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

Conclusion

KENKI DRYER is a drying system that can easily and smoothly dry even difficult-to-dry materials such as sludge with strong adhesion and stickiness. The world patented unique mechanism prevents clogging in the dryer and achieves continuous low temperature drying. This ensures minimal change in composition even after drying and allows 24-hour unattended operation.
Sludge discharged from wastewater treatment plants tends to become lumpy due to flocculants, making it difficult to dry the sludge from the inside, but the KENKI DRYER can dry it sufficiently with its crushing function. Low-temperature drying minimizes composition changes and facilitates recycling and upcycling.
KENKI DRYER uses steam for indirect drying, reducing fuel costs and carbon dioxide emissions. Operation is simple, wear and tear on parts is minimal, and maintenance costs are low.

Drying sludge reduces waste volume, saves industrial waste costs and contributes to environmental protection. In addition, the reuse and recycling of mineral resources in sludge and its use as biochar or bio-coke as a wood substitute are attracting attention.
KENKI DRYER has 11 patents in 8 countries including Japan for its innovative drying technology. It is ideal for drying high moisture organic waste, sludge, slurry, digestate from methane fermentation and waste recycling.

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, so it can be used 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, thereby ensuring that the inside of the dried sludge is sufficiently dried. This enables 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 drying, 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 its weight and the amount of waste materials 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 materials, thereby reducing carbon dioxide emissions.
Japan is almost 100% dependent on imports for 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 to reuse and recycle 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 essential mineral. Therefore, the extraction of phosphorus from sewage sludge is being promoted as a national project.
The recycling of sludge, which is a necessary part of wastewater treatment plants, is important for environmental protection, decarbonization, and securing resources that are currently dependent on imports and demand is only increasing.

Currently, wood is in short supply in Japan. The use of dried organic waste as fuel instead of wood, or the use of dried organic sludge as biochar or bio coke by carbonizing it, is attracting a great deal of attention. For example, bio coke can be used as a reductant or deoxidizer as a substitute for 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. We can provide carbonization services using our Biogreen pyrolysis equipment, which does not use fossil fuels and does not emit CO2, a greenhouse gas, so please contact us.

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).

Organic sludge refers to a semi-solid slurry that is primarily composed of organic matter. It can be generated from various sources, including:

1. Wastewater Treatment Plants: Organic sludge is a byproduct of the treatment process, primarily consisting of organic waste, bacteria, and other microorganisms that break down sewage.
2. Industrial Processes: Certain industries, such as food processing, paper manufacturing, and agriculture, produce organic sludge as a waste product.
3. Composting and Biogas Production: Organic waste material from these processes can also produce sludge.

Organic sludge typically contains a high level of nutrients, such as nitrogen and phosphorus, making it useful for agricultural applications as a soil amendment. However, it can also contain contaminants like heavy metals, pathogens, and chemical residues, necessitating proper treatment and handling before use or disposal.

Uses of Organic Sludge

1. Fertilizer: When treated and processed correctly, organic sludge can be used as a nutrient-rich fertilizer.
2. Soil Conditioner: It improves soil structure, enhances water retention, and provides essential nutrients to plants.
3. Energy Production: Through anaerobic digestion, organic sludge can be used to produce biogas, a renewable energy source.

Treatment Methods

1. Anaerobic Digestion: Breaks down organic matter in the absence of oxygen, producing biogas and reducing sludge volume.
2. Composting: Aerobic decomposition of organic matter, resulting in nutrient-rich compost.
3. Thermal Treatment: Processes like incineration or pyrolysis to reduce volume and potentially recover energy.

Environmental Considerations

Proper management of organic sludge is crucial to prevent environmental pollution. Untreated or improperly managed sludge can lead to issues such as water contamination, soil degradation, and the spread of pathogens. Therefore, regulations and guidelines are in place in many regions to ensure safe and sustainable handling and disposal of organic sludge.

Source：ChatGPT

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: Organic sludge
• Purpose of drying: Reducing industrial waste cost and amount
• Moisture content: 84.8％W.B. before drying, 16.4％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

A fuel is any material that can be made to react with other substances so that it releases energy as thermal energy or to be used for work. The concept was originally applied solely to those materials capable of releasing chemical energy but has since also been applied to other sources of heat energy, such as nuclear energy (via nuclear fission and nuclear fusion).
The heat energy released by reactions of fuels can be converted into mechanical energy via a heat engine. Other times, the heat itself is valued for warmth, cooking, or industrial processes, as well as the illumination that accompanies combustion. Fuels are also used in the cells of organisms in a process known as cellular respiration, where organic molecules are oxidized to release usable energy. Hydrocarbons and related organic molecules are by far the most common source of fuel used by humans, but other substances, including radioactive metals, are also utilized.
Fuels are contrasted with other substances or devices storing potential energy, such as those that directly release electrical energy (such as batteries and capacitors) or mechanical energy (such as flywheels, springs, compressed air, or water in a reservoir).

