Technological Characteristics of Screw Type Sludge Dehydrator

All the sludge dewatering machines have their own advantages and show their value in their particular field. The screw type sludge dehydrator has many advantages of low operating cost, high automation, easy to operate during sewage treatment

In the 1960s, screw type sludge dehydrator earliest appeared in Germany, which firstly used in pressing oil, leather processing, squeezing and dewatering ground meat and filtration of the waste. On the basis of more and more widely used, and for the reason that screw type sludge dehydrator have characteristics of separating mud the water easily, non-clogged and simple operation, it’s getting more widely used to dewater wastewater sludge of municipal, industrial, petrochemical, pharmaceutical, printing, metallurgy, food, aquaculture and so on .

Dewatering principle

The sludge will transfer along the direction of output of mud cake. The pitches of screw shaft decreased gradually, also the tiny spacing between moveable annular plates and fixed annular plates become more and more narrow, which makes the space of the cavity shrinking. Under the effect of the back-platen clogging, great pressure has been increased continuously. And finally, the purpose of fully dewatering will be achieved by the process of screw rotating orderly and continuously.

Key points of dehydration process

When customers order devices, they often hope for low price, while large and effective capacity. There are many skills that how to make full use of the dehydrator’s processing capacity to achieve the goal of good dehydration effect. Many of people who know screw type sludge dehydrator regard it has not much technical content.  But actually, it’s not truth.

The main factor affects the screw dehydrator’s processing result is flocculation effect. And flocculation effect is related to the operator’s understanding to sludge properties, such as the amount of the organic, inorganic substance, ss content, which kind of PAM should be chosen, if it is necessary to change the wastewater PH, add other flocculants and so on. What’s more, operator should adjust equipment according to sewage treatment requirements. For example, he should adjust the inlet -mud quantity according to the consistency of wastewater; he should adjust the gap of back-platen and the speed of driving motor according to dewatering effect, mud running situation and so on.

We should not only understand the principle of the equipment, but also should have a full understanding of sludge which need to be treated.

In spite of the same sewage and the same equipment, just different operation will make great different results. 

Screw dehydrator flocculation effect

There a considerable technical content that what kind of flocculation effect suit for screw dehydrator. Do not start the machine if the flocculation is not good, for the quantity of outlet mud cake will be small and with a high water content. Also, the spilled water between the moveable annual plate and fix annual plate will be very turbid. So firstly, we would request our customer to provide sewage sample for an experiment and then analyze the sewage properties to match the right flocculants.

A good flocculation in the experiment is not enough. We still need to use our hand-crossed fingers to simulate the device, which are similar to fixed annual plates and movable annual plates. The main purpose of this is to judge whether the floc filtered by crossed fingers will generate a good floc ball or not.

The sludge treatment requirement is not achieved if the floc remains sticking but not becomes to a ball. The better the effect of flocculation, the better the anti-pressure effect of sludge in the screw body chamber, the lower the water content of the sludge, the less sludge the machine runs, and the clearer the effluent is.

In the process of sludge treatment of screw press dehydrator, almost no rules are invariable and can be adjusted according to the specific conditions to achieve the best state and effect. Customers’ requirements for the operation of machines is simple and direct, that is, to maximize the profits by making the best results at a the lowest possible cost which is also our consideration in developing products.