What is sludge dewatering? The purpose of dewatering during sludge treatment is .

A variety of chemicals can be used for sludge deep dewatering, and the following are the most common chemicals used for ordinary sludge dewatering:

Cationic polyacrylamide: This is a polymer flocculant, which can flocculate small particles in sludge into larger particles through adsorption and bridging, and improve the sedimentation performance and dewatering performance of sludge.

Polyaluminum chloride: This is an inorganic polymer coagulant, which can coagulate with impurities in the sludge to form an insoluble precipitate, so that the water in the sludge is separated.

Lime: Lime can neutralize with the acids in the sludge, adjust the pH value of the sludge, and promote the cohesion and settlement of the sludge.

Diatomaceous earth: Diatomaceous earth has the characteristics of porosity and high specific surface area, which can be used as a filter aid to improve the filtration performance and dewatering performance of sludge.

It should be noted that different kinds of agents are suitable for different sludge properties and treatment requirements, so it is necessary to choose the appropriate agent according to the specific situation in practical applications. For sludge with high organic matter, under the condition that lime is not allowed to be added in the process, it is necessary to customize the organic deep sludge dewatering agent, and adjust the corresponding process parameters to ensure the sludge treatment effect.

A sludge treatment method that removes water from the flowed primary, thickened or digested sludge and converts it into semi-solid or solid sludge blocks. After dewatering, the moisture content of the sludge can be reduced to 55 to 80 percent, depending on the nature of the sludge and sediment and the efficiency of the dewatering equipment. Further dewatering of the sludge is called sludge drying, and the moisture content of the dried sludge is less than 10%.

The main methods of dehydration are natural drying method, mechanical dehydration method and granulation method. Natural drying and mechanical dewatering are suitable for sewage sludge. The granulation method is suitable for coagulation and sedimentation sludge.

The encyclopedia has it.,It's quite detailed.。

Sludge is a solid-liquid mixture formed by bacteria, fungi, living cells and their formed colloids and water, and the reason why it is difficult to dehydrate is in the composition of water. It is generally believed that there are about four forms of binding of water:

1) Interstitial water (free water).

The interstitial water, which is surrounded by large and small sludge, does not bind directly to the solids and separates by gravity. This part of the water accounts for about 70% of the total water.

2) Capillary water.

The water around the highly dense fine sludge solid particles, due to the capillary phenomenon, constitutes the following types of water: wedge-shaped capillary bound water, which is combined into wedge-shaped capillary water due to the action of capillary pressure on the contact surface of the particles; Interstitial capillary binding water, capillary water that fills the space between solids and solids; fissure capillary bound water; Capillary water filled with the cracks in the solid itself. To remove the bound water under capillary pressure, it is necessary to apply a force opposite to the resultant force of the capillary surface tension.

Centrifugal force (centrifuge), negative pressure (vacuum filter), electroosmotic force or thermal permeability, etc. This part of the water accounts for about 20% of the total water.

3) Adsorption of water.

It is tightly adsorbed with the solid by molecular force, and cannot be removed by centrifugation or other mechanical forces.

4) Internal water.

Interstitial water, capillary bound water, surface adsorption water are all external liquids, a part of the sludge water is surrounded in the cell membrane of microorganisms, such as cell sap, this internal water is very tightly bound to the solid, to remove this water, the cell membrane must be destroyed, through biodegradation (aerobic oxidation, composting, anaerobic oxidation), or the use of high temperature and freezing measures.

That is to say, the first two are easy to remove by mechanical force, and the latter two are difficult, resulting in difficult sludge dewatering and high energy consumption.

As long as you choose the right type of flocculant, it is recommended to choose medium and high ionic cationic polyacrylamide, and the content of municipal sludge is more complex.

Nico Environmental Technology**** Sludge Non-thermal Drying NHD Technology, using non-heating method to dewater and dry sludge, it only takes 10 minutes to reduce the moisture content of sludge from 85%-80% to 55%, and then through the forced ventilation drying technology in the non-heated state, the moisture content in the sludge continues to reduce to 40%, and the energy consumption is only 10% of thermal drying, and the treatment process will not produce odor.

Sludge heatless drying NHD technology "overcomes the worldwide problem of high energy consumption and odor generation of sludge drying." Another striking result is that the dried mud cake has a fairly high calorific value.

Due to the drying process without heating, the loss of organic matter in the sludge is avoided. The biomass fuel made from the dried mud cake has been tested by the authoritative department, and the actual detection effect of the sludge heatless drying project of the MCC Sewage Treatment Plant in Funing District, Qinhuangdao is taken as an example, and the calorific value reaches 4080 kcal, which is higher than that of lignite, and the mud is truly turned into "coal". It realizes the principle of circular economy advocated by the state, and truly realizes the reuse of resources for sludge treatment and disposal.

Answer]: The moisture content of the sludge is very high, and it needs to be thickened before sludge treatment to reduce the moisture content of its source to reduce the volume of treatment equipment and treatment cost. Sludge dewatering is a sludge treatment method that removes water from the fluidized primary, concentrated or digested sludge and converts it into semi-solid or solid sludge blocks.

Sludge dewatering is done to reduce the volume of sludge for easy transportation, storage and disposal. The dewatering performance of sludge is related to the nature of sludge, conditioning methods and conditions, etc., and is also related to the type of dewatering machinery.