I. Customer Background & In-Depth Needs Analysis

1.1 Customer Background

Located in Portugal's renowned Bairrada wine region, Quinta da Lagoa Velha is a family-owned winery with a winemaking heritage spanning three generations.

Founded by the Neto family in 1969, the winery has remained dedicated to producing wines that express the distinctive character of the Bairrada terroir. Today, Quinta da Lagoa Velha produces a diverse portfolio of wines, including red wines, white wines, sparkling wines, and fortified wines.

The winery combines traditional winemaking experience with modern cellar practices. Its wines undergo extended natural settling following fermentation, creating the need for a carefully designed filtration strategy that can progressively remove suspended solids and fine impurities while preparing the wine for stable final bottling.

For a winery with a diverse product portfolio, filtration is not simply about achieving visual clarity. The filtration process must also balance particle removal, microbiological stability, filtration capacity, and the preservation of the wine's essential sensory characteristics.

To support the winery's production requirements, LOONG Filtration designed a customized multi-stage wine filtration system based on a processing capacity of 3,000 L/h.

1.2 The Challenge: From Naturally Settled Wine to Stable Bottling

After fermentation, the wine is naturally settled for approximately 4–6 months before entering the filtration process.

Although this extended settling period allows a significant portion of suspended solids and lees to settle naturally, the wine may still contain residual impurities, including:

• Fine suspended particles

• Residual lees

• Tartrate crystal fragments

• Fine colloidal substances

• Residual yeast cells

• Other microbiological contaminants

The challenge is that these contaminants cannot be efficiently managed by relying on a single filtration stage.

If a fine or sterile membrane filter is used directly on wine with a high particle load, the filter can become rapidly loaded, resulting in premature clogging, unstable flow, and increased filtration costs.

At the same time, the final filtration process must achieve a high level of microbiological control without unnecessarily compromising the wine's color, aroma, tannins, body, and overall sensory characteristics.

Therefore, the filtration system needed to achieve three key objectives:

1. Progressively reduce the particle and colloidal load

2. Protect high-precision downstream filtration stages from premature blockage

3. Provide reliable terminal sterile filtration before bottling

The solution was not to rely on one filter, but to design a progressive, multi-stage filtration system in which each stage performs a specific filtration function.

1.3 Design Basis

To resolve these challenges, LOONG Filtration designed a progressive, multi-stage filtration system based on the following operating conditions:

II. LOONG Filtration's Customized Multi-Stage Solution

To meet the winery's requirements, LOONG Filtration designed a six-stage wine filtration process with a nominal capacity of 3,000 L/h.

The complete filtration sequence is:

Each stage has been carefully selected to perform a specific filtration function while reducing the burden on the subsequent stage.

2.1 Stage 1: Coarse Pre-Filtration

Equipment: Bag Filter

Filter Rating: 5 μm

• Filter Size: Size 2

• Inlet & Outlet: Tri-clamp DN40

The first stage serves as the primary protective barrier for the entire filtration system.

Even after 4–6 months of natural settling, the wine may still contain larger suspended particles, residual lees, and fragments of tartrate crystals.

The 5 μm bag filter is designed to capture these larger contaminants before the wine reaches the more precise downstream filtration stages.

Key Functions:

• Remove larger suspended solids

• Capture coarse lees residue

• Retain tartrate crystal fragments

• Reduce the initial contaminant load

• Protect downstream fine filters

With its high dirt-holding capacity and relatively low operating cost, the bag filter provides an efficient first line of defense.

By removing the larger particle load at the beginning of the process, it helps reduce the risk of premature loading of the more expensive downstream filter media.

2.2 Stage 2: Clarification and Semi-Fine Filtration

Equipment: Lenticular Filter

• Filter Rating: 1–3 μm

• Filter Dimensions: 16 inches

• Filter Configuration: 16 cells

• Housing Configuration: 2 stacks

• Inlet & Outlet: Tri-clamp DN40

After coarse pre-filtration, the wine enters the lenticular depth filtration stage.

Unlike surface filtration, depth filtration provides a three-dimensional filtration matrix that allows particles to be retained throughout the depth of the filter media.

This stage is designed for deeper clarification and semi-fine filtration.

