4 ways to reduce the use of harsh chemicals in water treatment
Read time: 9 minutes
Over the last few years, there’s been a shift in the water treatment industry towards utilizing materials that are less harmful to both people and our environment. This can be widely attributed to new regulations, technologies, and sustainable innovations.
Read on to uncover four ways the industry is treating water to be more efficient, effective, and sustainable.
Read on to uncover four ways the industry is treating water to be more efficient, effective, and sustainable.
Reverse osmosis in water treatment
Reverse osmosis is the process of using pressure to push unfiltered water through a semipermeable membrane to remove contaminants and ultimately create clean water. Of all the water treatment filtration approaches, microfiltration, ultrafiltration, and nanofiltration, reverse osmosis is the most effective, blocking 99.9% of materials, including monovalent ions, multivalent irons, viruses, bacteria and suspended soils.This approach is better for the environment for three reasons:
- Rather than relying on chemicals to clean the water, reverse osmosis uses high-pressure water and electricity to do the process.
- Although chemicals are also used in reverse osmosis equipment, the quantities are low, and the products are not hazardous.
- It needs very little maintenance because detergents and dispersants are used to support it self-cleaning, ultimately extending its service lifetime.
- On average, the life of a membrane is about 3 to 5 years, but this greatly depends on its correct usage.
- Fouling and scaling can reduce the efficiency of reverse osmosis and necessitate frequent membrane replacement, requiring close monitoring of water quality and the use of filter media.
- Reverse osmosis uses osmotic pressure to push water through the membrane which is an energy-intensive process and can drive up environmental impact and operational costs.
- This process produces a concentrated brine of rejected containments and high-concentrated salts which are difficult to dispose of.
- The membranes themselves will also have to be disposed of, ultimately generating waste.
Ion exchange resins in water treatment
Ion exchange is the process of softening and removing unwanted ions from water by exchanging them with another ionic substance. This process aims to purify the water with less chemicals than other approaches and can run continuously, making it an effective and efficient approach to water treatment.This approach has clear benefits, including:
- Ion exchange resins are designed to selectively remove specific ions from water based on their chemical properties, allowing the targeting of specific contaminants.
- It can be integrated with current water treatment processes both as a pre-treatment and as a polishing step to enhance the water quality.
- There is a possibility to regenerate the resins, restoring the resin's capacity for further use and reducing the operation cost and waste generated.
- Their life can easily reach 5 years, and in some cases up to 7 or 8 years, depending on their correct use.
Aside from these, there are a few challenges this approach brings, including:
- The design of the ion exchange system requires an analysis of the resin bed depth, flow rate, contact time and regeneration cycles, and scaling this up would require a new analysis.
- Fluctuations in pH, temperature or the presence of different contaminants can impact the performance of the resins and impact the water quality.
- The resins must be continuously monitored, and water treatment professionals must be ready to quickly take corrective actions to not compromise the resins.
- Like membranes, resins are also damaged by chlorine, which continues to be one of the most widely used industrial biocides.
Combination of the two
Both reverse osmosis and ion exchange are strong approaches individually, but when combined they are extremely effective in water treatment.When starting with the ion exchange, the ion exchange resins serve as osmosis protection, cleaning and removing the contaminants that can foul or scale the reverse osmosis membranes and making the pre-treated water more suitable for the reverse osmosis process.
After the water has been treated, the ion exchange resins can then be deployed into the left-over reverse osmosis concentrate stream, removing specific ions, such as metals or other residual contaminants before further treatment or disposal. The resins can also be applied as a polishing step, removing the dissolved ions or organic compounds that reverse osmosis may not have captured.
In some cases, special resins can be regenerated with the rejection of osmosis, meaning a saving in chemical products. They can also be used to reduce silica at the inflow, which is difficult and expensive to treat using chemicals, resulting in an increase of up to 50% in permeate recovery, a similar percentage in reject production and less silica fouling. It is also possible to significantly reduce membrane fouling by colloids and organic matter, reduce chemical application costs and operate at a higher flow rate, increasing treated water production.
Lastly, because reverse osmosis often lowers the pH because of the removal of alkaline minerals, ion exchange resins can be added to balance the pH and maintain the desired range for the treated waters.
As you can see, using a combination of ion resin exchange and reverse osmosis overcomes many of the challenges we outlined before. And when they are combined, they can maximize contaminant removal while minimizing operational costs and energy consumption.
Water pre-treatment
Pre-treatment is the process of cleaning the water to improve the water’s characteristics from the start. By doing this, we rely less on chemicals throughout the process and can better reuse or dispose of the wastewater after its use.Various technologies can be employed for pre-treatment, including reverse osmosis and ion exchange, either separately or in combination to achieve greater efficiency. This approach is used today for process water used in the product manufacturing process and to improve the quality of water in boilers, where it is essential to use high-quality water. And although this approach is widely known, it will become more and more relevant with the topics of reusing and reducing water consumption skyrocketing to the top of sustainability agendas around the globe.
While the four methods we’ve discussed today are seen as the future of water treatment, the industry still has a way to go before this is fully integrated into everyday standards. Additionally, it’s important to note that the use of chemicals in water treatment is far from disappearing. Rather, we see the industry moving more towards the use of more biodegradable and sustainable solutions.
Want more? Download our recent whitepaper exploring the key challenges the water treatment industry faces today and the sustainable opportunities that lie ahead. And if you’re interested to learn more about our product portfolio, reach out to our experts today. We offer a wide range of high-quality, top-performing membrane treatments, resins, and much more and are here to help.
