Sludge dewatering expert -- German Andritz diaphragm chamber filter press

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Experts in sludge dewatering – Andritz diaphragm filter presses from Germany. Author: PROCESS «Process Industry». In the field of sludge dewatering, the equipment commonly used includes diaphragm filter presses, centrifuges, and belt filter presses. Compared to centrifuges and belt filter presses, diaphragm box filter presses have distinct characteristics. Diaphragm box filter presses are not affected by the properties of the sludge; they produce filter cakes with a high solid content, and their operating and maintenance costs are low. Therefore, diaphragm chamber filter presses are not only used in municipal water supply and sewage treatment plants, but also find wide application in industries such as chemicals, biology, pharmaceuticals, mining, coal, metallurgy, and food. Their excellent performance has earned them the reputation of being \"experts in sludge dewatering\". Technical features of diaphragm chamber filter presses: The design filtration pressures for conventional filter presses are typically 0.8 MPa and 1.6 MPa, while the maximum design filtration pressure available today can reach 6.0 MPa. The diaphragm pressing pressure is 1.6 MPa, while filter presses with a pressing pressure of 3.0 MPa are also beginning to be widely used. Due to the increased pressure, in most applications the solid content of the filter cake is significantly higher compared to other separation devices. Over the course of its development, the filter plates used in filter presses have a minimum size of 250mm×250mm, while the maximum size can reach 2450mm×2450mm. The filtering area of a single filter press can go up to 2000 m2. The structure of diaphragm box filter presses usually includes a cantilever design and a side bar design. Among them, the beam-type filter press features an open design, which allows free access to the open filter plate assembly when the press is opened, enabling individual maintenance of each filter plate. The side-bar type and beam-type filter presses operate in a batch-based cyclic process, which includes: feeding — filtering — pre-pressing (optional) — central backwashing — filter cake washing (optional) — post-pressing — filter cake purging (optional) — cake discharge, as well as filter cloth cleaning (with adjustable frequency). Initially, filter presses used manual plate pulling, which involved high labor intensity and harsh working conditions. Thanks to years of technological advancements, filter presses now mostly feature a fully automatic plate-pulling design. The pull plate mechanism design for Andritz filter presses is at the forefront of the world; it includes a single-plate movement (single pawl) design, a multi-plate coordinated movement (multiple pawls) design, as well as a continuous cyclic chain-driven pull plate design unique to beam-type filter presses, which enables continuous cake discharge. These pull plate designs are widely used in the chemical, coal, and wastewater industries. In particular, the multi-plate interlocking design and the continuous cyclic chain-driven design reduce the auxiliary time per cycle, increase production volume, and generate significant economic benefits for customers. Single pawl, multiple pawls; chain drive with interlocking filter plates. For a long time, the automatic cake discharge from filter presses has been a persistent problem that hinders the complete automation of these machines. Due to the inherent properties of certain filter cakes, adhesion between the filter cake and the filter cloth occurs, making cake discharge difficult. Through years of research and development as well as the accumulation of experience, Andritz has developed a variety of mature automatic cake-unloading mechanisms. Depending on the type of material, different automatic cake-unloading mechanisms are selected, thereby replacing the initial manual operation with fully automated processes. The automatic cake-unloading devices have taken the place of manual unloading methods, **reducing the workload and improving work efficiency. The long-frame cake unloading device utilizes the vibration of the frame when the pull plate is moved to cause vibration of the filter cloth, thereby enabling rapid cake unloading ； When dealing with sludge with high viscosity, a fully automatic scraper device is generally used to assist the filter press in discharging the cake through external force. The filter cloth of the fully automatic scraper device is a key component of plate and frame filter presses. The material of the filter cloth, its weaving method, air permeability, and surface treatment methods are important parameters for evaluating it; the selection of the filter cloth usually requires testing ； Application of gasketed filter cloth enhances the filtering efficiency, reduces deformation of the filter cloth under pressure, and prolongs its service life. The filter cloth cleaning process is becoming increasingly important during the operation of filter presses. High-pressure cleaning water at 10 MPa can penetrate the filter cloth, thoroughly cleaning any dirt that may be present on the filter cloth as well as on the filter plate behind it. The cleaning device operates fully automatically to clean the filter cloth, and it is not necessary to remove the filter cloth during cleaning. The diaphragm pressing technology of the automatic filter cloth cleaning device represents an important technological advancement for plate and frame filter presses; it **increases the solid content of the filter cake and reduces the processing time. By using diaphragm extrusion technology, the solid content of the filter cake can be increased by about 5% to 40%. The media used for diaphragm pressing are usually water and air; air pressing is generally employed in small filter presses or in applications where