- 2025-07-22
Removal of E. coli from water
Characteristics and risks of Escherichia coli
Toxigenic strains: Shiga toxin-producing strains such as O157:H7
Infection threshold: ≥100 CFU/100mL (GB 5749 mandatory limit)
Transmission route: surface water/shallow groundwater contaminated by feces
Key technical measures
Multi-stage barrier system
Membrane filtration guarantee
Reverse osmosis device (retention rate>99.99%, membrane pore size≤0.0001μm)
Nanofiltration pretreatment (200-500Da molecular weight cutoff)
Ultraviolet disinfection system
Dose control: 40mJ/cm² (inactivation rate 4-log)
Quartz sleeve transmittance>85%
Chemical enhancement scheme
Chlorine contact disinfection (CT value ≥15mg·min/L)
Chlorine dioxide addition (residual amount 0.1-0.8mg/L)
Key points of project implementation
Water source protection:
Groundwater wells are set with a 50m protection radius
10 upstream of the surface water intake 00m no-discharge zone
System redundancy design:
Ultraviolet or chlorine disinfection secondary protection must be configured after the membrane process
Ultraviolet intensity sensor real-time monitoring (alarm threshold 70%)
Treatment efficiency verification
Microbial detection:
Enzyme substrate method (24-hour rapid quantification)
Daily monitoring of total coliform group & heat-resistant coliform group
Membrane integrity detection:
Pressure decay test (△P <10%/min)
Laser particle counter online monitoring
Operation advantage analysis
Ultraviolet system:
No disinfection by-products (avoid chloroform generation)
Operation cost <0.03 yuan/ton (100m³/h scale)
Combined process guarantee:
Maintain biosafety in sudden pollution events
Membrane system and ultraviolet light synergistically achieve 6-log removal rate