Low-temperature drying of organic sludge for upcycling / Test cases / Sludge drying, Sludge dryer

Summary

KENKI DRYER is a specialized low-temperature dryer designed to process sludge from wastewater treatment plants, maintaining the composition of the dried material for potential upcycling. This technology supports Japan’s need to recycle precious and minor metals, such as phosphorus, which is largely imported from China. Reusing and recycling sludge aids in environmental protection, reduces greenhouse gases, and lessens dependence on imported minerals.

KENKI DRYER excels in drying sticky, high-moisture sludge without clogging, a common issue with other dryers. It operates as an indirect steam dryer with high heat efficiency, using excess steam and potentially an electric boiler to minimize carbon dioxide emissions, enabling decarbonized drying.

This continuous, unmanned dryer can operate 24/7, aiding in waste weight reduction and decreasing transportation costs and carbon emissions. With 11 international patents, the KENKI DRYER is recommended for various high-moisture organic waste and sludge drying applications.

KENKI DRYER dries sludge discharged from wastewater treatment plants at low temperatures so that the composition of the dried material changes little after drying and can be used as an upcycled product. It is possible to recycle and upcycle products.

Japan is almost 100% dependent on imports for its mineral resources. In particular, precious and minor metals will continue to be important resources in the future, and it is essential to secure these resources in order to maintain and strengthen international competitiveness. The reuse and recycling of the minerals contained in sludge is an important measure to secure mineral resources, which contributes to environmental protection and reduces greenhouse gases. Phosphorus, which is currently imported from China, is also an essential mineral. The extraction of phosphorus from sewage sludge is therefore being promoted as a national project.
The reuse and recycling of sludge from wastewater treatment plants is of great importance for environmental protection, decarbonization and securing resources that are currently dependent on imports and the demand for which is only increasing.

Even very sticky and difficult to handle materials with high moisture content can be dried easily and smoothly with the KENKI DRYER. For example, sludge with high adhesion and stickiness is difficult to dry, and with some other types of dryers, sludge may clog the dryer during drying and not be discharged. The KENKI DRYER has a unique mechanism, patented worldwide, that allows smooth drying without clogging the dryer, no matter how sticky or sticky the sludge is.

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 because of its high drying heat efficiency, the amount of steam used can be reduced. The use of excess steam means no fuel costs and no carbon dioxide emissions from the dryer during the drying process, allowing for decarbonized drying. Alternatively, by installing an electric boiler, no greenhouse gases or carbon dioxide CO2 are emitted during the drying process.

KENKI DRYER is a continuous dryer, not a batch dryer, which stores and dries the material to be dried. This makes it easy to manage and allows unmanned operation 24 hours a day.

Drying sludge to reduce its weight and the amount of waste material can contribute to environmental protection and decarbonization by reducing the cost of industrial waste, which has been rising recently due to the 2024 truck problem, and by reducing the number of trucks used to transport the waste, carbon dioxide emissions can also be reduced.

KENKI DRYER is a revolutionary drying system with a total of 11 patents, 2 in Japan and 9 in 7 foreign countries. Please consider the KENKI DRYER for high water content organic waste dryers, sludge dryers, slurry dryers, methane fermentation digested liquid dryers and waste recycling dryers.
KENKI DRYER has been granted 11 patents in 8 countries (Japan, Taiwan, USA, France, Germany, UK, Switzerland and Canada).

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

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

• Material to be dry: Organic sludge
• Purpose of drying: Upcycling, Reducing industrial waste cost and amount
• Moisture content: 83.2％W.B. before drying, 12.8％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

Competitive comparison

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