Case Study: Geotube Sludge Dewatering at HOKBG Yueyang Lake Project
Case Study: Geotube Sludge Dewatering at HOKBG Yueyang Lake Project
Lake and river dredging projects often face a major challenge after sediment is removed from the water: how to efficiently separate water from sludge and handle the large volume of wet sediment.
At HOKBG's Yueyang Lake project, geotextile tubes were used as part of the sludge dewatering solution. The system provided a practical way to contain dredged sediment, allow water to drain through the geotextile fabric, and progressively consolidate the retained solids.
This case demonstrates how geotextile tubes for sludge dewatering can be applied to lake dredging and environmental engineering projects.
1. Project Background
Yueyang is located in Hunan Province, China, within the Dongting Lake region. Lake and water-environment improvement projects in the area have included sediment dredging and water-quality restoration.
For example, publicly available project information from Yueyang shows that regional water-environment projects have included large-scale bottom-sediment dredging and treatment. One Dongting Lake basin environmental project reported approximately 257,000 tonnes of sediment dredging as part of a broader water-environment improvement program.
In another Yueyang lake remediation program, approximately 600,000 m³ of sediment was reported to have been dredged from five black and odorous water bodies in the Dongfeng Lake area.
These projects illustrate the importance of efficient sediment handling and dewatering technologies in lake restoration.
2. The Challenge: Large Volumes of Wet Sediment
Dredged lake sediment normally contains a high proportion of water.
If wet sludge is transported or disposed of directly, the project may face several problems:
• High transportation volume
• High water content
• Large temporary storage requirements
• Difficult sediment handling
• Slow natural drying
• Increased land requirements
• Complicated sludge disposal
Traditional sediment treatment methods may require large drying areas, mechanical dewatering equipment or multiple handling stages.
For projects with limited land availability, a more efficient method of separating water from dredged sediment can significantly simplify site management.
3. Why Use Geotextile Tubes for Sludge Dewatering?
A geotextile tube is a large permeable container manufactured from high-strength geotextile fabric.
The basic working principle is:
Dredged Sludge → Pumping → Geotextile Filtration → Water Drainage → Solid Retention → Consolidation
The dredged slurry is pumped into the tube.
Water passes through the specially designed geotextile fabric, while the majority of the solid particles are retained inside the tube.
As water continues to drain, the sediment gradually consolidates and becomes easier to manage.
This principle is widely used in sludge and sediment dewatering applications. Technical literature on geotextile tube systems also describes their use for retaining fines, silts and clays while allowing water to drain from the contained material.
4. HOKBG Yueyang Lake Solution
For the Yueyang Lake application, HOKBG used geotextile tubes as a sediment containment and dewatering solution.
The general process included:
Step 1 — Dredging
Sediment was removed from the lake using dredging equipment.
The dredged material was mixed with water, creating a pumpable sludge slurry.
Step 2 — Slurry Transportation
The sludge slurry was transported through a pipeline to the geotextile tube dewatering area.
The pumping system was arranged according to the site conditions and filling requirements.
Step 3 — Geotextile Tube Filling
The sludge was pumped into the HOKBG Geo Tube through designated filling ports.
During filling, the tube gradually expanded and formed its designed profile.
Operators monitored:
• Tube height
• Tube width
• Filling distribution
• Slurry flow
• Fabric condition
• Surrounding drainage
Step 4 — Water Separation
Once the slurry entered the tube, water began to drain through the permeable geotextile fabric.
The fabric retained most of the solid sediment particles while allowing water to pass through.
Step 5 — Sludge Consolidation
As drainage continued, the water content of the contained sediment decreased.
The sludge gradually consolidated, reducing its volume and making the material easier to handle.
5. Geotube Dewatering Process
The entire process can be summarized as:
Lake Dredging
Sludge Pumping
Geotextile Tube Filling
Water Filtration
Solid-Sediment Retention
Dewatering
Consolidation
Final Sediment Handling
This process allows dredging and dewatering to be carried out as an integrated operation.
6. Key Advantages of the HOKBG Geo Tube Solution
6.1 Large-Scale Sludge Containment
Geotextile tubes can contain large quantities of dredged sediment in a relatively controlled area.
This can reduce the need to handle wet sludge repeatedly during the initial dewatering stage.
