In the current era of increasingly strict environmental protection supervision, sludge treatment has become a key link in the field of sewage treatment. Plate and frame filter presses, as commonly used sludge dewatering equipment, are widely applied in the sludge treatment industry due to their high solid-liquid separation efficiency and adaptability. However, when it comes to various types of sludge with complex compositions and high dewatering difficulty, the performance of plate and frame filter presses is often limited. The emergence of sludge efficiency enhancers has injected new vitality into plate and frame filter presses. The organic combination of the two has opened a brand-new chapter in efficient sludge dewatering.
I. Sludge Dewatering Dilemma and Limitations of Plate and Frame Filter Press
Municipal sludge and industrial sludge have complex compositions, containing a large amount of organic matter, microorganisms, heavy metals and colloidal substances, etc. These substances endow the sludge with the characteristics of high moisture content, high viscosity and high specific resistance. The water is closely combined with the sludge particles, and it is difficult to achieve effective separation by conventional methods. Although the plate and frame filter press achieves solid-liquid separation through mechanical pressure, there are many problems when dealing with such complex sludge. On the one hand, sludge is difficult to form structurally stable and large-sized flocs rapidly, resulting in a slow filtration rate and a long pressure filtration cycle. On the other hand, highly viscous sludge is prone to clogging the filter cloth, which not only reduces the filtration efficiency but also increases the frequency of filter cloth cleaning and replacement, raising the maintenance cost of the equipment. In addition, the moisture content of the dewatered mud cake is relatively high, which cannot meet the requirements of subsequent disposal and resource utilization, making it difficult for the plate and frame filter press to fully leverage its advantages in the deep dewatering of sludge.
Ii. The Principle of Synergistic Action between Sludge Enhancers and Plate and Frame Filter Presses
Sludge enhancer is a compound chemical agent specially developed to improve the dewatering performance of sludge. When used in combination with plate and frame filter presses, these components exert a synergistic effect to facilitate efficient dewatering of sludge.
When the sludge with added sludge enhancer enters the plate and frame filter press, the high-quality flocs formed after pretreatment are squeezed in the filter chamber. Due to the stable structure of the flocs, they are not easily broken under high pressure, effectively preventing sludge particles from passing through the filter cloth while allowing water to pass smoothly, thus achieving efficient solid-liquid separation. The mechanical pressure provided by the plate and frame filter press, in combination with the effect of the sludge enhancer in improving the sludge dewatering performance, significantly enhances the sludge dewatering effect.
Iii. The significant advantages of applying sludge enhancers to plate and frame filter presses
(1) Deep dehydration, efficient volume reduction
The combination of sludge enhancer and plate and frame filter press can significantly reduce the moisture content of sludge. For municipal sludge, the moisture content can be reduced from over 90% to 50% - 60%. The moisture content of industrial sludge can also be reduced from about 95% to 40% - 50%. After dewatering, the volume of the sludge cake is significantly reduced. Compared with traditional treatment methods, the sludge reduction effect can reach 60% - 70%, which greatly reduces the subsequent transportation and disposal costs of sludge and alleviates environmental pressure.
(2) Enhance filtration efficiency and shorten the pressure filtration cycle
The sludge treated with the sludge enhancer forms flocs with a good structure and its filtration performance is significantly improved. During the operation of the plate and frame filter press, the filtration speed is significantly increased and the filtration cycle is greatly shortened. Previously, it might take 4 to 6 hours to process a batch of sludge. However, after adding sludge enhancers, the processing time can be shortened to 1 to 2 hours, and the production efficiency of the equipment has increased several times. More sludge can be processed within a unit of time, meeting the large-scale sludge treatment needs of enterprises.
(3) Reduce filter cloth clogging and lower maintenance costs
The sludge enhancer improves the viscosity and particle structure of the sludge, reducing the adhesion and clogging of the sludge on the surface of the filter cloth. The cleaning frequency of the filter cloth has been reduced from several times a day to several times a week. The service life of the filter cloth has also been extended, and the replacement cycle has been prolonged from several months to 1-2 years. This not only reduces the procurement cost of filter cloth, but also lowers the workload of equipment maintenance and downtime, ensuring the stable operation of the plate and frame filter press.
(4) Wide adaptability and strong applicability
The sludge enhancer can be formulated and adjusted according to the characteristics of different types of sludge. Whether it is municipal sludge, papermaking sludge, leather sludge, printing and dyeing sludge, chemical sludge, etc., it can be well adapted to the plate and frame filter press. Enterprises do not need to carry out large-scale renovations on the existing plate and frame filter press equipment. They only need to adjust the dosage of the sludge enhancer and the reaction conditions to achieve efficient dewatering, which has strong universality and flexibility.
(V) Environmentally friendly and facilitating resource utilization
The use of sludge enhancers does not introduce new toxic and harmful substances, and can effectively reduce the mobility of heavy metals and the content of organic pollutants in sludge. The dehydrated mud cake is more in line with the requirements of subsequent resource utilization, such as being used to make building materials, soil conditioners, or for incineration power generation, etc., promoting the transformation of sludge from waste to resource and achieving a win-win situation of environmental and economic benefits.
Iv. Practical Application Cases
A certain municipal sewage treatment plant can treat 300,000 tons of sewage per day and generates a large amount of municipal sludge every day. The factory originally used plate and frame filter presses to directly treat sludge, which had problems such as a long filtration cycle (about 5 hours), high moisture content of the mud cake (about 75%), and frequent clogging of the filter cloth. After introducing the sludge enhancer, the optimal dosage was determined through laboratory beaker tests. After the sludge enhancer was thoroughly mixed and reacted with the sludge, it was then sent to the plate and frame filter press for treatment. The results show that the filtration cycle has been shortened to 1.5 hours, the moisture content of the mud cake has dropped to 55%, and the cleaning frequency of the filter cloth has decreased from three times a day to twice a week. The factory saves over one million yuan annually on filter cloth replacement costs and sludge disposal costs. At the same time, the sludge reduction effect is remarkable, laying a solid foundation for the subsequent resource utilization of sludge.
The printing and dyeing sludge produced by a certain printing and dyeing enterprise contains a large amount of dyes and sizing agents, and the dewatering is extremely difficult. After the combined treatment with the sludge enhancer and the plate and frame filter press, the moisture content of the sludge dropped from 93% to 48%, and the originally dark and sticky sludge was transformed into easily treatable mud cakes. The enterprise not only solved the problem of sludge treatment, but also used the dewatered sludge cakes to make environmentally friendly bricks, achieving the resource utilization of sludge and creating additional economic benefits.
V. Conclusion
The combination of sludge enhancers and plate and frame filter presses provides an innovative and effective solution for efficient sludge dewatering. The two complement each other's advantages and have achieved remarkable results in deep dehydration, improving efficiency, reducing costs and protecting the environment. With the continuous improvement of environmental protection requirements and the continuous development of sludge treatment technology, the application of sludge enhancers in plate and frame filter presses is expected to be further expanded and deepened, injecting strong impetus into the green and sustainable development of the sludge treatment industry and leading the industry to a higher level.