What Water Treatment Equipment Is Needed For Desalination And Water Production?

In many industrial and commercial applications, high-purity water is of utmost importance. For example, in the semiconductor manufacturing industry, even the slightest impurity in water can affect the performance of microchips. In the pharmaceutical industry, high-quality water is crucial for drug production to ensure the safety and efficacy of medications. Desalination and water production processes require a series of sophisticated water treatment equipment to remove various impurities and minerals from raw water.​

One of the key pieces of equipment in desalination and water production is the Reverse Osmosis (RO) equipment. RO is a membrane separation technology that uses a semi-permeable membrane. Under the action of external pressure, water molecules can pass through the membrane, while most ions, colloidal substances, and large-molecular organic matter are intercepted. The basic principle is based on the fact that the semi-permeable membrane has a selective permeability, allowing water to pass through while blocking salts. Also, the external pressure applied to the saltwater side is greater than the osmotic pressure between the saltwater and freshwater sides, providing the driving force for water to move from the saltwater side to the freshwater side. RO equipment is widely used as it can effectively remove a large number of impurities, reducing the Total Dissolved Solids (TDS) in water and significantly lightening the load on subsequent desalination equipment.

Another important water treatment equipment is the Electrodeionization (EDI) device. EDI combines electrodialysis technology and ion-exchange technology. It uses cation-exchange membranes and anion-exchange membranes, along with ion-exchange resins. Under the action of an electric field, cations in water move towards the negative electrode through the cation-exchange membrane, and anions move towards the positive electrode through the anion-exchange membrane. At the same time, the ion-exchange resins in the device continuously exchange and adsorb ions in water, achieving deep desalination of water. EDI has the advantage of continuous operation without the need for chemical regeneration using acids and alkalis, which not only simplifies the operation process but also reduces environmental pollution. It can produce high-purity water with a resistivity of up to 16-18 MΩ·cm, meeting the strict water quality requirements of high-tech industries.​

In addition to RO and EDI, there are also multi-media filters in the water treatment system. These filters are filled with different media such as quartz sand, anthracite, and activated carbon. Their function is to filter out larger-sized suspended solids, particles, and some organic matter in the water through physical filtration and adsorption. The multi-media filter is usually used as a pre-treatment device to protect the more sensitive subsequent treatment equipment such as RO membranes from being blocked by large particles, thereby extending the service life of the equipment.

Cation-exchange resin columns and anion-exchange resin columns are also essential components. Cation-exchange resins exchange their hydrogen ions with metal cations in water, while anion-exchange resins exchange their hydroxide ions with anions in water. By using these two types of resin columns in combination, most of the ions in water can be removed, further purifying the water quality. For example, in a traditional ion-exchange water treatment system, water first passes through the cation-exchange resin column, then through the anion-exchange resin column, and finally through a mixed-bed resin column for further purification.​

Moreover, ultrafiltration equipment is also commonly used. Ultrafiltration uses ultrafiltration membranes with different pore sizes to filter out suspended solids, colloids, bacteria, and some macromolecular organic matter in water. The pore size of ultrafiltration membranes is generally in the range of 0.001-0.1 micrometers. It can effectively remove impurities that are larger than the pore size of the membrane while allowing water molecules and some small-molecular substances to pass through, playing an important role in pre-treatment and post-treatment of water.​

In conclusion, the desalination and water production process requires a combination of various water treatment equipment, including Reverse Osmosis equipment, Electrodeionization devices, multi-media filters, cation- and anion-exchange resin columns, and ultrafiltration equipment. Each piece of equipment has its unique function and advantage, and they work together to produce high-quality water that meets different industrial and commercial needs. With the continuous development of technology, these water treatment equipment are also constantly being improved and innovated to provide more efficient and sustainable water treatment solutions.