1、 Daily maintenance steps
The daily maintenance of sanitary grade microporous membrane filters is the key to ensuring their long-term stable operation. The filtration device should be disassembled immediately after each use, and the filter membrane should be carefully removed to avoid damage, as damaged membranes may retain microorganisms, affecting the accuracy of subsequent testing and not conducive to equipment cleaning. Gently pick up the filter membrane with tweezers and place it in a suitable waste container for disposal according to laboratory biological waste disposal standards.
For components such as the filter cup, filter head, and base of the filter, rinse off visible impurities and residual culture medium on the surface with clean water first. When flushing, be careful not to let the water flow be too turbulent to prevent damage to the sealing structure at the interface of the components. After initial removal of impurities by rinsing with clean water, disinfection treatment is required to kill any residual microorganisms. You can choose a suitable disinfectant, such as a 75% ethanol solution, and soak the filter cup, filter head, and base in the ethanol solution for at least 30 minutes to ensure that the surfaces of each component are fully in contact with the disinfectant.
2、 Cleaning and disinfection techniques
There are multiple cleaning methods for microporous membrane filters, including compressed air blowback or chemical cleaning maintenance. Special attention should be paid to controlling the pressure not exceeding 0.15MPa during steam sterilization to avoid damaging the filter membrane structure. According to the type and material of the membrane, suitable cleaning agents should be selected. For example, Omega ultrafiltration membrane packs can use 0.1-0.5M NaOH, while Supor microfiltration membrane packs can use 0.1M Acetic Acid, etc.
The cleaning process should follow specific steps: first, use a sample compatible buffer to rinse in the mode of upstream rinse downstream rinse circulating rinse emptying, and rinse at least 3 minimum operating volume solutions. Then perform upstream cleaning, close the permeate end, fully open the reflux end, and cycle to rinse the upstream of the membrane under conditions greater than the tangential flow rate of the process. 1-3 solutions with the minimum operating volume can be used, cycled for 5-10 minutes, cycled 2-3 times, and finally emptied.
3、 Filter membrane replacement cycle and precautions
The replacement cycle of microporous membrane depends on the frequency of use and water quality. It is usually recommended to replace it every 3-6 months, but in cases of poor water quality or high water consumption, it may need to be shortened to 3 months. When replacing the filter membrane, the first step is to turn off the power or water source of the equipment, and wait for the equipment to completely stop running before proceeding with the operation, to avoid forced shutdown that may cause the filter membrane to rupture.
When replacing, special attention should be paid to the following points: ensure that the installation direction is correct, most filters have flow direction markings (such as arrows), and reverse installation can cause filter failure or equipment damage; Check if the sealing ring is intact, and replace it promptly if it is damaged; The correct model of filter membrane must be selected. Using non original or non matching filters may result in installation failure or decreased filtration efficiency. The replaced old filter element contains pollutants and should be disposed of according to regulations to avoid environmental pollution.
4、 Daily use and maintenance skills
In daily use, frequent starting and stopping of equipment should be avoided. When not using water for a short period of time (such as within 30 minutes), it is not necessary to turn off the water purifier. Frequent switching can cause pressure fluctuations in the filter element and accelerate the aging of the sealing ring. If the local water quality is hard or the sediment content is high, it is recommended to install a pre filter (such as PP cotton or stainless steel filter screen) to intercept large particle impurities and reduce the burden on the main filter element.
Controlling water temperature and pressure is also important: the inlet temperature of the water purifier is usually 5-40 ℃, avoiding direct connection to hot water; Install a water pressure gauge to ensure that the inlet pressure is between 0.1-0.4MPa (approximately 1-4 kilograms). If it is too high, a pressure reducing valve should be installed, while if it is too low, it may affect the outlet flow rate. Regularly inspect the appearance of the equipment for physical damage, dust accumulation, or foreign objects blocking the air outlet, and promptly address any issues found.
5、 Precautions for use
When using a microporous membrane filter, special attention should be paid to the following points: control the filtration pressure to avoid exceeding the capacity of the membrane; Proper pretreatment of samples, especially fluids containing a large amount of suspended solids; Ensure that the pore size of the filter membrane is suitable for the substance to be filtered; Strictly prevent pollution during the operation process.
When filtering liquids, the filter membrane must be in a wet state. If the filter membrane becomes dry due to disinfection, it must be wetted with sterile water. Poor wetting can affect the flow rate. Before sterilization filtration, all equipment filter membranes must be disinfected, and then sterilization filtration should be carried out in a sterile room, strictly following the sterilization operation procedures. In addition, filter membranes of different materials have varying tolerances to chemical substances, and it is necessary to understand whether the filtering substances have an impact on the membrane before use.