Sludge is a by-product of wastewater treatment, it comes from various industries such as municipal wastewater treatment plants, paper manufacturing, chemical processing, electroplating. Sludge contains a lot of water and organic matter, and some types of sludge may also contain pathogens and heavy metals. Therefore, sludge needs to be processed properly to prevent environmental pollution. Also, sludge may also contain valuable resources that can be further used after treatment and recycling.

Currently, a commonly used sludge treatment method is the drying process, it achieves sludge resource utilization through sewage concentration, sludge dewatering, and sludge drying.

Process of sludge drying

1. Sludge thickening

Add flocculant to the sewage to form larger flocs from fine particles. Later, use a belt thickener or rotary thickener to allow water to seep out through mechanical compression and get high-concentration sludge.

2. Sludge dewatering

Sludge with a moisture content of 85%-90% is fed into a sludge dewatering machine (belt filter press or plate and frame filter press), through mechanical extrusion, a filter cake with a moisture content of 60%-70% is produced.

3. Sludge drying

Rotary drum dryer is the most common sludge dryer, it has a simple structure and high efficiency, suitable for large-scale industrial sludge treatment. The dewatered filter cake enters the drum, forms a thin, uniform, and complete material curtain under the combined action of the lifting plate and the drum. This curtain comes into full contact with the hot airflow, achieving the purpose of drying. After drying, the moisture content of the sludge reaches below 15%.

Resource utilization for dried sludge

1. As fuel

The calorific value of dried sludge is high. The calorific value of each ton of dried sludge with a moisture content of 20% is approximately equivalent to 0.3 to 1.2 tons of coal. It can replace coal or biomass fuel as energy supply in power plants, cement kilns, and industrial kilns.

2. Building materials

Some sludge contains silicon, aluminum, calcium, iron, and other mineral components. After dried, it can be used to make bricks, ceramsite, and cement clinker auxiliary materials to improve the performance of building materials.

3. Making fertilizer

Some sludge contains nutrients such as nitrogen, phosphorus, and potassium. After drying and disinfection, it can be used as organic fertilizers raw material to improve soil properties.

4. Landfill

For sludge that cannot be recycled, it can be dried and then directly landfilled as a stable solid. The volume of dried sludge in landfills is reduced by 70%-80%, making it safer.

Malaysia sludge drying for organic fertilizer project

The sludge in this project comes from a local palm oil factory. Malaysia has a large amount of palm crops, and palm oil factories generate lots of palm oil sludge every day. This kind of sludge is rich in natural organic matter and fiber, is a good raw material for organic fertilizer. Zhengzhou Jiutian customized a palm oil sludge drying solution for Malaysia customers, it can dry 10 tons of wet sludge per hour, reduce the sludge moisture content from 80% to 15%. High-temperature drying not only reduces moisture content but also effectively kills pathogens and insect eggs in sludge, making it suitable for use as an organic fertilizer additive and improving the stability of fertilizer formulations.

Conclusion

Sludge drying is an important link in sludge resource utilization. By reducing its moisture content and volume, and through high-temperature sterilization, it has been applied in fields such as fuel, construction, and fertilizer, and waste sludge can also be turned into treasure. If you are interested in our sludge treatment solutions, please feel free to inquire and get more information.