Application of Geomembranes in Seawater Fish Farming

Geomembranes, also known as impermeable membranes, are increasingly being used in seawater fish farming due to their excellent performance and multiple advantages. Here is a detailed introduction to their applications:

1. Pond Lining System

• Purpose: Used as a liner for aquaculture ponds, raceways, or tanks to create a fully enclosed and isolated water environment.

• Function:

• Seepage Prevention: Effectively prevents seawater from infiltrating the soil and stops groundwater or contaminants from entering the pond. This maintains stable water levels and salinity.

• Water Quality Control: Isolates the pond water from the soil, reducing the risk of pollution from soil-borne pathogens, heavy metals, or other harmful substances. This facilitates better management of water quality.

• Disease Prevention: By isolating the culture environment from the natural seabed, it significantly reduces the introduction and spread of pathogens from the substrate, thereby lowering the incidence of diseases.

2. Biosecurity and Environmental Protection

• Waste Management: Facilitates the collection of fish waste (feces, uneaten feed). This prevents waste from directly entering and polluting the surrounding marine environment, allowing for centralized treatment and reducing environmental impact.

• Preventing Cross-Contamination: In coastal areas, it prevents potentially polluted groundwater from entering the ponds and, conversely, stops pond water (which may contain medications or excess nutrients) from seeping into the local aquifer.

3. Key Advantages

• Durability: High-quality geomembranes (such as HDPE) are resistant to corrosion, UV radiation, and puncture, making them suitable for long-term use in harsh marine environments.

• Flexibility: They can be customized to fit ponds of various shapes and sizes, making them highly adaptable.

• Smooth Surface: The smooth surface makes pond cleaning and disinfection easier and more thorough between production cycles.

• Improved Growth Efficiency: By enabling superior control over the water environment, geomembranes contribute to improved fish health and growth rates.

4. Material Selection

• HDPE (High-Density Polyethylene): This is the most common choice due to its excellent chemical resistance (to seawater, salts), strong mechanical properties, and good UV resistance. It is the preferred material for most large-scale seawater aquaculture projects.

• LLDPE (Linear Low-Density Polyethylene): Offers greater flexibility and is suitable for projects with complex terrain or where higher elongation is required.

• Reinforced PVC: Sometimes used, but its long-term durability and chemical resistance in seawater are generally considered inferior to HDPE.

5. Application Process

• Site Preparation: The subgrade must be properly leveled, compacted, and cleared of any sharp objects (stones, roots) to prevent damage to the geomembrane.

• Installation: Geomembrane panels are deployed on the prepared subgrade and welded together using specialized hot wedge or extrusion welders to form a continuous, watertight seal.

• Protection: In some cases, a protective layer (such as a geotextile) may be installed above or below the geomembrane to provide additional puncture protection.

In summary, geomembranes play a vital role in modern, intensive seawater fish farming. They are a key technology for establishing a controlled, clean, and efficient aquaculture system, significantly enhancing both productivity and environmental sustainability.