Condensation process of sludge / Sludge drying, Recycling drying

Sludge generated in wastewater treatment plants are treated by a wastewater treatment process called condensation to increase its density as a first step. Density of sludge whose ratio of solid content is less 1% or less is increased up to 4% maximum.
There are mainly two types of the condensation processes which are gravity type and mechanical type, and there are mainly 4 types in the mechanical type. Normally, wastewater treatment process after condensation is dehydration. However, recently some other processes are also used, such as process to increase solid content ratio of sludge by skipping condensation process and starting from dehydration which is post process of condensation, or process using equipment which can manage both condensation and dehydration.

Condensation process of sludge

Gravity type condensation

Sludge is condensed by spontaneous sedimentation in tanks.

Machine driving type


Centrifugal thickening

This is a method to condense sludge with centrifugal force. This device is configured by cylindrical screen outside and screw conveyer inside, and both of them are rotating. While screen outside and screw conveyer rotate opposite way, sludge are moved to outlet as being scraped off.

Dissolved air flotation thickening

Air is injected into pressure tank and it is added to dissolved air flotation tank where sludge is collected. Inside of the tank is in atmospheric pressure, therefore pressure is reduced and tiny bubbles are generated. The tiny bubbles are attached onto particles and the particles are floated up. Because of the bubbles being attached to sludge particles, they become lighter than water and float up. In this way, water and sludge are separated.

Atmospheric pressure flotation thickening

With mixing apparatus, bubbles generated by bubbling device and sludge are mixed. The mixture is moved to flotation tank and polymer flocculant is added to be adsorbed there. Sludge becomes lighter than water and float up with these steps. In this way, water and sludge are separated.

Belt type filtration thickening

This is a thickening device developed recently due to demand for cost reduction and energy saving. Thickening is done by adding polymer flocculant to sludge and supplying them onto filtration belt.



condensation wastewater treatment sludge dryer kenki dryer 24/05/2020



Types of waste water treatment / sludge drying, slurry drying, waste drying


■ Sludge drying


Water in the sludge thickened in the sludge thickener tank are removed at dehydration process to a certain degree.
However, moisture content is normally more than 80% and the sludge still has adhesiveness and stickiness. Also, latter processes are not easy because of influence of flocculants. Our drying apparatus of KENKI DRYER with international patented technology can surely dry any sticky, adhesive and viscus sludge, and also materials in liquid state like slurry, without clogging inside of the dryer. Also, because of its simple structure, its price is low and apparatus cost of the dryer can be retrieved by reducing industrial waste disposal cost within 3 years. Dried materials can be recycled as fuel, bacterial fertilizer, soil conditioner, etc. since component of the material is hardly changed because of its low-temperature drying method.
It can be applied to a system with pyrolysis apparatus as well.


Sludge drying



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.


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