What are the main methods of sludge treatment?

1, sludge concentration

Concentration is a common method of solid-liquid separation, which can be accomplished in two ways: the solid floats to the top of the mixed liquid or settles to the bottom of the mixed liquid. The former is generally called air flotation, while the latter is called gravity beneficiation. The purpose of sludge concentration is to separate excess water from sludge as much as possible before sludge digestion or dehydration.

Generally speaking, sludge concentration can effectively reduce the processing capacity required by subsequent units of sludge treatment such as digestion and dehydration, and the cost saved by subsequent units due to volume reduction is much higher than the setting and operation cost of sludge concentration unit, so setting sludge concentration unit is helpful to reduce the total cost of sludge treatment process. ?

2. Sludge treatment

chemical conditioning

The main purpose of sludge conditioning is to promote solid-liquid separation of sludge. Among the available technologies, the most common way is to add coagulant, such as ferric chloride, lime or organic polymer flocculant, and sludge incineration ash can also be used as sludge conditioner. Adding coagulants to turbid liquids such as sludge can promote the coagulation of solid substances and make them easier to separate from water.

In recent years, organic polymer flocculants have been widely used in sludge conditioning. Organic polymer flocculant is easy to handle, occupies a small volume, is simple to use and operate, and has a very good effect. Flocculants are usually injected into the sludge before dehydration and are fully mixed with the sludge. ?

3. Heat treatment

Another sludge conditioning method is to heat the sludge at high temperature (175~230℃) and high pressure (1000~2000kPa), and the bound water in the sludge solid is released, so the dewatering characteristics of the sludge can be improved. The advantage of heat treatment is that the dewatering effect of conditioned sludge is better than that of chemical conditioner; The disadvantage is that the operation and maintenance of the system are complicated, and at the same time, the sludge heat treatment will also produce high-concentration cooking liquid, which will obviously increase the load of the treatment unit when it flows back to the sewage treatment plant.

Extended data:

As a kind of solid waste, sludge has become the second largest source of solid waste pollution after municipal solid waste pollution. The traditional sludge disposal methods mainly include landfill, incineration, sea discharge, agriculture and so on. However, the traditional treatment methods also have some disadvantages, which can not realize the recycling of sludge and meet the current technical requirements of sludge treatment. Therefore, it is of great practical significance to study and develop new technologies for sludge treatment and recycling.

The treatment and disposal of sludge should be comprehensively considered from the aspects of environmental pollution, health and safety, and economic benefits. The new sludge treatment technology of energy recycling will play an irreplaceable role in sludge treatment and disposal.

With the strengthening of environmental protection and people's further understanding of the limitations of existing sludge treatment and disposal technologies, countries all over the world are investing heavily in the research and development of new technologies in order to find more economical and reasonable sludge treatment schemes.