Zero discharge ultrafiltration reverse osmosis process
In order to achieve the goal of zero discharge of wastewater in power plants, the scientific application of ultrafiltration reverse osmosis technology is particularly important. This technology is mainly to selectively filter the organic matter and particles inside the aqueous solution, so as to achieve a series of functions such as separation and purification, and the driving force of ultrafiltration is mainly to use the pressure difference on both sides of the ultrafiltration membrane.
1, ultrafiltration reverse osmosis process principle and characteristics
Ultrafiltration reverse osmosis system process is relatively simple, mainly including ultrafiltration device and reverse osmosis device, through the use of programmable logic controller, for flocculation filtration and ultrafiltration, including reverse osmosis device for scientific control, can significantly improve the wastewater treatment effect. Compared with the traditional water treatment mode, the industrial pollution index of this treatment is relatively low, and the effluent water quality is more stable, which can effectively improve the permeable flux of the reverse osmosis membrane, and further extend the operating life of the reverse osmosis membrane.
Through the use of reverse osmosis technology, some components of the aqueous solution can be selectively passed under the action of external pressure, so as to achieve the purpose of purification and desalination. At the same time, strengthen the reverse osmosis water treatment, combined with the water quality requirements and water quality characteristics of the effluent, reasonable adjustments can ensure that the sewage meets the requirements of the reuse water standard, truly achieve the goal of zero sewage discharge, constantly reduce ecological environmental pollution, and save a lot of water resources.
2, power plant wastewater water quality characteristics
The sewage inside the power plant contains more suspended substances, and the salt content and temperature are relatively high, and the microbial content is particularly high, because the wastewater contains more silicic acid compounds and bacteria, which will increase the difficulty of water treatment. If the traditional treatment technology is adopted, the sewage treatment effect will be significantly reduced. Therefore, the relevant units should be combined with the characteristics of power plant wastewater water quality, targeted selection of treatment technology.
In addition, the power plant wastewater in the cycle treatment process, will also produce more microbial film and algae, to the membrane treatment device to bring greater pollution, for example, when the power plant wastewater contains more calcium carbonate, combined with the characteristics of the water cycle can be known, in the specific treatment process is particularly prone to precipitation phenomenon, significantly increasing the difficulty of sewage treatment, improve the cost of sewage treatment. Therefore, the use of scientific sewage treatment technology is particularly important.
3, the specific application of ultrafiltration reverse osmosis process
3.1 Clarify the process treatment flow
First of all, the raw water inside the sewage network needs to remove its internal suspended substances, and the suspended substances enter the sewage regulation tank after removal, and the sewage will gradually enter the self-cleaning filter, so that the impurities inside the sewage are completely removed.
Secondly, add an appropriate amount of sodium hypochlorite and flocculant in the sewage treatment process, so that the solid particles inside the wastewater can be quickly flocculated, and the impurities inside the sewage can be completely filtered after the self-cleaning filter.
Finally, the wastewater from the power plant goes into the ultrafiltration system for further treatment.
Because the temperature of the wastewater inside the power plant is relatively high, it will have a certain impact on the flocculation of the flocculant and the stable operation of the ultrafiltration membrane, so before the implementation of ultrafiltration, it is necessary to effectively cool the wastewater. Generally speaking, the cooling of the wastewater in the power plant needs to be treated with a heat exchanger.
Combined with the characteristics of power plant wastewater filtration, it can be learned that in the actual filtration process, macromolecular organic matter and bacteria, including the suspended substances inside the wastewater are all intercepted by the ultrafiltration membrane, which will have a greater impact on the pressure of the ultrafiltration membrane itself, so the relevant personnel need to regularly carry out a comprehensive backwash, in general, the flow rate of the ultrafiltration membrane backwash is about 4 times the water production. After the ultrafiltration treatment, the wastewater will enter the reverse osmosis supply pump, and then enter the security filter in an orderly manner for subsequent filtration to achieve the reverse osmosis treatment goal. In the actual treatment process, the staff can achieve good treatment results by adding a certain amount of scale inhibitor and reducing agent, significantly reducing the PH value of reverse osmosis water, and adding an appropriate amount of sodium hydroxide for effective regulation, and constantly improve the efficiency of power plant wastewater treatment.
3.2 Ultrafiltration operation
Ultrafiltration membrane is a porous membrane, with good screening and separation functions, can carry out a series of processes such as liquid purification, separation and concentration, and play a good role in removing colloids and particles inside the liquid, as well as bacteria and polymer organic matter. However, the quality of raw water and the polymer organic matter in raw water, as well as the inorganic matter content and the flow rate of the feed liquid will affect the final ultrafiltration effect, among which membrane pollution and membrane hole blockage are the most prominent problems. In order to reduce the occurrence of such problems, the power plant should combine the operation characteristics of the water treatment system to effectively remove large-particle size suspended substances in advance. Ensure that the water quality is significantly improved and the resistance of the ultrafiltration membrane is continuously reduced.
