Water treatment in the mining and metals industry enables benefits, both for the environment and the production
Access to water is crucial for the mining and metals industry, especially as the sector transitions to reduce its environmental impact
However, water availability is no longer guaranteed, making responsible management of this natural resource essential.
Historically, access to water has not been a major concern for Swedish industry. It was both easy and permissible to use large amounts of freshwater, with industries accepting the cost of pumping to maintain high water quality. Today, water management has shifted focus, becoming a top priority in efforts to achieve sustainable use and reduce climate impact.
Regulatory requirements and cost efficiency
Currently, stringent regulations on reducing water consumption are among the key factors driving the decrease in freshwater usage in industry. Advances in technology, along with innovations in circularity, have enabled greater reuse of water, helping to meet these regulatory demands.
Risks of reuse and recycling
The long-term goal of water management in the process industry is to reduce, reuse, and recycle industrial water. As the mining and metals industry relies heavily on water, effective water management and stewardship have become critical issues.
While recycling water is generally a straightforward and beneficial practice in most industries, over time, the water quality can decline due to the accumulation of contaminants. This deterioration can negatively affect the final product and potentially damage production equipment.
When striving for more sustainable water treatment practices, careful attention must be given to maintaining water quality, especially when recycling is involved.
Questions on the path to sustainable water treatment:
- Which water pollutants are easiest to treat?
- Which water treatment technologies are most suitable?
- What is the size of the water system?
Oil in water is a good example—it can be separated with relatively low effort. However, dissolved elements like zinc, sulphates, and certain organic compounds require more advanced treatment technologies.
Today, there are treatment options available for nearly all types of contaminants. Some are simpler, while others are more complex. The most appropriate technology depends on factors such as the type of contaminant, water temperature, and the desired final water quality.
Examples of water treatment techniques
- Mechanical Water Treatment: This method is effective for separating contaminants like oil or particles from water based on their physical properties. It is typically the least expensive treatment method, with common techniques including filtration, sedimentation, and oil separation. These processes use physical barriers or natural properties to separate contaminants from water.
Exception: Membrane technologies like ultrafiltration and reverse osmosis also use physical barriers to remove pollutants, but they come with more demanding operational requirements. - Biological Water Treatment: This approach is useful for removing organic pollutants. While it can treat various types of organic matter, the process can be slow. Biological treatment is also effective in removing nutrients like nitrogen and phosphorus from water. A well-managed system essentially enlists millions of bacteria to help achieve the treatment goals.
- Chemical Water Treatment: Historically the most common method, chemical treatment typically involves adjusting the pH of effluent water. Almost all contaminants can be removed chemically, and this method offers great flexibility in targeting specific pollutants. However, it can also become the most expensive option if tailored solutions are required to achieve optimal results.
For large industries with extensive water systems, high-capacity equipment and multiple units for each treatment stage may be necessary. However, existing infrastructure can often be adapted to enhance effectiveness, allowing simpler, add-on treatments to complement the system.
Smaller industries with lower water volumes face different challenges. The smallest equipment available may still be too large for the facility’s needs, and if multiple treatment stages are required, oversized equipment can complicate the operation of the water treatment process.
The early bird catches the worm
The sludge with the highest potential for successful recycling and reuse is that which captures contaminants as soon as they are generated. Sludges can become more difficult to manage when contamination occurs and are mixed together along the entire value chain. If a contaminant is captured before it mixes with additional pollutants or dilutes into more complex wastewater, it can often be more easily reused or up-cycled.
Biological sludge, for example, can often be repurposed to produce biogas, provided it doesn’t contain excessive metal contamination. Chemical sludge can sometimes be recycled through processes like leaching* if it contains high concentrations of a single metal. However, if the sludge contains a mix of various metals, recycling becomes more challenging.
*Leaching involves chemically dissolving the sludge, allowing for selective removal of certain contaminants.
Water quality requirements and sustainable water management
Water quality standards may be set by environmental permits or regulations when releasing treated water. However, when managing an increase in recirculated water there are other key aspects to consider. To ensure the long-term sustainability of the recycled water, treatment processes must remove more contaminants than the production process adds.
It’s important to remember that wastewater treatment doesn't just produce clean water—it also generates residual products, by-products, or sludge, which must be managed. This sludge, the by-product of creating clean water for reuse, can result in excessive costs if not factored into the design and operation of the treatment plant. Considering the entire value chain is essential. Unfortunately, the general perception has often been that water treatment plants are a necessary evil, adding no real value to production.
Water management in industrial plants
There are many ways to manage water usage in industries. It starts from water system design in the early phase of the new industrial plant development.
Consider the entire value chain
Whether you call it life cycle analysis or sustainable solutions, it's crucial to keep the entire production chain in mind. For instance, if the oil separated during treatment is of sufficient quality, it may hold great value for recycling companies, turning a potential waste product into a valuable by-product and a source of revenue, rather than a cost.
Never stop searching for the source of water pollution. Just because contaminants are "flushed away" from manufacturing or mechanical processes doesn’t mean the problem is solved. All drains lead somewhere, and preventing contaminants from entering the water in the first place offers significant benefits. While not every contaminant can be avoided, even small steps contribute to the greater good.
Resources and commitment: Maximising the return on investment
A water treatment plant requires the same level of commitment and access to resources as any other part of the business. The road ahead for water management and treatment is becoming increasingly complex, and it is beneficial to examine every aspect of the process to see if contaminants can be kept out of the water from the start.
Gone are the days when a single treatment method, such as pH adjustment, was sufficient to handle effluent before releasing it into receiving waters. Today, achieving required contaminant levels often involves a combination of mechanical, biological, and chemical treatment methods.
Financial considerations: Making the smart choice
As water treatment systems grow more complex, it’s perfectly reasonable to scrutinise the costs of an investment. However, opting for the cheapest solution can prove costly in the long run. The key is to make informed decisions and understand the difference between minimising costs and making a smart investment in water treatment.
A water audit is one tool that can help achieve optimal water efficiency. It can identify inefficiencies in a company's water use, uncover opportunities, and potentially lead to up to 10% water savings without any capital investment.
The bigger picture: Holistic water treatment solutions
At AFRY, we believe that water treatment plants deserve the same level of commitment and resources as any other part of the business. Water treatment processes are often among the most sensitive aspects of production. It's essential to explore the broader benefits of water treatment, such as energy or heat recovery. With modern technology, even low-temperature water can yield significant energy returns.
As water management and treatment challenges continue to evolve, it’s vital to examine each aspect of the process and consider ways to prevent pollutants from entering the water in the first place. After all, water treatment is a response to pollution that has already occurred—preventing it in the first place offers far greater benefits.
If you're considering a shift in how you manage water, it's time to let go of old mindsets and embrace the next generation of water treatment facilities. Contact us for support throughout the entire process, from feasibility studies to plant completion. A great starting point is a thorough analysis of your current situation.
