Why do we use chemicals to treat our water?
People's first reaction can sometimes be, "We use chemicals to treat our water?" It's important to understand that not all chemicals are the same. In water treatment, chemicals are often "innocent" elements like metal salts, ozone, chlorine, chalk, activated carbon, sodium hydroxide, and potassium permanganate that help us improve the chemistry of the water, making it safe for consumption and use.
Water treatment involves various processes to remove contaminants and ensure safety. Here's how these chemicals play a crucial role in this process:
Disinfection: Chemicals like chlorine are used to kill harmful bacteria and viruses, preventing waterborne diseases. This step is vital for protecting public health.
Coagulation and Flocculation: Metal salts, such as iron chloride and aluminum sulfate, help bind small particles together, making them easier to remove. This process clears the water, removing dirt and other particles that can cause cloudiness. Besides, these metal salts can be used to remove heavy metals and phosphate.
pH Control: Chalk (calcium carbonate) and caustic soda (sodium hydroxide) are used to adjust the pH level of water. Maintaining the right pH balance is important for effective treatment and to prevent corrosion in pipes, ensuring the longevity of infrastructure and the safety of the water.
Contaminant Removal: Activated carbon is used to adsorb and remove contaminants like organic micro pollutants, , and nitrates. This step is essential for eliminating harmful substances that can affect health and the environment.
Oxidation: Ozone, hydrogen peroxide, and potassium permanganate are used to oxidize and break down organic materials and pathogens in the water, leaving no residual taste or odor.
Using these chemicals in water treatment is a scientific and controlled process, designed to enhance water quality. These chemicals are carefully selected and managed to ensure they improve the water without causing harm. Through these processes, we ensure that the water we drink and use is clean, safe, and healthy, but also that the water used in our industries and the wastewater they produce is safe to discharge or reuse.
It's important to understand that we are not only talking about drinking water; water treatment is crucial for all types of water use, including industrial processes and wastewater management.
What are metals salts?
Metal salts are essential compounds used in the water treatment process. They consist of a metal element, as iron (Fe) or Aluminum (Al), which is combined with a non-metal element, being the salt (generally chloride or sulphate). Common metal salts used in water treatment include iron chloride (FeCl2 - FeCl3), iron sulphate, aluminum chloride (PAC), and aluminium sulfate. These salts play a crucial role in ensuring water quality and safety.
Metal salts are used to coagulate and flocculate suspended particles in water. They help bind small particles together into larger clumps, making them easier to remove. This process is essential for clarifying water and removing turbidity.
Metal salts are also effective in removing nutrients from the water. They help eliminate phosphates, which can lead to algal blooms in water bodies and deplete oxygen, harming aquatic life. Metal salts also remove heavy metals like lead, mercury, and cadmium, which can be toxic to humans and animals. Additionally, they help to remove hydrogen sulfide, which can produce unpleasant odors and be corrosive, thus improving water quality.
Metal salts are used in various applications, from drinking water production or production of process water for industrial purposes. The majority of metal salts, however, are used in wastewater treatment. Both municipal and industrial wastewater treatments rely on metal salts to remove contaminants such as phosphates and heavy metals, ensuring the treated water is safe to discharge or reuse.
So what is wrong with it?
There is nothing inherently wrong with using metal salts. They are effective and widely used in water treatment for removing impurities and ensuring water quality. However, their use is not without drawbacks.
First, the production of metal salts carries a high carbon footprint. The processes involved in mining, refining, and manufacturing these chemicals are energy-intensive and contribute substantially to greenhouse gas emissions. This environmental impact is a critical concern as industries strive to reduce their carbon footprints and combat climate change.
Second, metal salts introduce unnecessary, and generally unwanted, salts and acids into the water. These substances can alter the pH balance of treated water, making it more acidic. Consequently, additional chemicals are often required to neutralize these acids, further complicating the treatment process and increasing operational costs.
Additionally, the supply chain for metal salts proved to be vulnerable to disruptions. For instance, in 2021, Europe experienced a significant shortage of iron chloride due to a combination of reduced hydrochloric acid production, high energy prices, and logistical challenges exacerbated by the COVID-19 pandemic and import declines from Russia. This disruption highlighted the sector's dependence on external factors and the potential for recurring shortages.
Moreover, the cost of metal salts can be prohibitively high in regions far from production locations. In Africa, for example, the price of metal salts can be up to five times higher than in Europe due to transportation and logistical challenges. This makes water treatment significantly more expensive and less accessible in these areas, underscoring the need for more localized and sustainable solutions.
How it can be different?
The key to revolutionizing water treatment lies in focusing on metal ions, the essential component. Instead of transporting bulky and environmentally harmful metal salts, we can transport raw metal resources and convert them on-site into the required compounds. This process utilizes electrochemical technology to produce the necessary molecules directly at the treatment plant, ensuring efficiency and sustainability.
Using raw metals like steel offers several advantages. Steel is more resilient to supply chain disruptions because it is easier to store and often produced locally. This ensures a consistent supply of necessary compounds, regardless of external market fluctuations.
On-site conversion also minimizes the introduction of unwanted salts and acids into the water, reducing the overall chemical load and environmental impact. By producing only the needed compounds, we simplify the treatment process and avoid the additional chemicals typically required to neutralize the by-products of traditional metal salts.
Embracing on-site conversion transforms water treatment into a more sustainable, cost-effective, and resilient process. This approach meets the immediate needs of water treatment facilities while supporting broader environmental and economic goals, paving the way for a cleaner, more efficient future.