the pressing pressure is low ； On large diaphragm filter presses or at high pressures, water is typically used as the medium for squeezing the diaphragm. The water used for extrusion can be recycled, while also ensuring the safety of the extrusion system. The quality of the diaphragm filter plate directly affects the extrusion pressure, which in turn influences the solid content of the filter cake. Typical application examples of inclined long frames: 1. Application in water treatment plants. Sludge dewatering in water treatment plants is an environmental protection treatment process that has gradually developed in China since the year 2000. Before any dewatering treatment is applied, most of the sludge from water treatment plants is discharged directly into water bodies, causing the riverbeds to rise. The water purification chemicals present in this wastewater contaminate the water bodies, leading to environmental pollution. Now, the sludge from water treatment plants is collected and concentrated, then dehydrated using diaphragm filter presses. The filter cake is taken away for landfilling or reuse, while the filtrate is sent to sewage pipelines for further treatment, thereby eliminating the pollution caused by direct discharge of sewage. The fully automatic diaphragm filter press is the best equipment choice for sludge dewatering in water treatment plants. ■After dehydration, the sludge cake has a high solid content, reducing the costs associated with its transportation and further processing ； ■Low noise is a very important requirement for water treatment plants located in urban areas ； ■Low operating costs; the consumption of electricity, water, and chemicals is **lower than that of other dehydration equipment. Fully automatic operation saves a great deal of labor ； ■It has strong adaptability, coping well with different types of sludge and fluctuations in the solid content of sludge, without the need to adjust the equipment. The filter press sludge dewatering equipment at Wuxi Meiyuan is the first, and currently the only, fully automatic diaphragm filter press system to be successfully operational in the Taihu Lake area. The water quality in Taihu Lake is poor, with high levels of algae, which makes sludge dewatering a very challenging task. The excellent diaphragm filter press system at Wuxi Meiyuan Water Plant achieves a solid content of over 40%~50% in the sludge cake after dewatering, and the equipment operates in a fully automatic manner. This project is highly representative of sludge dewatering projects in water treatment plants. Another representative sludge dewatering equipment used in water treatment plants is that of the **Dapu Water Treatment Plant**. This plant employs a static water treatment process based on air flotation (FGD); the sludge contains many microbubbles, which leads to sludge bulking and makes dewatering extremely difficult. Through a combination of processes such as stirring for degassing, fully automatic diaphragm pressing, and the selection of dosing methods, **Dapu Water Treatment Plant achieves excellent sludge dewatering results; the solid content of the sludge cakes after dewatering is above 35%, ensuring optimal operation. At present, water treatment plants in cities across China such as Taiyuan, Shenzhen, Wuxi, Suzhou, Guilin, Hangzhou Binjiang, and Taizhou in Zhejiang Province all use fully automatic diaphragm filter presses for dewatering. 2. Applications in steel mills: Diaphragm box filter presses are widely used in the sludge treatment processes across various sections of steel mills. They are an essential part of these sludge treatment systems, offering advantages such as corrosion resistance, ability to withstand wear from high-hardness solid particles in sludge, low operating costs, and ease of adjustment. ■ Ironmaking plants: Sludge treatment system for cleaning blast furnace gas ； ■Steel mill: Lime storage, transportation, cleaning, and sludge treatment system ； ■Continuous casting sludge treatment system (oily) ； ■Blast furnace dust removal OG sludge treatment system in steel mill ； ■Steel mill: Cold rolling silicon removal sludge treatment system, cold rolling wastewater and sludge treatment system, hot rolling wastewater and sludge treatment system (oily) ； ■Central Sewage Plant: Wastewater and sludge treatment system for steel mills ； ■Raw water plant: Sludge treatment system for raw water from steel mills. 3. Application in production processes: In addition to sludge filtration, diaphragm box presses are also widely used in various production processes. The requirements are: acid and alkali resistance, oxidation resistance, CIP cleaning, as well as cake washing and extrusion processes, to ensure high-quality products and adequate processing capacity. Antibiotics, mycelium, active pharmaceutical ingredients, traditional Chinese medicine, pharmaceutical intermediates, blood products, biological products ； ■Silica gel, water glass, gypsum, cement ； ■Titanium dioxide (including 11 processes) ； ■Various dyes, pigments, additives, and intermediates ； ■Bentonite, kaolin, sulfur/phosphorus products ； ■Malt extract, yeast, sugar, sweeteners, edible oil. Filter presses have been used for sludge dewatering and industrial production for over a hundred years, and they have undergone significant changes and technological advancements, evolving from manual to fully automatic systems. These technological innovations have made filter presses more effective in the field of solid-liquid separation, leading to a significant improvement in their operating conditions and making fully automated operation more user-friendly. Thanks to its excellent performance, the application scope of filter presses has been further expanded. Andritz Filtration Technology Company has a long history in wastewater treatment, offers world-class products, and is able to provide customers with excellent services and products.