How Membrane Filter Presses Work In Sugarcane Juice Filtration

Membrane filter presses play a crucial role in sugarcane juice processing, particularly in the clarification filtration stage of the syrup filtration process, where they are used to separate the sediment (filter mud) formed during the clarification process from the clear juice.

The Core Function of a Membrane Filter Press: Solid-Liquid Separation

• After clarification:
  Before entering the evaporation and concentration process, sugarcane juice must undergo clarification treatment (typically including heating, adding lime, sulfur fumigation, flocculation, etc.) to remove impurities such as colloids, pigments, and suspended solids. This process produces a large amount of sediment (commonly known as “filter mud”).
• Separation requirements:
  To obtain pure, clear juice suitable for subsequent evaporation crystallization and recover valuable sugar content, it is essential to efficiently separate these filter muds from the juice.
• The Filter Press Takes Center Stage:
  The filter press is the key equipment responsible for this solid-liquid separation task. It utilizes a filter medium (filter cloth) and externally applied high pressure to retain the filter sludge on the filter cloth surface, forming a filter cake, while the clear juice passes through the filter cloth and flows out.

Important Notes

• Screening:
  Before entering the clarification system and before entering the filter press after clarification, sugarcane juice must undergo multi-stage screening (e.g., curved screens, vibrating screens) to remove larger sugarcane husks, fiber fragments, etc. Failure to do so may severely clog the filter cloth, reducing efficiency and service life.
• Clarification Effectiveness:
  The clarification process (lime addition rate, heating temperature, flocculant usage, etc.) must be stable and effective. Forming flocculants of appropriate particle size and ease of filtration is a prerequisite for efficient filter press operation. If sediment particles are too fine or have poor settling properties, it will lead to filtration difficulties, turbid filtrate, and high moisture content in the filter cake.
• Temperature control:
  Sugarcane juice is typically maintained at a high temperature (80–105°C) when entering the filter press. High temperatures reduce viscosity, which facilitates filtration speed.

Sedimentation and Clarification of Sugarcane Juice

The addition of calcium hydroxide in the clarification process prior to sugarcane juice filtration is a core step in the sugar manufacturing industry. It prevents sucrose from hydrolyzing into glucose and fructose under acidic conditions (conversion sugar produces pigments at high temperatures, reducing sugar quality) and creates the optimal pH environment for subsequent calcium phosphate flocculation.

Advantages of Filter Presses in Sugarcane Juice Processing

With their unique design and technical advantages, membrane filter presses have become the preferred choice for modern sugar mills to replace traditional equipment in sugarcane juice filtration. Membrane filter presses operate at relatively high pressures, and with secondary pressing technology, they can significantly reduce the moisture content of filter cakes. They can also wash the filter cakes to fully replace the sugar content in them.

• High-quality filtrate: Produces very clear juice with high light transmittance and low suspended solids content.
• High filter cake dryness: High-pressure pressing significantly reduces filter cake moisture content (typically lower than vacuum filter presses), minimizes sugar loss (lower sugar content in filter cake), and reduces filter cake processing volume and costs.
• High degree of automation: Membrane filter presses can achieve highly automated operations (feeding, pressing, unloading, and cleaning).
• Strong adaptability: Adaptable to fluctuations in clarification effectiveness (relative to vacuum filter presses).
• Good: Reduces juice exposure, benefiting hygiene and minimizing heat loss.
• Washing process The washing process reduces residual sugar content to below 0.4%.