What Is Mechanical Dewatering?

This process is associated with large wastewater treatment facilities. The primary method is to separate the sludge into solid and liquid parts using centrifuges, chamber filter presses, and belt filter presses. These systems are highly sophisticated and use some steps to dewater sludge. However, despite their sophistication, these methods do not completely treat sludge, which remains contaminated with pathogens and pollutants.


Process of removing water from sludge

Dewatering is a technique used to separate sludge into its solid and liquid components. It is used to remove water and treat the liquid part before it can be discharged or applied to land. For its disposal, sludge can be composted or burned. The mechanical dewatering processes include mechanical filtration, centrifugal separation, and centrifugal settling. However, unlike dewatering in neighborhoods, mechanical separation cannot work in the event of a power outage.

Different types of sludge exhibit different levels of dewaterability. WAS and primary sludge have different degrees of dewaterability. The amount of free water in both types of sludge can be determined using TGA analysis. THP-treated sludge is easier to dewater than regular sludge. After dewatering, THP plants have a greater cake solids percentage than traditional plants. The C/N-ash ratio is a good predictor of digestate type.


Methods of mechanical dewatering

Usually associated with large wastewater treatment plants, mechanical dewatering is separating sludge into its solid and liquid components. The most common dewatering methods use chamber filter presses, centrifuges, and belt filter presses. These dewatering processes are often complicated and require the use of chemicals. However, the result is a smaller volume of sludge that is easier to handle, transport, and dispose of.

These methods can be complemented by using a vacuum or RF field. Surfactants can also increase the efficiency of mechanical dewatering by reducing surface tension and capillary forces. Surfactants may also reduce the amount of moisture in the sludge by promoting hydrophobization of the solid surface.


Cost-effectiveness of mechanical dewatering

The economics of mechanical dewatering has long been controversial, but recent research has made progress possible. In 2009, the American Crystal Sugar Company started a research program to identify mechanical dewatering technologies. It provided a sugar beet sludge sample and a PulverDryer USA pulp sample. As a result, the AURI Drying Initiative has helped determine that mechanical dewatering has the potential to increase yields while minimizing energy consumption.

Using mechanical dewatering can reduce the capital and operating costs of wastewater treatment. The resulting sludge can be handled more easily and transported, incinerated or composted, or disposed of in landfills. In addition to reducing capital costs, mechanical dewatering can address various environmental issues, including pH, TSS, BOD, and COD. In addition, the volume of dewatered wastewater is reduced by three-fourths.


Application of mechanical dewatering equipment

The most effective dewatering equipment depends on the site’s conditions, available area, and budget. Generally, the dewatered solids’ residual moisture and centrate quality determine the disposal costs and pollution load returned to the treatment facility. Mechanical dewatering equipment reduces these parameters and helps in the minimization of both costs and pollution load. These systems are also efficient, require little maintenance, and do not require complex technical knowledge to operate. Besides, they can be upgraded to enhance productivity and efficiency.