It helps remove:

• Fine suspended particles

• Haze-forming colloidal substances

• A portion of residual yeast cells

The lenticular depth filter also provides high dirt-holding capacity and colloid retention, helping to progressively clarify the wine while maintaining its essential sensory characteristics, including its body and color.

This stage plays a critical role in preparing the wine for the finer filtration steps that follow.

2.3 Stage 3: Intermediate Pre-Filtration

Equipment: PP Pleated Filter Cartridge

• Filter Rating: 0.65 μm

• Filter Cartridge: PP Pleated Filter

• Configuration: 5 cores

• Length: 30 inches

• Inlet & Outlet: Tri-clamp DN40

The third stage introduces a precision pleated cartridge filtration step.

The 0.65 μm PP pleated filter cartridge functions as a security filter positioned upstream of the final filtration stages.

Its high-surface-area pleated structure provides effective removal of remaining micro-particles and trace fibers that may pass through the previous depth filtration stage.

Key Functions:

• Capture fine micro-particles

• Remove trace fibers

• Provide additional security filtration

• Reduce the contaminant burden on downstream filters

• Extend the service life of the final sterile membrane

This stage acts as an important transition between depth clarification and the final high-precision filtration process.

By reducing the remaining particle load before the final stages, the 0.65 μm PP pleated cartridge helps protect the more sensitive downstream filtration media.

2.4 Stage 4: Fine Clarification and Deburdening

Equipment: Lenticular Filter

• Filter Rating: 0.2–0.4 μm

• Filter Dimensions: 16 inches

• Filter Configuration: 16 cells per stack

• Housing Configuration: 2 stacks

• Inlet & Outlet: Tri-clamp DN40

The fourth stage provides an additional level of fine clarification and biological deburdening.

At this point in the process, the majority of larger particles have already been removed.

The 0.2–0.4 μm lenticular filtration stage is therefore focused on reducing the remaining micro-particulates, fine colloids, and a significant portion of residual yeast and spoilage bacteria.

Key Functions:

• Remove remaining micro-particulates

• Reduce fine colloidal substances

• Further reduce residual yeast

• Reduce spoilage bacteria

• Significantly lower the biological load before terminal filtration

This stage is particularly important because it prepares the wine for the final sterile filtration step.

By significantly reducing the bioburden before the final membrane filter, the system creates a cleaner feed condition for terminal sterile filtration.

2.5 Stage 5: Hot Water Sterilization in Place (SIP)

Integration Point: Between Stage 4 and Stage 6

Before the wine reaches the final sterile filtration stage, the system incorporates a Hot Water Sterilization in Place (SIP) process.

The SIP stage is designed to sanitize the downstream filter housing, sterile filter cartridges, and connecting pipework before bottling.

Key Functions:

• Sanitize the downstream filtration system

• Reduce the risk of secondary microbiological contamination

• Prepare the system for sterile bottling

• Support hygienic operation of the final filtration stage

This step is essential because terminal sterile filtration alone is not sufficient if the downstream equipment and piping are not properly sanitized.

By integrating hot water sterilization into the process, the system provides a controlled sanitary environment between fine clarification and final sterile filtration.

2.6 Stage 6: Terminal Sterile Filtration

Equipment: Sterile PES Pleated Filter Cartridge

• Filter Rating: 0.22 μm Absolute Grade

• Membrane Material: Polyethersulfone (PES)

• Configuration: 5 cores

• Length: 30 inches

• Inlet & Outlet: Tri-clamp DN40

The final stage is the terminal sterile filtration step.

The 0.22 μm absolute-grade PES pleated filter cartridge is designed to provide the final microbial barrier before bottling.

The filter is designed to remove residual yeast and microorganisms, including:

• Yeast

• Acetic acid bacteria

• Lactic acid bacteria

The hydrophilic PES membrane offers low protein binding and high flow performance, supporting efficient final filtration while minimizing unnecessary interaction with the wine.

The purpose of this final stage is to achieve cold microbial stabilization and provide a reliable filtration barrier immediately before bottling.

III. The Complete Filtration Journey

The key advantage of the LOONG Filtration system is that the wine is not forced through a single high-precision filter from the beginning.

Instead, the filtration load is progressively reduced through six carefully designed stages.

