What are the sludge dewatering technologies in domestic sewage treatment projects?

For domestic sewage treatment, attention should be paid not only to the treatment of pollutants in sewage, but also to the residual sludge after treatment. At present, in general domestic sewage treatment projects, sludge treatment mainly adopts these two dehydration technologies: domestic sewage treatment equipment.

1. Natural drying method. Its main structure is the sludge Qianhua field. The sludge is surrounded and separated by the dam, and the soil permeability is poor. A thin layer of gravel and sand can be paved, and concealed drainage pipes can be set. The water content of sludge discharged on site is reduced by infiltration method and evaporation method. The leakage is completed within 2-3 days to reduce sludge water, and then it is mainly realized by evaporation. The dewatering effect of sludge drying field is affected by local precipitation, evaporation, temperature, humidity and other factors. It is usually suitable for use in arid, little rain and sandy soil.

2. Mechanical dehydration method. Before dewatering, it is usually necessary to pretreat the sludge to improve the dewatering performance. Common pretreatment methods include adding inorganic salt or polymer coagulant, flocculant, etc. In addition, there are elutriation and heat treatment methods. Mechanical dehydration has two methods: filtration and centrifugation. The filter uses the filter layer to filter the sludge (such as filter cloth, metal mesh and other porous materials), infiltrate the water (filtrate) into the filter layer, and intercept the dewatered sludge (filter cake) on the filter layer. It realizes the separation of mud and water under the action of centrifugal force thousands of times larger than gravity with the help of different centrifugal tendencies caused by the difference of solid-liquid ratio in mud and water.

As mentioned above, mechanical dewatering is not affected by the weather, and has high dewatering efficiency and good effect. Therefore, it has become the main dewatering technology used in the field of sludge treatment.