In the field of sludge treatment, sludge dewatering is a crucial step. It can significantly reduce the volume of sludge, facilitating subsequent transportation and disposal. During this process, various chemicals will be used. Among them, sludge enhancers and commonly used sludge dewatering chemicals on the market are of particular concern to people, and there are many differences between them.
Component differences
The commonly used sludge dewatering agents on the market, such as polyaluminium chloride (PAC) and aluminium sulfate in inorganic flocculants, are mainly some metal salt substances. These metal salts undergo hydrolysis and polymerization reactions in water, forming positively charged colloidal particles. By adsorbing the negatively charged particles in the sludge, they aggregate together, thereby achieving sludge dewatering. Sludge enhancers, on the other hand, are a type of compound agent, typically consisting of organic high-molecular polymers, surfactants, and some special additives. These components work together to improve the dewatering performance of sludge in multiple aspects. For instance, organic high-molecular polymers can act like "ropes", tightly binding sludge particles together to form larger flocs. Surfactants can reduce the surface tension between sludge particles and water, making it easier for water to separate from the sludge.
The effects are different.
After using commonly used sludge dewatering agents, although certain flocs can be formed in the sludge, the structure of these flocs is often relatively loose and their strength is insufficient. During the subsequent dewatering process, for instance, when using a plate and frame filter press for filtration, the flocs are prone to being squeezed and broken, resulting in insufficient water discharge and maintaining a relatively high moisture content in the sludge. Moreover, these agents have limited ability to capture some fine particles and colloidal substances in the sludge, and cannot completely coagulate these substances together, resulting in a considerable amount of water and impurities remaining in the sludge after dewatering.
Sludge enhancers can significantly improve these problems. The flocs it forms have a compact structure and high strength, and are not easily destroyed during the dewatering process. Take the sludge enhancer as an example. In the actual application of a certain sewage treatment plant, after using this sludge enhancer, the moisture content of the sludge cake pressed out by the plate and frame filter press was reduced from over 80% to about 60%, which greatly improved the dewatering efficiency of the sludge. Meanwhile, the sludge enhancer has a good capture and coagulation effect on various particles and colloidal substances in the sludge, which can make the water in the sludge separate more thoroughly. The dewatered sludge is drier and more convenient for subsequent treatment and utilization.
There are differences in environmental friendliness
Commonly used sludge dewatering agents, especially inorganic flocculants, may introduce some heavy metal ions, such as aluminum ions, during the application process. If these heavy metal ions are not properly treated, they will enter the environment along with sludge, causing pollution to soil and water bodies, and affecting the ecological environment and human health. Moreover, the dosage of these chemicals is usually large, which will also increase the cost of sludge treatment and its impact on the environment.
Sludge enhancers are relatively more environmentally friendly. It does not contain harmful substances such as heavy metals and will not cause secondary pollution to the environment during use. Meanwhile, due to its highly efficient dewatering performance, it can reduce the dosage of chemicals, lower the cost of sludge treatment, and meet the requirements of sustainable development.
Economic cost consideration
In the short term, the prices of commonly used sludge dewatering agents are relatively low and the purchase costs are not high. However, due to its limited dewatering effect, in order to achieve a better dewatering result, a larger dose of chemicals is often required. Moreover, the moisture content of the sludge after dewatering remains relatively high, and further treatment such as drying is still needed subsequently, which will increase additional treatment costs.
Although the unit price of sludge enhancers may be relatively high, due to their small dosage and good dewatering effect, they can significantly reduce the moisture content of sludge and lower the cost of subsequent treatment. In the long term, the use of sludge enhancers can reduce the total cost of the entire sludge treatment process and improve economic benefits.
To sum up, there are obvious differences between sludge enhancers and commonly used sludge dewatering agents on the market in terms of composition, effectiveness, environmental friendliness and economic cost. When choosing sludge dewatering agents, these factors should be comprehensively considered based on the actual situation to select the most suitable agent, so as to improve the efficiency and quality of sludge treatment and achieve a win-win situation of economic and environmental benefits.