Wine Ready for Stable Bottling

This progressive filtration architecture ensures that each filtration stage performs a defined role, from coarse particle removal to final microbial stabilization.

IV. Value Delivered by the Integrated Filtration Strategy

4.1 Progressive Reduction of Filtration Load

Instead of placing the entire contaminant burden on the final sterile membrane, the system removes impurities progressively.

This staged approach helps distribute the filtration workload across multiple filtration technologies.

4.2 Protection of High-Precision Terminal Filters

The 0.65 μm PP pleated filter and 0.2–0.4 μm lenticular filtration stages act as important protective barriers before the final 0.22 μm PES sterile membrane.

This helps reduce the risk of premature clogging and supports more stable terminal filtration.

4.3 Improved Filtration Stability

The combination of bag filtration, depth filtration, pleated cartridge filtration, and sterile membrane filtration creates a controlled filtration pathway.

Each stage removes a specific range of contaminants, helping the overall system operate in a more stable and predictable manner.

4.4 High-Level Clarification and Microbial Control

The multi-stage process progressively removes suspended solids, colloidal substances, yeast, and microbiological contaminants.

The final 0.22 μm absolute PES sterile filter provides the final filtration barrier before bottling, supporting cold microbial stabilization.

4.5 Designed for Wine Quality Preservation

The filtration strategy is designed to achieve high levels of clarification and microbiological control while minimizing unnecessary impact on the wine's essential characteristics.

The system is therefore designed with a clear objective:

To achieve the required filtration performance without unnecessarily stripping the wine's color, aroma, tannins, and body.

V. FAQ

1.Why is a multi-stage filtration system necessary after 4–6 months of natural settling?

Natural settling can significantly reduce the amount of suspended solids in wine, but it does not necessarily remove all fine particles, colloids, residual yeast, or microorganisms.

A multi-stage filtration process allows these contaminants to be progressively removed according to their size and characteristics.

This also prevents the final sterile membrane from receiving the entire contaminant load at once.

2.Why use a bag filter before the lenticular filter?

The 5 μm bag filter serves as the first protective barrier.

It removes larger suspended solids, coarse lees residue, and tartrate crystal fragments.

By reducing the larger particle load at the beginning of the process, it helps protect the downstream lenticular and cartridge filters from excessive loading.

3.What is the role of the 0.65 μm PP pleated filter?

The 0.65 μm PP pleated filter acts as an intermediate security filter.

It captures fine micro-particles and trace fibers that may remain after the previous clarification stages.

Its primary purpose is to provide additional protection for the downstream fine clarification and terminal sterile filtration stages.

4.Why is another lenticular filtration stage used after the 0.65 μm pleated filter?

The two lenticular filtration stages perform different functions.

The first 1–3 μm lenticular filter focuses on deep clarification and semi-fine filtration.

The later 0.2–0.4 μm lenticular filter provides finer clarification and biological deburdening, significantly reducing the remaining microbial load before the final sterile membrane.

This progressive approach helps ensure that the terminal filter receives a much cleaner feed.

5.Why is hot water SIP integrated before terminal sterile filtration?

The final sterile filter can only provide reliable sterile filtration if the downstream filtration system itself is properly sanitized.

Hot water SIP is integrated between the fine clarification stage and the terminal sterile filter to sanitize the downstream housing, cartridges, and connecting pipework.

This helps reduce the risk of secondary microbiological contamination before bottling.

6.Why is a 0.22 μm absolute PES filter used as the final stage?

The 0.22 μm absolute-grade PES pleated membrane serves as the terminal sterile filtration barrier.

Its purpose is to remove residual yeast and microorganisms before bottling, supporting cold microbial stabilization.

PES is also well suited to this application because of its hydrophilic properties, high flow performance, and low protein binding characteristics.

VI. Partner with LOONG Filtration for Customized Winery Solutions

At LOONG Filtration (Zhejiang Loongfiltech Equipment Co., Ltd.), we deliver engineered liquid microfiltration solutions for global beverage producers. From complete sanitary stainless steel housings and lenticular depth modules to absolute-grade PES membrane cartridges, our technical team builds systems tailored to your specific flow rate, batch volume, and wine profile.

Looking to optimize your winery filtration process? Contact a LOONG application specialist today to request customized engineering drawings and direct factory quotes!