In addition, before the power plant wastewater enters the flocculation tank, it needs to use polyaluminum chloride for flocculation treatment and sodium hypochlorite for comprehensive disinfection. Due to the high temperature of the circulating water itself and the fact that it contains more trace organic matter inside, it is easy to breed a large number of microorganisms in the upper part of the membrane. By adding a certain amount of sodium hypochlorite, the occurrence of biological pollution can be reduced. It plays a certain preventive role, so as to better improve the treatment efficiency of ultrafiltration membrane.
After the above treatment, the power plant wastewater is pretreated, and the treatment effect of osmotic fluid can be improved by orderly filtration inside the filter and strengthening the protection of ultrafiltration membrane. At the same time, during the backwashing process of the system, it is necessary to ensure that the backwashing liquid can orderly pass through the membrane and fiber membrane, and then comprehensively remove the particulate matter on the surface of the ultrafiltration membrane, and quickly restore the filterability of the ultrafiltration membrane itself. Generally speaking, the system runs for about 15min before a backwash can be carried out. Although the backwashing method can effectively remove the debris on the surface of the ultrafiltration membrane, the removal effect is poor, so before the operation, the accumulation of impurities on the surface of the ultrafiltration membrane continues to increase, resulting in the pressure difference between the two sides of the ultrafiltration membrane continues to rise, which will seriously affect the membrane flux. In order to avoid the occurrence of pollutant blockage, the relevant personnel need to regularly use hypochlorous acid or citric acid and other cleaning agents for comprehensive cleaning.
By using cleaning agents such as hypochlorous acid or citric acid for cleaning, organic substances on the surface of the ultrafiltration membrane can be completely removed to ensure that the permeability of the ultrafiltration membrane meets the standard requirements. At the same time, in order to comprehensively improve the power plant wastewater treatment effect, it is necessary to strictly control the operating temperature of the ultrafiltration membrane box, the operating temperature should not be lower than 5 ° C, should not exceed 35 ° C, the inlet temperature should not exceed 20 ° C, if the inlet temperature is too high, it will speed up the hydrolysis rate of the ultrafiltration membrane, if the inlet water temperature is too low, it will significantly reduce the flow of ultrafiltration water. By strengthening the ultrafiltration treatment, the suspended substances inside the wastewater of the power plant can be completely removed, so that the wastewater can meet the standard requirements of reverse osmosis treatment, and can better protect the reverse osmosis membrane, and constantly extend the service life of the reverse osmosis membrane.
3.3 Reverse osmosis operation
The so-called reverse osmosis mainly refers to that under a certain pressure, after the reverse osmosis membrane, the solvent in the wastewater of the power plant is not completely separated, because the solvent and natural penetration are completely opposite, so it is called reverse osmosis. Combining with the osmotic pressure of various materials, the goal of purification and concentration can be achieved by appropriately increasing the pressure of reverse osmotic pressure. Reverse osmosis technology belongs to a kind of liquid separation technology, which plays a certain blocking role for dissolved salt, if the diameter of organic matter is more than 100μm, reverse osmosis membrane can still play a good blocking effect.
In order to better improve the reverse osmosis effect, the relevant personnel can take concentrated water reflux mode, by adding an appropriate amount of scale inhibitor and fungicide in the water, can improve the reverse osmosis efficiency, scale inhibitor can significantly reduce the supersaturation of the solution, for the subsequent concentration process generated dirt to play a good preventive effect, to avoid the production of a large number of organic impurities and colloidal impurities. At the same time, before the reverse osmosis treatment, adding a certain amount of sodium bisulfate can play a good protective effect on the reverse osmosis membrane to avoid oxidant damage to the reverse osmosis membrane.
In addition, the water supply temperature will also have a certain impact on the osmotic fluid flow of the reverse osmosis equipment itself, if the water supply temperature is relatively low, the water viscosity will be significantly increased, reducing the osmotic flow. In general, during the reverse osmosis operation, the temperature is controlled between 15 ° C and 40 ° C, which can ensure that the penetration flow meets the standard requirements. At the same time, the relevant personnel should strictly control the desalting rate and water production, and closely observe the operating status of the reverse osmosis membrane, clean it on time, and keep the cleaning time between 2h and 4h each time.
3.4 Processing Result
In the process of treating the circulating sewage of the power plant, by using the ultrafiltration membrane as the pre-treatment stage, the reverse osmosis treatment effect of the power plant wastewater can be effectively improved, reduce environmental pollution, improve the utilization efficiency of water resources, and truly achieve the goal of zero discharge of the power plant wastewater. According to the above analysis, the ultrafiltration treatment of power plant wastewater can significantly reduce the content of organic matter and microorganisms in the wastewater, and the reverse osmosis treatment technology can realize the secondary utilization of power plant wastewater and ensure that the treated power plant wastewater meets the requirements of the recycling water standard.
4. Conclusion
In summary, by analyzing the effectiveness of the specific application of the ultrafiltration reverse osmosis process in the zero-discharge wastewater of the power plant, such as clarifying the process treatment process, strengthening the ultrafiltration operation, reverse osmosis operation, etc., and conducting a comprehensive analysis of the final treatment results, it can ensure that the ultrafiltration reverse osmosis technology is well used and significantly improve the quality and efficiency of the wastewater treatment of the power plant. Truly achieve the goal of zero waste water discharge.