Source：Wiki Fuel

Compost is a mixture of ingredients used as plant fertilizer and to improve soil’s physical, chemical, and biological properties. It is commonly prepared by decomposing plant and food waste, recycling organic materials, and manure. The resulting mixture is rich in plant nutrients and beneficial organisms, such as bacteria, protozoa, nematodes, and fungi. Compost improves soil fertility in gardens, landscaping, horticulture, urban agriculture, and organic farming, reducing dependency on commercial chemical fertilizers. The benefits of compost include providing nutrients to crops as fertilizer, acting as a soil conditioner, increasing the humus or humic acid contents of the soil, and introducing beneficial microbes that help to suppress pathogens in the soil and reduce soil-borne diseases.

Source：Wiki Compost

A fertilizer (American English) or fertiliser (British English) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Many sources of fertilizer exist, both natural and industrially produced. For most modern agricultural practices, fertilization focuses on three main macro nutrients: nitrogen (N), phosphorus (P), and potassium (K) with occasional addition of supplements like rock flour for micronutrients. Farmers apply these fertilizers in a variety of ways: through dry or pelletized or liquid application processes, using large agricultural equipment or hand-tool methods.

Source：Wiki Fertilizer

The three primary elements of fertilizer, essential for plant growth and commonly referred to as macronutrients in the context of plant nutrition, are:

Nitrogen (N):
Function: Promotes leaf and stem growth, as it is a crucial component of chlorophyll, the compound that plants use in photosynthesis to convert sunlight into energy. Nitrogen is also a key part of amino acids, the building blocks of proteins.
Deficiency Symptoms: Yellowing of leaves (chlorosis), stunted growth, and poor yield.

Phosphorus (P):
Function: Essential for energy transfer and storage in plants, as it is a component of ATP (adenosine triphosphate). Phosphorus also plays a vital role in root development, flowering, and seed production.
Deficiency Symptoms: Dark green or purplish leaves, delayed maturity, and poor root development.

Potassium (K):
Function: Regulates various metabolic activities in plants, including photosynthesis, protein synthesis, and water regulation. Potassium is also important for improving disease resistance and overall plant health.
Deficiency Symptoms: Leaf edges may turn yellow or brown (scorching), weak stems, and reduced resistance to drought and diseases.
Fertilizers are often labeled with an N-P-K ratio, which indicates the relative proportions of these three essential nutrients. For example, a fertilizer labeled as 10-20-10 contains 10% nitrogen, 20% phosphorus, and 10% potassium.

Source：ChatGPT

The shortage of lumber in Japan as of 2024 can be attributed to several factors:

1. Increased Demand: The global demand for lumber has surged due to a post-pandemic construction boom. As economies recover, the need for housing, infrastructure, and renovations has significantly increased, putting pressure on lumber supplies.

2. Supply Chain Disruptions: Ongoing disruptions in global supply chains, including transportation delays, port congestions, and logistical challenges, have made it difficult to import lumber into Japan efficiently.

3. Reduced Domestic Production: Japan’s domestic lumber production has been declining due to factors such as aging forestry workers, a lack of investment in modern forestry practices, and environmental regulations that limit logging activities.

4. Natural Disasters: Japan is prone to natural disasters such as earthquakes, typhoons, and floods, which can disrupt lumber production and supply chains, further exacerbating shortages.

5. Environmental Regulations: Stricter environmental regulations and sustainability practices have led to reduced logging activities in Japan and other countries, limiting the availability of lumber.

6. Geopolitical Tensions: Trade tensions and geopolitical issues with major lumber-producing countries can impact the availability and cost of imported lumber. Restrictions or tariffs on lumber exports from key suppliers can lead to shortages.

7. Economic Factors: Fluctuations in currency exchange rates, inflation, and the overall economic climate can affect the affordability and accessibility of imported lumber.

8. COVID-19 Impact: The lingering effects of the COVID-19 pandemic, including labor shortages and health-related restrictions, continue to impact production and transportation sectors globally, affecting lumber supply.

9. Forest Management Issues: Poor forest management practices and insufficient reforestation efforts in Japan have led to a depletion of local timber resources, contributing to the shortage.

These factors combined create a challenging environment for ensuring a steady supply of lumber in Japan, impacting various sectors that rely on this essential resource.

Source：ChatGPT

Biochar is a form of charcoal that is produced by heating organic material (biomass) such as wood, crop residues, or manure in a controlled environment with little or no oxygen through a process called pyrolysis. Here are some key aspects of biochar:

1. Production Process: Biochar is created through pyrolysis, which involves heating biomass in the absence of oxygen. This process thermally decomposes the organic material, producing a stable, carbon-rich product.

