Application of Decanter Centrifuge in Wastewater Treatment

With the rapid development of industrial production, population is concentrated in cities. A large amount of industrial and domestic wastewater is discharged into rivers, exceeding the natural purification capacity. Environmental pollution has become a very prominent social problem, seriously threatening the safety of people's lives. Therefore, wastewater treatment has attracted widespread attention.

Wastewater treatment is generally divided into three stages. Level 1: Natural settlement, removing heavy phase substances; Level 2: Biological and chemical treatment, adding biological bacteria or chemicals to wastewater to make harmful components harmless; Level 3: Physical and chemical treatment, perform deep processing on the basis of the first two levels.

After tertiary treatment, the water quality can meet discharge and even drinking standards. In the three-stage treatment, a large amount of sediment (sludge) appears in each stage. Some of the sludge can be recycled, but others will pollute the environment. Its moisture content is generally above 90%, and it needs to be dehydrated to reduce the moisture content to around 60%-80% before transportation and utilization.

For sludge used for soil improvement, high-temperature and biochemical treatment are also required to prevent the spread of bacteria and viruses in the sludge, which will harm the growth of plants and animals. After high-temperature and biochemical treatment, the sludge with a moisture content of over 95% also needs to be dehydrated.

Sludge dewatering is an important part of wastewater treatment, which has great significance in terms of economic value and prevention of environmental pollution. In recent years, decanter centrifuge is increasingly being used for sludge dewatering.

Decanter centrifuge is composed of two high-speed rotating rotors. One is a drum, the other is a screw, there is a differential speed between them. The drum is horizontally installed between two bearings, one end is connected with the belt pulley, driven by the electric motor. The other end is connected with the differential mechanism.

When the slurry water with a certain concentration is fed into the decanter, it will be separated by the centrifugal force. The solid phase will deposit on the drum wall, and be discharged through the discharge holes on the conical section of the drum. The liquid phase will form a liquid layer inside the drum, when the liquid exceeds the overflow holes on the cylindrical section of the drum, the liquid phase will be discharged through the overflow holes. Therefore, the solid phase and liquid phase will be separated. The discharge directions of solid phase and liquid phase are opposite, so this kind of machine is called countercurrent decanter centrifuge. It is widely used in many industries.

Decanter centrifuge has been used for sludge dewatering more than 30 years. Compared with other types of sludge dewatering machines, it has such advantages:

1. Compact structure and small footprint.

2. Less accessory equipment and lower equipment cost.

3. Sealed working conditions, low odor.

4. Especially suitable to treat sludge containing a large amount of fine particles.

5. Automatic, continuous and long-term operation.

6. No need to clean or replace filter cloth or mesh.

7. Easy operation and simple maintenance.

Because of this, decanter centrifuge is widely used in food, paper, pharmaceutical, chemical, environmental protection and other industries.