How does a Geotube Work & How much do Geotubes Cost?

Geotubes are large tubular containers sewn from high-strength woven geotextile. They are related to smaller sand-filled geo bags, but are much bigger and are filled hydraulically. Because they are simple and cheap to run, they are used for sludge dewatering projects of many sizes.
For marine and shoreline work, the tube is pumped full of a slurry of sand and water. Pump pressure carries the sand along the inside of the tube, the water escapes through the permeable fabric, and the sand settles out inside the container by gravity.

The Geotube system is used for shoreline protection, land reclamation, island and wetland creation, construction platforms, revetments, dykes, groynes and offshore structures.

The system has no belts, gears or moving parts. Containers come in a range of sizes to suit the volume of sludge and the space available, and smaller units can be fitted in mobile roll-off containers that are moved around a site as needed.

Ocean Woven Geotube dewatering containers are made from an engineered woven textile that holds fine solids inside while letting water pass through. As the water drains, the solids densify and consolidate. Once they are dry enough to transport, or have met the site’s disposal requirements, the dewatered material can be disposed of in several ways.

The containers are prefabricated with high-strength seams into tubes, bags or other shapes, with filling ports for pumping on site. Each is sized for the job, so they work where land is limited, and the fabric and size are chosen to balance solids retention against the rate and clarity of the water discharged.

The Benefits of Ocean Woven Geotube Dewatering Containers at a Glance

• Large reduction in sludge volume, with the solids held inside the container
• Fast drainage of clear filtrate, which can be recirculated through the treatment system
• Containers sized to the site, so they need less land than drying beds
• Dewatered solids are easy to remove and handle
• Passive process: no mechanical presses or centrifuges, and little energy beyond pumping
• Works in most weather, with few moving parts for operators to work around
• Low capital and maintenance cost

How Does Ocean Woven Geotube Dewatering Technology work?

Dewatering with Ocean Global Geotube technology is a three-stage process:

Stage 1: Filling

Sludge is pumped into the Ocean Woven Geotube container. A polymer flocculant is dosed into the sludge on the way in, which makes the fine solids bind into larger flocs and release their water. The container’s fabric retains the flocculated solids.

Stage 2: Dewatering

Clear water drains out through the small pores in the textile, and the volume of material inside drops. That frees space, so the container can be filled again several times. The filtrate can be collected and recirculated, and depending on the sludge and the local discharge rules, it is sometimes clean enough to reuse in the process or return to a waterway without further treatment. Test the filtrate before discharge.

Stage 3: Consolidation

After the final fill-and-dewater cycle, the solids stay in the container and keep drying as residual moisture evaporates through the fabric. When this is complete, the container and its contents can go to a landfill or stay on site, or the solids can be removed and applied to land where that is permitted.

Advantages

• High flow rate through the fabric, so water leaves quickly and the solids stay behind
• Seams designed to withstand the pressure of pumping
• Size, shape and fabric can be specified for each project
• Sand-filled tubes also work as revetments, breakwaters, dykes and groynes

Functions and Applications

On site, the sequence is the same for every application: lay out and position the tube, condition the sludge with polymer, pump it in, let the clean water drain away, and repeat until the container is full of solids. The filled container then goes to landfill, or the solids are removed and applied to land.

Application

Geotube dewatering is used in:

• Pulp and paper mills
• Primary and secondary lagoon cleanout
• Mining and mineral processing, to dewater tailings
• Coal sludge
• Municipal wastewater treatment plants
• Marine and river sediment remediation
• Power and utility plants
• Light industry
• Agriculture, including dairies, piggeries and abattoirs
• Aquaculture

Geotube dewatering has also been used in wastewater treatment at dairy, poultry and other farm operations, where retaining the solids also lowers the BOD of the water discharged.

Also read about Top 5 Things you should know about Geotubes before using them.