metals, minerals, and other non-organic substances. Inorganic sludge is typically generated from processes such as water treatment, metal finishing, mining, and chemical manufacturing.

Key characteristics of inorganic sludge include:

1. Composition: Unlike organic sludge, which is primarily composed of biodegradable materials, inorganic sludge contains substances that are not easily broken down by biological processes. Common components can include heavy metals (like lead, cadmium, and chromium), metal hydroxides, silicates, phosphates, and other mineral compounds.

2. Source: Inorganic sludge can come from a variety of industrial activities, such as:

   • Water Treatment Plants: where it results from the removal of heavy metals and other contaminants from water.
   • Metal Finishing and Electroplating: producing sludge containing metal hydroxides and other residues.
   • Mining and Ore Processing: generating sludge with high concentrations of minerals and metals.
   • Chemical Manufacturing: where various chemical reactions produce inorganic residues.

3. Handling and Disposal: Because inorganic sludge can contain hazardous materials, it requires careful handling and disposal. It may need to be treated to stabilize hazardous components before disposal, and often has to be disposed of in specially designated landfills or processed further to recover valuable metals.

4. Environmental Impact: Improper disposal of inorganic sludge can lead to significant environmental issues, including soil and water contamination. Heavy metals and other toxic substances can leach into groundwater, posing risks to human health and the environment.

5. Regulation: The management of inorganic sludge is subject to strict regulations in many countries to prevent environmental contamination and protect public health. These regulations often dictate how sludge must be treated, transported, and disposed of.

Understanding and managing inorganic sludge is crucial for minimizing its environmental impact and ensuring compliance with environmental protection standards.

Source：ChatGPT

Sludge is a solid residue produced during wastewater treatment. It can be broadly classified into two types: inorganic and organic.

Inorganic Sludge

• Composition: Primarily composed of inorganic materials such as sand, grit, and metals.
• Source: Generated from wastewater treatment facilities handling industrial effluents, construction sites, and water purification plants.
• Characteristics: High density, abrasive, and often contains toxic substances.
• Treatment: Typically involves physical and chemical processes like sedimentation, coagulation, and filtration.

Organic Sludge

• Composition: Mainly consists of organic matter like bacteria, microorganisms, and decomposed organic waste.
• Source: Produced from sewage treatment plants, food processing industries, and paper mills.
• Characteristics: High water content, foul odor, and potential for pathogen presence.
• Treatment: Often involves biological processes like aerobic or anaerobic digestion, followed by dewatering and drying.

Key Differences

Feature	Inorganic Sludge	Organic Sludge
Composition	Inorganic materials	Organic matter
Source	Industrial effluents, construction sites	Sewage, food processing, paper mills
Characteristics	High density, abrasive	High water content, foul odor
Treatment	Physical and chemical processes	Biological processes, dewatering, drying

Note: In many cases, sludge is a mixture of both inorganic and organic components, requiring a combination of treatment methods.

Source：Gemini

Dehydrated sludge refers to sludge that has undergone a process to remove a significant portion of its water content. Sludge is a byproduct of wastewater treatment, consisting of a mixture of water, organic and inorganic materials, and microorganisms. Dehydrating sludge reduces its volume and weight, making it easier and more cost-effective to handle, transport, and dispose of.

The process of dehydrating sludge typically involves several stages:

1. Thickening: Concentrates the sludge by removing some of the water, usually through gravity or flotation thickening.
2. Conditioning: Adds chemicals to the sludge to improve its dewaterability.
3. Dewatering: Removes additional water through mechanical means, such as centrifuges, belt filter presses, or screw presses.
4. Drying: Further reduces moisture content using thermal methods, such as drying beds, ovens, or dryers.

Dehydrated sludge can be further processed or disposed of in several ways, including incineration, landfilling, or use as a soil conditioner or fertilizer after proper treatment.

Source：ChatGPT

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

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.

Source：Gemini

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.

Source：ChatGPT

• Material to be dry: Inorganic sludge
• Purpose of drying: Reducing industrial waste cost and amount
• Moisture content: 55.4％W.B. before drying, 6.3％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

Competitive comparison

Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Precious metals, particularly the noble metals, are more corrosion resistant and less chemically reactive than most elements. They are usually ductile and have a high luster. Historically, precious metals were important as currency but are now regarded mainly as investment and industrial raw materials. Gold, silver, platinum, and palladium each have an ISO 4217 currency code.

Source：Wiki Precious metal

The term “minor metal” refers to a broad range of metals that are not traded on formal exchanges, such as the London Metal Exchange (LME). These metals are often extracted as by-products of base metal smelting and have relatively low annual production volumes compared to base metals. They are used in various high-tech applications, including electronics, solar panels, and batteries.

Some examples of minor metals include tungsten, titanium, cobalt, molybdenum, indium, niobium, and rare-earth elements. These metals are critical to modern technology and are used in a wide range of industries, including pharmaceuticals, semiconductors, automotive, glass, and solar energy.

Source：Perplexity

An urban mine is the stockpile of rare metals in the discarded waste electrical and electronic equipment (WEEE) of a society. Urban mining is the process of recovering these rare metals through mechanical and chemical treatments. In 1997, recycled gold accounted for approximately 20% of the 2700 tons of gold supplied to the market.

The name was coined in the 1980s by Professor Hideo Nanjyo of the Research Institute of Mineral Dressing and Metallurgy at Tohoku University and the idea has gained significant traction in Japan (and in other parts of Asia) in the 21st century.

Research published by the Japanese government’s National Institute of Materials Science in 2010 estimated that there were 6,800 tones of gold recoverable from used electronic equipment in Japan.

Source：Wiki Urban mining

Mineral resources are naturally occurring, solid, inorganic substances with a specific chemical composition and a characteristic crystal structure. They are essential for our modern way of life. Over 95% of the energy we use, 80% of industrial raw materials, and 70% of raw materials for agriculture come from mineral resources.
There are over 2,000 identified minerals, and they can be broadly classified into two categories: metals and non-metals.

Metals are lustrous, ductile, and malleable. They are good conductors of heat and electricity. Examples of metals include iron, copper, gold, and silver.

Non-metals are all minerals that are not classified as metals. They have a wide variety of properties and are used in a wide variety of applications. Examples of non-metals include diamond, sulfur, salt, and limestone.

Source：Gemini

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

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.

Products

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.

Methods

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

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