Method and principle of sewage treatment

When the salt removal rate of seawater requires the reduction of NaCl from 35,000 mg/L to 500mg/L, the salt removal rate is required to be as high as 98.6%. If the first level is not reached, it can be divided into two steps. That is, 90% of NaCl is removed in the first step, and 89% of NaCl is removed from the water in the second step, which can meet the requirements. If the salt removal rate of the membrane is low, and the water permeability is high, the two-step method is more economical, and the service life of the membrane can be improved when it is operated under low pressure and low concentration.

In this process, the first level of concentrated liquid is used as the feed liquid of the second level, and the second level of concentrated liquid is used as the feed liquid of the next level, at this time, because all levels of water are directly discharged to the body, so with the increase of the water recovery rate, the volume of concentrated liquid is reduced and the concentration is increased. In order to ensure a certain flow rate of the liquid and control the concentration polarization, the number of membrane components should be gradually reduced.

ultrafiltration

Ultrafiltration is similar to reverse osmosis in that it also uses a semi-permeable membrane, but it cannot control the removal of ions due to the large pore size of the membrane, about 10-200A. Only bacteria, viruses, pyrogen and particles can be excluded, and water-soluble ions cannot be filtered. The main function of the ultrafiltration process is to act as a pre-treatment of the reverse osmosis process to prevent the reverse osmosis membrane from being contaminated by bacteria. It can also be used in the final step of water treatment to prevent upstream water from being contaminated by bacteria in the pipeline. Generally, the difference between the inlet water pressure and the outlet water pressure is used to determine whether the ultrafiltration membrane is effective, similar to activated carbon, usually the backwash method is used to remove impurities attached to it.

Distillation method

Distillation is an ancient but also effective water treatment method, it can remove any non-volatile impurities, but can not exclude volatile pollutants, it requires a large storage tank to store, the storage tank and the transmission pipe is an important cause of pollution, hemodialysis water does not need to be treated in this way.

Ultraviolet disinfection

Its bactericidal mechanism is to destroy the life genetic material of bacterial nucleic acid, so that it cannot reproduce, and the most important reaction is that the pyrimidine base within the nucleic acid molecule becomes dimer. It is generally the use of low pressure mercury discharge lamps (germicidal lamps) artificial 253.7nm wavelength of ultraviolet energy. The principle of the ultraviolet germicidal lamp is the same as that of the fluorescent lamp, but the lamp tube is not coated with fluorescent substances, and the material of the lamp tube is quartz glass with high ultraviolet penetration. The general ultraviolet device is divided into irradiation type, soaking type and running type according to the use.

The ultraviolet light used in hemodialysis dilution water is placed on the pipe between the storage tank and the dialysis machine, that is, all dialysis water must be irradiated with ultraviolet light before use to achieve complete sterilization. Pyo and coliform bacteria were the most sensitive to ultraviolet light. In contrast, subtilis spores were more tolerant. Because UV disinfection is safe, economical, less selective to strains, and the water quality does not change, this method has been widely used, such as drinking water on ships. The Igora bacteria in the water, Basra bacteria, Salmonella and so on all killed, can dive into the center of the water 360 degrees sterilization, the effect is equal to three times the surface sterilization lamp. It can eliminate the algae in the water, the effect is remarkable, easy to use, ultraviolet bactericidal lamp is suitable for: filtration of various sizes of fishing grounds, water treatment, large and small pools, swimming pools, hot springs. The bactericidal efficiency can reach 99%-99.99%.

Ultraviolet water treatment technology - sterilization

Ultraviolet sterilization is mainly the use of 254 nanometer wavelength ultraviolet light. This wavelength of ultraviolet light, even at a tiny dose of ultraviolet radiation, can destroy the core of a cell's life-DNA, thus preventing cell regeneration, loss of regenerative ability to render bacteria harmless, thus achieving sterilization effect. Like all other UV application technologies, the size of the system depends on the intensity of the UV (the intensity and power of the irradiator) and the exposure time (the length of time that water, liquid, or air is exposed to the UV).

Ultraviolet water treatment technology - ozone elimination

In industrial production, ozone is often used to disinfect and purify water bodies. However, due to the strong oxidation capacity of ozone, the remaining ozone in the water may affect the next process if it is not removed, so the remaining ozone in the water must be removed before the ozonated water enters the main process. Ultraviolet light at a wavelength of 254 nanometers is very effective at destroying the remaining ozone, which can be broken down into oxygen. Although the scale required varies from system to system, a typical ozone elimination system typically requires about three times as much UV radiation as a traditional sterilization system.