6.2 Efficient Solid-Liquid Separation
The permeable geotextile fabric allows water to escape while retaining the majority of the sediment.
This creates a natural filtration and dewatering process.
6.3 Reduced Sludge Volume
As water drains from the contained material, the sediment consolidates.
The resulting material is generally easier to handle, transport or prepare for subsequent treatment.
6.4 Reduced Dependence on Large Drying Areas
Compared with simply spreading wet sediment over a large open area for natural drying, geotextile tubes can provide a more controlled dewatering footprint.
The actual land requirement depends on tube dimensions, sludge characteristics, filling height and project design.
6.5 Simple and Flexible Installation
Geotextile tubes can be installed on prepared dewatering platforms and arranged according to the available site area.
This makes them suitable for different lake, river and dredging projects.
7. What Happens to the Water?
Water separated from the sludge exits through the geotextile fabric.
However, the filtrate should not automatically be discharged directly into the lake or surrounding water body.
Depending on the sediment characteristics and local environmental requirements, the discharged water may require additional treatment, monitoring or clarification before final discharge.
This is especially important when dredged sediment may contain elevated levels of nutrients, organic matter, metals or other contaminants.
The final water-treatment requirements should therefore be determined through project-specific testing and applicable environmental regulations.
8. What Happens to the Dewatered Sludge?
After sufficient dewatering and consolidation, the sediment can be evaluated for its next treatment or disposal stage.
Depending on project requirements, potential options may include:
• Further natural drying
• Excavation and transportation
• Landfill disposal
• Soil improvement
• Landscape applications
• Reuse as fill material where permitted
• Other approved beneficial-use applications
The appropriate disposal or reuse method depends on the physical and chemical characteristics of the sediment and the applicable environmental requirements.
9. Key Factors Affecting Geotube Dewatering Performance
The performance of a geotextile tube is not determined by the fabric alone.
Important factors include:
Sludge Characteristics
Particle size, clay content, organic matter and initial water content can significantly affect dewatering performance.
Solids Concentration
The concentration of solids in the pumped slurry affects filling behavior and drainage.
Geotextile Fabric
Fabric strength, apparent opening size, permeability and filtration characteristics should be selected according to the project requirements.
Flocculant Selection
For some fine-particle sludges, an appropriate flocculant can improve particle settling and water separation.
Filling Rate
Excessive pumping rates can affect filtration and may result in uneven filling.
Tube Layout
The number, dimensions and arrangement of tubes should be designed according to available space and the required sludge capacity.
10. HOKBG High-Strength UV-Resistant Geo Tube
HOKBG provides high-strength UV-resistant Geo Tubes for sludge dewatering, dredging and marine engineering applications.
Depending on project requirements, HOKBG Geo Tube fabric can be designed with tensile strength ranging from approximately 35–250 kN/m.
The system can be customized according to:
• Tube dimensions
• Fabric strength
• Filtration requirements
• Filling port configuration
• Site conditions
• Sludge characteristics
• Project capacity
HOKBG Geo Tubes are suitable for:
• Lake sludge dewatering
• River dredging
• Dredged sediment management
• Industrial sludge dewatering
• Port dredging
• Land reclamation
• Artificial island construction
• Coastal engineering
11. Lessons from the Yueyang Lake Project
The Yueyang Lake project demonstrates an important principle:
Successful sludge dewatering depends on both the geotextile tube and the overall project design.
A suitable solution should consider:
• The type and properties of the sludge
• Required treatment capacity
• Available dewatering area
• Tube dimensions and fabric specifications
• Pumping and filling conditions
• Filtrate management
• Final sludge handling
• Environmental requirements
Simply selecting a large geotextile tube without considering these factors may not produce the expected result.
For this reason, project-specific technical assessment is recommended before ordering geotextile tubes.
12. Conclusion
The HOKBG Yueyang Lake project shows how geotextile tubes can be used for lake sludge dewatering and dredged sediment management.
By combining dredging, hydraulic pumping, geotextile filtration, water separation and sediment consolidation, the system provides a practical approach for handling wet sludge.
For lake restoration and dredging projects, geotextile tubes can help create a controlled dewatering area while reducing the volume and water content of retained sediment.
