From Water Shortage to Water Surplus: Sludge Dewatering with a Geotextile Tube at a Chrome Plant
Updated: Aug 31
Water recovery is a critical part of any mineral processing operation. At a recent chrome processing site, the challenge was not simply the availability of water — it was the ability of the existing system to recover sufficient clean water for reuse in the plant.
The client approached Terravua after experiencing difficulties with the existing cyclone and site-based water recovery equipment. The system was not producing enough clean return water to satisfy the plant's processing requirements.
Rather than immediately specifying equipment, Terravua started with the material itself.
Testing the Chrome Sludge compatibility with Sludge dewatering geotextile tubes
Samples from the site were tested to determine how effectively the suspended solids could be separated from the process water and whether geotextile tube dewatering would provide a suitable solution.
Using a Terravua-supplied flocculant, testing showed a strong response.
From a 500 ml sludge sample, approximately 300 ml of clear filtrate could be released during the dewatering test.
The testing also demonstrated:
Approximately 98% solids retention
High-quality clarified filtrate
Final dewatered material with approximately 46% moisture content
Strong floc formation using the selected polymer
These results gave the project team confidence that a full-scale geotextile tube dewatering system could achieve two important objectives simultaneously: retain the chrome solids while recovering clean water for reuse.
It is important to distinguish between solids retention and final solids concentration. The approximately 98% figure refers to the percentage of suspended solids captured by the dewatering system, while the 46% moisture result describes the condition of the dewatered material after water removal.
Designing the Complete Dewatering System
Once the material testing had demonstrated that the process was viable, Terravua developed a site-specific layout and dewatering plan.
The project was approached as a complete process system rather than simply the supply of geotextile tubes.
The installation included:
An HDPE-lined dewatering area
Geotextile dewatering tubes, TITANtube
A flocculant preparation and dosing system designed and constructed by Terravua
Process pipework
Static mixers for improved flocculant and sludge interaction
Controlled chemical injection points
Sampling points for monitoring the process during operation
This allowed the polymer dosing, slurry flow and tube performance to be monitored and adjusted during commissioning.
For fine mineral sludge, this process control is particularly important. The performance of a dewatering tube is influenced not only by the fabric, but also by the condition of the material entering it.
Effective flocculation allows the suspended particles to form larger flocs that can be retained by the geotextile while water passes through the fabric as filtrate.
Taking the System from Laboratory Testing to Site Operation
Laboratory and material testing provide the basis for a dewatering design, but the real measure of the system is its performance once pumping begins.
During commissioning of the chrome sludge dewatering system, Terravua monitored the flow, dosing response, filtrate quality and behaviour of the material inside the tubes.
The geotextile fabric used for the system has a laboratory water-flow performance of approximately 1,400 L/min/m².
Under actual operating conditions with the chrome sludge, an approximate through-flow performance of 850 L/min/m² of fabric was observed.
The difference between clean-water fabric testing and actual sludge performance is expected. Once solids, flocculated particles and the developing filter cake are introduced, the material itself becomes part of the filtration mechanism.
What mattered operationally was the quality and quantity of the filtrate being recovered.
The system was producing a high volume of visibly clean water that could be collected and returned to the plant for reuse.
From Not Enough Clean Water to More Than the Plant Required
The original problem presented to Terravua was straightforward: the plant was struggling to recover enough clean water from its existing process to meet operational requirements.
Following installation and commissioning of the geotextile tube dewatering system, that position changed significantly.
Water released from the tubes could be recovered and returned to the process circuit instead of remaining trapped within the sludge stream.
The improvement was significant enough that the plant manager remarked that the operation now had “too much water.”
For Terravua, that comment captures the objective of the project better than almost any technical measurement could.
The project did not create additional water.
It allowed the plant to recover and reuse water that was already within its process.
More Than a Geotextile Tube
This project also demonstrates why effective sludge dewatering requires more than selecting a tube and connecting a pump.
Successful implementation required:
Material testing → flocculant selection → system design → site layout → dosing equipment → pipework and static mixing → controlled filling → sampling → commissioning and optimisation.
The geotextile tube is an important component of the process, but the overall performance comes from ensuring that every part of the system works together.
By combining sludge testing, chemical conditioning, purpose-designed dosing equipment and geotextile tube dewatering, Terravua was able to provide the chrome processing plant with a practical method of capturing solids while recovering valuable process water.
Recover the Water Already in Your Process
For chrome plants and other mineral processing operations experiencing poor water return, high suspended solids or difficult-to-manage sludge, the first question should not always be:
“Where can we get more water?”
A better question may be:
“How much of the water already in our process can we recover?”
Terravua provides sludge testing, geotextile dewatering system design, flocculant selection, dosing systems, installation support and commissioning for mining and industrial applications.
Don't get stuck in the sludge. Talk to Terravua about recovering the water already in your process.
