Sludge dewatering is one of the key links in the municipal sewage treatment process. However, many sewage treatment plants are confronted with the problem of excessively high moisture content in sludge cakes, which not only increases the volume and weight of sludge but also raises the cost of subsequent treatment and disposal. This article will conduct an in-depth analysis of the reasons for the excessively high moisture content of mud cakes and recommend effective dewatering agents and sludge enhancers to help sewage treatment plants solve this problem.
Analysis of the Reasons for the excessively high moisture Content of mud cakes
The nature of sludge is complex
Municipal sludge contains a large amount of organic matter, colloidal substances and microbial cells. These components are closely bound to water and are difficult to remove by conventional dewatering methods. Especially colloidal substances and water within microbial cells are even more difficult to separate.
2. The performance of the dehydration equipment is insufficient
The performance of the dehydration equipment directly affects the dehydration effect. If the equipment parameters are not set properly, such as insufficient tension of the filter belt, inadequate pressure of the flushing water, or unreasonable setting of the dewatering machine's rotational speed or pressure, it will lead to low dewatering efficiency and an increase in the moisture content of the mud cake.
3. Improper selection of chemicals
The selection of dehydration agents is crucial to the dehydration effect. If the type of reagent does not match or the dosage is insufficient, it will be impossible to effectively destroy the colloidal structure in the sludge, reduce the viscosity of the sludge, and thereby improve the dewatering efficiency.
Recommendation of Dehydrating agents
Cationic polyacrylamide (PAM）
Cationic polyacrylamide is a highly efficient flocculant. It neutralizes the negative charges on the surface of sludge colloids through the adsorption bridging effect of molecular chains, forming flocs to accelerate solid-liquid separation. It is applicable to sludge dewatering in urban sewage treatment and industrial scenarios such as mines, sand yards, and construction pile driving. The ion degree range covers 30% to 60%, with a molecular weight of 16 to 25 million units. The dosage is usually 3 to 60 kilograms per thousand tons of wastewater.
2. Polyaluminium Chloride (PAC）
Polyaluminium chloride is an inorganic high-molecular coagulant that can hydrolyze to form aluminium hydroxide colloid, adsorb suspended particles and colloidal substances in sludge, and form larger flocs, which is convenient for subsequent dewatering treatment. It is often used in combination with cationic polyacrylamide to enhance the dehydration effect.
3. Lime
Lime, as a traditional sludge conditioner, can adjust the pH value of sludge, destroy the colloid structure and reduce the viscosity of sludge. However, a large amount of lime is used and it can cause corrosion to equipment, increasing operating costs. Therefore, careful consideration is needed when using it.
Recommendation of sludge enhancer
Sludge enhancer is a kind of chemical agent specifically used to improve the dewatering performance of sludge. It has the following core advantages:
Youdaoplaceholder0 Destroy colloid structure : Sludge enhancers can destroy the colloid structure in sludge, making it easier to separate and dewater sludge particles.
Youdaoplaceholder0 Reduce sludge viscosity : By reducing the viscosity of sludge, sludge enhancers can make it easier to remove water from sludge in equipment such as filter presses or centrifuges.
Youdaoplaceholder0 Increase the solid content of sludge : After using the sludge enhancer, the solid particles in the sludge are more likely to aggregate together, thereby increasing the solid content of the sludge and reducing the moisture content.
Youdaoplaceholder0 Reduce pretreatment steps : Sludge enhancers can improve the colloid structure and viscosity of sludge, simplify or omit some cumbersome pretreatment steps, such as long-term stirring and pH value adjustment.
Youdaoplaceholder0 Enhance dewatering efficiency : Sludge enhancer Sludge enhancer can significantly improve the dewatering efficiency of sludge, shorten the dewatering time, and reduce the operation time and energy consumption of dewatering equipment.
To solve the problem of sludge dewatering in municipal sewage treatment and reduce the moisture content of sludge cakes, it is necessary to start from multiple aspects such as the properties of sludge, the performance of dewatering equipment and the selection of chemicals. By rationally selecting and using dewatering agents and sludge enhancers, the dewatering efficiency of sludge can be significantly improved, the moisture content of sludge cakes can be reduced, and significant economic and environmental benefits can be brought to the operation of sewage treatment plants.