A sludge dewatering machine is a device that uses physical and mechanical methods to remove moisture from sludge, primarily for the volume reduction of sludge following wastewater treatment. The core process involves concentration, dewatering, and filter cloth cleaning, achieving water separation through stepwise pressurization. The main body is made of stainless steel and is equipped with a filtrate recovery system to facilitate resource recycling.

During the operation, sludge first mixes with a high molecular coagulant to form particles. After the concentration system screens out free water, the sludge enters the pleat gaps for gravity dewatering. The dewatering process is divided into two stages: the gravity stage and the pressurized stage. In the gravity stage, free water is filtered out by gravity. In the pressurized stage, the water is squeezed out through a spiral shaft that creates a gradient pressure, further reducing the moisture content of the sludge cake in the high-pressure shear zone. The filter cloth is cleaned using a self-cleaning mechanism that involves the relative motion of the stationary and moving rings, which helps prevent clogging issues common in traditional equipment. The sludge cake is finally removed by a scraper. The open design facilitates operation and monitoring, and the distribution device prevents side leakage during processing.

Adjust the mixing tank

The injected sludge and conditioner —— polymer coagulant (POLYMER) are mixed uniformly in the conditioning mixing tank, and the gel becomes solid particles (FLOC) easy to be dehydrated, and then flows to the front mud-water separation screen and concentration tank.

The conditioning tank is made of stainless steel, and the conditioning tank is installed on the machine with an open structure, so that the management personnel can easily observe the conditioning situation and the amount of polymer agglomeration agent used.

Concentrator system

After conditioning, the sludge is introduced into the fine screen of the screening and separation tank. Under the action of the centrifugal screening machine (rotational speed 30r.p.m., power 0.25KW/unit), a large amount of upper liquid (free water) is filtered out by slow rotation and tumbling, so as to achieve the function of sludge concentration and reduction, improve the processing capacity of the machine, and shorten the operation and treatment time.

After screening and separation, the sludge can significantly reduce the water permeability load on the filter cloth. At this point, the structure of the sludge is stable, with no overflow or side overflow, which enhances the efficiency of the subsequent roller pressing dewatering process and reduces the moisture content of the sludge cake. The solid content in the free water after screening and separation ranges from 0.5‰ to 1‰ (depending on the type and amount of POLYMER added).

Sludge distribution device

Sludge concentration distribution device: the sludge ball is distributed centrally on the filter cloth according to the standard, and the width of the sludge ball can be adjusted according to the spreading characteristics of the sludge when it is squeezed, so that the filter cloth and the sludge dewatering machine roller can bear uniform pressure, and prevent the occurrence of leakage.

Sludge dewatering section

Gravity dehydration

The sludge with low solid content after screening is evenly distributed on the filter belt running at a speed of 1~7m/min. With the running of the filter belt, most of the free water in it is gradually removed due to gravity. A small part of the water also passes through the tiny mesh holes on the filter cloth for free gravity dehydration.

Pressurized dehydration

The sludge clumps, after gravity dewatering, enter the filter belt through a concave throat. This process ensures that the sludge remains within the predetermined width of the filter belt and prevents leakage or thickening of the cake. The sludge then gradually passes through a series of rollers of fixed sizes, with the pressure applied to the sludge increasing progressively to achieve dewatering. After initial dewatering, the sludge enters a series of main and auxiliary rollers of fixed sizes, where the pressure applied to the sludge is gradually increased to achieve high-efficiency dewatering.

The sludge, after high-efficiency dewatering, is subjected to an appropriate pressure gradient in the high-pressure shear zone (where the pressure of the sludge is increased by the arrangement of rollers) to reduce the moisture content of the cake. The sludge is then forced out using a high-pressure shear zone (powered by air compressors, which can be adjusted according to operational needs), ensuring that the remaining moisture in the cake is completely and thoroughly removed, resulting in a cake with a lower moisture content.

Cloth cleaning device

Using nozzles evenly distributed on a closed device (which facilitates maintenance and cleaning, and prevents rinse water from splashing and wetting the mud cake), the cleaning water, pumped by a pump (with a maximum flow rate of 8M3/hr, a head of 45m, and a power of 2.2KW), is sprayed out as a water jet from the nozzles (with a cleaning water pressure of 4kg/cm2 and a total water demand of 7m3/hr) to spray the upper and lower filter cloths, creating a 65-degree fan-shaped spray that helps reduce water pressure loss;

The amount and speed of the spray water can be adjusted according to actual operational needs to thoroughly remove residual mud from between the filter cloth mesh holes. Additionally, water pressure cleaning helps maintain the filter cloth’s permeability, reduces the moisture content of the filter cake, extends the filter cloth’s lifespan, and prevents side leakage caused by severe clogging of the filter cloth in the QiLi Environmental Sludge Dewatering Machine. The cleaning system is equipped with a filter liquid retention and receiving device, which recovers and treats the filter liquid for reuse as rinse water.

Sludge cake unloading

There is a blade in close contact with the upper and lower filter cloth, and the purpose of removing sludge is achieved by adjusting the tightness of the spring.