Wastewater Treatment: Demineralisation or Deionisation
Industrial and commercial processes produce large quantities of wastewater. This requires prior treatment before discharging into the municipal drainage system or the environment, in accordance with the Environmental Agency in the United Kingdom. Different wastewater treatment solution systems are available to reduce contaminants, toxins, and impurities of different types in order to maintain the safety levels and standards.
Examples of toxins found in industrial liquid waste include chemicals, pesticides, oils, heavy metals, pharmaceuticals, and other industrial by-products. Among the popular purification methods employed by reputable companies in industrial liquid waste treatment are demineralisation and deionisation - both of which employ ion exchange processes. Though used interchangeably, these methods are different.
Ion Exchange
This is a wastewater treatment solution that involves removing ions from contaminated industrial water by exchanging them with less harmful ones of similar charge, using resin beds. Contaminated water is forced through the resin beds under high pressure, where the exchange process takes place. The positive ions (cations) of the resins will bind negative ions (anions), and vice versa, to achieve purified liquid waste with fewer toxins. This can be discharged or reused, while water with high levels of displaced ions is collected and treated before disposal.
Over time, the effectiveness of resin beds decreases due to the high content of ions from the purification process, which requires renewal. This renewal process is called regeneration, where toxic ions are removed by replacing them with new ions. This process is effective in removing calcium, magnesium, certain organic contaminants, heavy metals, nitrate, arsenic, sulphate, and fluoride.
What is Demineralisation?
Demineralisation is a process of removing minerals by various methods, such as ion exchange, reverse osmosis (RO), and others. However, this wastewater treatment solution has been restricted to ion exchange; hence, it is used interchangeably with deionisation.
Reverse osmosis uses pressure higher than the osmotic pressure to force water through a semipermeable membrane, where up to 99% of toxins and impurities are trapped on the membrane while water passes through. Purified wastewater, called permeate, has fewer toxins, while brine or unfiltered wastewater is stored for further purification.
Deionisation
Deionisation solely relies on the ion exchange process to remove cations and anions from contaminated liquid waste. Typical cations include calcium, magnesium, and iron, while anions include sulphate, nitrate and carbonates.
Similarities and differences
- These wastewater treatment solution methods utilise an ion exchange process in a deioniser plant; however, demineralisation also includes other processes such as reverse osmosis.
- When focusing only on the ion exchange process, they refer to the same thing.
They both remove ions and minerals; however, other methods of demineralisation may not be effective at removing some ions, especially those with smaller sizes.
Products Used in These Systems
Various products employ ion exchange systems, and they are as follows:
- Short-cycle demineraliser units: Units that undergo regeneration for a period ranging between two to two and a half hours. Some units only require 30 minutes.
- Counter-current demineraliser units: Employ a technique where the chemical used to rejuvenate the resin beds or the regenerant chemical is supplied in the direction opposite to service flow.
- Counter-current demineraliser units: Employ a technique where the chemical used to rejuvenate the resin beds or the regenerant chemical is supplied in the direction opposite to service flow.
- Multiport valve technology: To facilitate easy operations, multiport valves are installed in treatment plants to allow multiple functions and settings within a single valve body. These are typically found in smaller-sized plants.
- Diaphragm valve: Used in larger plants to control the flow of chemicals, sludges, and other fluids and to allow easy access for servicing and maintenance.
Deionisation and demineralisation are viable industrial wastewater treatment solutions effective in the removal of minerals and ions. They produce purified wastewater that meets the required environmental standards. For a system that is appropriate to your unique industrial and commercial needs, it is important to consult a reputable and experienced professional to install and maintain a waste treatment system.
Deionisation and demineralisation are viable industrial wastewater treatment solutions effective in the removal of minerals and ions. They produce purified wastewater that meets the required environmental standards. For a system that is appropriate to your unique industrial and commercial needs, it is important to consult a reputable and experienced professional to install and maintain a waste treatment system.
