Ultrafiltration is a technology that simultaneously concentrates and separates large molecules or colloidal substances. Driven by the pressure difference, when the liquid flows on the surface of the ultrafiltration membrane, large molecules or colloidal substances are trapped, and small molecules and pure water pass through the membrane. The pore size of the ultrafiltration membrane for water treatment is roughly between 0.01-0.1um. According to different material, ultrafiltration membrane generally are divided into PVC Ultrafiltration Membrane, PAN Ultrafiltration Membrane, PVDF Ultrafiltration Membrane, PS Ultrafiltration Membrane.
Before starting the ultrafiltration system, you should first check that the following requirements meet the operating standards: 1. The ultrafiltration pretreatment system is operating normally, and the ultrafiltration water intake comply with the design requirement; 2. The drainage system is ready; 3. PLC program has been input as required; 4. The circuit system check has been completed and the pump is operating normally; 5. The pipe system is connected and cleaned.
After completing the pre-startup inspection of ultrafiltration system, start the ultrafiltration system according to the following steps: 1. Start the raw water pump; 2. Filling and flushing of the ultrafiltration system; 3. Set and adjust the inlet water pressure and the system’s water production; 4. Start the backwash pump, set and adjust the backwash pressure; 5. Set and adjust the intake pressure; 6. Set and adjust chain alarm points; 7. Set the backwash time interval; 8. Set the interval of air scrubbing time; 9. Set backwashing sequence of parallel device. The following form are for your reference:
| Ultrafiltration System Interlock and Alarm | ||
| 1 | Set Point | Inlet pressure of ultrafiltration system is too high |
| Set Value | Normal inlet pressure + 1.0bar | |
| Chain Content | Activate the alarm and the system goes to the state to be started | |
| Chain Delay | The alarm is activated after a delay of 5 seconds, and the system switches to the standby state in 10 seconds | |
| 2 | Set Point | Outlet pressure of ultrafiltration system is too high |
| Set Value | Normal outlet pressure + 0.5bar | |
| Chain Content | Activate the alarm and the system goes to the state to be started | |
| Chain Delay | The alarm is activated after a delay of 5 seconds, and the system switches to the standby state in 10 seconds | |
| 3 | Set Point | Sodium hypochlorite dosing tank level is too low |
| Set Value | The minimum distance from the bottom of the container is 7cm | |
| Chain Content | Activate the alarm, shut down the metering pump, the operator adds sodium hypochlorite solution to the dosing box | |
| Chain Period | The ultrafiltration system is in working condition | |
In order to prolong the service life of the ultrafiltration system, daily maintenance is essential, such as checking the temperature of the centrifugal pump and motor, and whether the water pump, valves, pipes and components of the ultrafiltration system are water leaking or air leaking. The following system failure analysis table are for your review:
| Phenomenon | Possible Reason | Corrective Measures |
| Ultrafiltration membrane pressure difference is too high | Ultrafiltration membrane module is contaminated | Identify the cause of pollution, take corresponding cleaning methods, adjust cleaning parameters |
| Water flow is too high | Adjust the flow according to the requirements in the operation guide | |
| Inlet water temperature is too low | Increase the inlet water temperature | |
| Low water production flow | Ultrafiltration membrane module is contaminated | Identify the cause of pollution, take corresponding cleaning methods, adjust cleaning parameters |
| Incorrect valve opening setting | Check and ensure that all valves that should be opened are in the open state, and adjust the valve opening | |
| Flow meter problem | Check the flow meter to ensure normal working status | |
| Water supply pressure is too low | Check the water inlet pressure and adjust the pressure to meet the operating standard | |
| Inlet water temperature is too low | Increase the inlet water temperature | |
| Poor water quality | Inlet water quality exceeds the allowable range | Check incoming water quality, mainly turbidity, COD |
| The membrane module is damaged | Find the cause of damage, repair or replace the membrane module | |
| The system cannot run in the automatic state | Water supply pump does not start | Eliminate the possibility of wiring error, restart the pump in the manual state, and switch to automatic control after normal operation |
| Inlet pressure is too high | Check the water pump and pressure switch settings | |
| High product water back pressure | The product water outlet valve is not opened, the subsequent system is not started in time, and the pressure switch setting problem | |
| PLC program error | Check the program |
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