■What are the main types of dewatering machines? 1. Belt press: Sludge is sandwiched between two filter cloths and squeezed by rollers. 2. Screw press: Sludge is pushed into a narrow space and squeezed by a slowly rotating screw. 3. Centrifuge: Sludge is separated by being pressed against the inner wall of the outer cylinder by centrifugal force from high-speed rotation. 4. Filter press: Sludge is squeezed through filter cloths and operated in batches. 5. Vacuum dewatering machine: Sludge is suctioned and filtered through a rotating cylindrical filter cloth. ■How does the moisture content of the finished product differ? Generally, filter presses have a lower moisture content compared to other methods, with belt presses following closely. Centrifuges tend to have a higher moisture content in sludge with a high organic matter content due to the difference in specific gravity between solids and water. Vacuum dewatering machines tend to have higher moisture content because the pressure difference applied is smaller. ■Why is a coagulant added before dewatering? By creating strong flocs with a coagulant, fine particles become less likely to slip through, and the filter cloth is less likely to clog. As a result, this leads to a reduction in moisture content. Organic sludge often has a negatively charged surface that repels itself, so cationic coagulants are frequently used to neutralize the charge.

■What items should be compared when evaluating models? When comparing dewatering machines, the following items are considered: 1. Dewatering rate and SS recovery rate 2. Equipment cost and operating cost 3. Installation area 4. Ease of maintenance and working environment Centrifugal dewatering machines are widely used in wastewater treatment in food factories because they take up little space and help maintain a hygienic environment. ■The choice of chemicals varies by model! Centrifugal dewatering machines apply strong forces generated by rotation to the floc. Therefore, it is necessary to select polymer coagulants that can create robust flocs and ensure a high SS recovery rate. ■In the case of screw presses Screw presses have relatively large holes in the outer cylinder, so selecting chemicals that create strong flocs and the right reaction conditions is important. ■Should coagulants be determined through testing? In filter presses, the selection of filter cloth, pressure and time of pressing, and combinations of coagulants are determined through testing. To achieve effective dewatering, it is necessary to test several types of coagulants and understand the optimal combinations of dosage and pH. We can also provide advice on selecting coagulants tailored to the properties of the sludge and the dewatering machine. Please feel free to consult with us first.