Tronox

At Tronox, we’re committed to managing the Kwinana Pigment Plant in an environmentally responsible manner – that means using water more sustainably and reducing our reliance on scheme
water.

Reducing our reliance on scheme water

Since plant commissioning over 30 years ago, we’ve been evaluating ways to reduce our water consumption and demand on scheme water.

To reduce our reliance on scheme water, we have diversified our water sources to use recycled brackish water, recycled water from the Kwinana Water Reclamation Plant and groundwater.

One of our methods is matching the quality of water used in the operational process and leveraging alternative water sources such as recycled industrial wastewater instead of scheme water. This includes maximising non-scheme water supply options by:

• Implementing reuse and recycling initiatives such as using recycled process water (brackish water) in areas of the process such as pigment manufacturing circuit and for washdown.
• Implementing efficiency initiatives for the main scheme water users in the plant such as firewater, potable water, cooling water towers and the pigment wash circuit. Some of initiatives include:
  • repairing leaks
  • restricting the use of scheme water
  • investing into water efficient equipment
  • optimising the computer logic to ensure minimum water is used

At the plant, we require higher quality water with fewer impurities, resulting in a higher-quality finished product. It also means that there is less chance of scale build-up in our pipes and vessels over time, which can lead to leaks and higher maintenance costs.

Signs are implemented around the plant to remind everyone about using brackish water.

In 2021, our efforts to further optimise our operations and increase efficiencies lead to a 10% reduction in ground water use, despite production increasing by around 20%.

“Tronox is committed to managing the plant in an environmentally responsible manner and to use natural resources efficiently. Since operations commenced in 1991 the business has reduced scheme water use from about 57kL/t of pigment to around 5kL/t of pigment in 2021.”

How we did it

One of our approaches is using recycled process water (brackish water) to reduce scheme water use. Brackish water has a higher solids content compared to other water types. Most water has some solids content in it – including drinking water. The solids content in the brackish water isn’t suitable for drinking water, however it’s safe to use for our operational and washdown purposes.

We’ve looked at where in the pigment manufacturing process we can use the lower quality water. For example, we use brackish water in the process areas where the higher solids water will not affect the quality of the finished product.

Our brackish wastewater is directed to the onsite wastewater treatment plant. Following treatment, the water is transferred to a holding pond, where we can recover and reuse it within the plant.

Holding pond where the recycled water ‘brackish water’ is stored ready for use.

Pumps and pipework have been installed to deliver the brackish water where it’s used within the plant and to hose reel stations. We use brackish water from these hoses to conduct daily “washdown's” – regular cleaning of our facilities and equipment. Brackish water hose reels are green to make them easily identifiable from the red scheme water hose reels.

Maintaining the water quality

Our main challenge for moving away from scheme water use, was ensuring the availability and volume of good-quality non-scheme water sources.

Some brackish water use was included in the original plant design, but this was initially only used to help move the waste through the pipelines. As operations progressed, we identified more opportunities and the system has improved in many stages over the years. This includes installing hose reels at various locations for washdown purposes on sealed ground.

Using brackish water can be challenging due to scaling of pipework. This is because brackish water has a higher solids content than scheme water, which can cause blockages in the pipes. Over time, piping material specifications for brackish water has improved, which has minimised this issue. Carbon steel used to be the only material approved, but we can now use HDPE in some areas not affected by the temperature from adjacent equipment.

Strategically maximising non-scheme water sources

We have a designated process engineer that forecasts our water requirements, selection of water source (choosing the right source of water for the task) and reviewing trends monthly. Water is segregated into different tanks depending on quality and source and this approach facilitates tracking of our water use.

What we're doing now

We completed an upgrade to our brackish water system. This involved replacing blocked and corroded pipework to improve the availability and volume of brackish water we use.

We’re also upgrading our aging scheme water pipeline, which supplies all our plant scheme water. Previously, the main pipeline has been repaired many times in different locations due to leaks. Replacing the pipeline will reduce leaks and overall water wastage, improving water conservation and efficiency at the plant.

We operate under an ISO14001 certified Environmental Management System and actively seek opportunities for continuous improvement. We have a team of business improvement engineers that are responsible for the ongoing evaluation of new technologies and implementing improvement projects. This includes identifying additional areas where brackish water can be used.