2. Soil Amendment: One of the primary uses of biochar is as a soil amendment. When added to soil, it can enhance soil fertility, improve water retention, increase microbial activity, and reduce the need for chemical fertilizers.

3. Carbon Sequestration: Biochar is highly stable and can remain in the soil for hundreds to thousands of years, effectively sequestering carbon and reducing greenhouse gas emissions. This makes it a valuable tool in mitigating climate change.

4. Environmental Benefits: Biochar can help reduce soil erosion, improve soil structure, and increase agricultural productivity. It also has the potential to filter and remove contaminants from soil and water, contributing to environmental remediation.

5. Energy Production: The pyrolysis process that produces biochar also generates syngas (a mixture of hydrogen, carbon monoxide, and other gases) and bio-oil, which can be used as renewable energy sources.

6. Waste Management: By converting agricultural and forestry residues, animal manure, and other organic waste into biochar, it provides a sustainable method of managing waste materials.

7. Livestock and Composting: Biochar can be used in animal husbandry to improve feed efficiency and reduce methane emissions from livestock. It is also used in composting to enhance the composting process and reduce odors.

8. Water Purification: Due to its porous structure and high surface area, biochar can be used as a filtration medium to remove pollutants from water, including heavy metals, organic contaminants, and nutrients.

Overall, biochar represents a versatile and sustainable solution with multiple applications in agriculture, environmental management, and energy production, contributing to both soil health and climate change mitigation.

Source：ChatGPT

Bio-coke is an eco-friendly fuel source produced from biomass, which are organic materials like plants and animals. Unlike traditional coke, which is derived from coal, bio-coke is made from renewable resources and offers a more sustainable alternative.

Here’s a breakdown of bio-coke:

• Raw Materials: Bio-coke can be created from various forms of biomass, including:

  • Waste materials like used tea leaves, coffee grounds, fruit peels, and sawdust
  • Energy crops specifically grown for bio-fuel purposes

• Production Process: Biomass goes through a process called pyrolysis, which involves heating the material in the absence of oxygen. This process removes moisture and volatile compounds, leaving behind a solid carbonaceous material – bio-coke.

• Applications: Bio-coke is primarily used as a substitute for coal coke in industrial processes, particularly steelmaking. Steelmaking traditionally relies on coal coke as a source of carbon and heat. Bio-coke offers a more sustainable alternative by reducing dependence on fossil fuels and potentially lowering greenhouse gas emissions.

Benefits of Bio-Coke:

• Renewable Source: Bio-coke is derived from renewable biomass, unlike coal coke which is a finite resource.
• Reduced Emissions: Bio-coke production can potentially lower greenhouse gas emissions compared to traditional coke production.
• Waste Management: Bio-coke can utilize waste materials like used coffee grounds and sawdust, promoting waste management and diverting them from landfills.

Challenges of Bio-Coke:

• Production Scale: Bio-coke production is still under development, and large-scale production facilities are not yet widespread.
• Properties: Bio-coke may have slightly different properties compared to coal coke, potentially requiring adjustments in industrial processes.
• Cost: Currently, bio-coke production can be more expensive than traditional coke production.

Overall, bio-coke is a promising development in the pursuit of more sustainable industrial practices. As research and development progress, bio-coke has the potential to become a more viable and widely used alternative to coal coke.

Source：Gemini

Both biochar and bio-coke are products derived from organic materials, but they have some key differences:

Processing Temperature:

• Biochar: Produced at lower temperatures (typically around 300-700°C) through a process called pyrolysis. Limited oxygen is present during pyrolysis.
• Bio-coke: Produced at higher temperatures (around 700-1000°C) in an almost complete absence of oxygen. This higher temperature process is more similar to coal coking.

End Product:

• Biochar: A porous and lightweight material with a high surface area. It’s rich in carbon but can also retain some nutrients from the original biomass.
• Bio-coke: Denser and has a higher carbon content compared to biochar. It shares some similarities with traditional coke in terms of physical properties.

Applications:

• Biochar: Primarily used for soil amendment. Its porous structure helps retain water and nutrients, improving soil health. It can also be used for filtration, as a source of renewable energy, and for capturing pollutants.
• Bio-coke: Intended as a sustainable substitute for coal coke in industrial processes, particularly steelmaking. It provides carbon and heat, similar to coal coke, but with potentially lower greenhouse gas emissions.

Here’s a table summarizing the key differences:

Feature	Biochar	Bio-coke
Processing Temperature	Lower (300-700°C)	Higher (700-1000°C)
Oxygen Presence	Limited	Almost absent
End Product	Porous, lightweight	Dense, high carbon
Applications	Soil amendment, filtration	Industrial fuel (steel)

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