Efficiency improvement of batch reactors for water sterilization using UV-C LED arrays

Area of Science:

• Environmental Microbiology
• Photochemistry
• Water Treatment Engineering

Background:

• UV-C light emitting diode (LED) technology presents advantages over traditional mercury lamps for water sterilization.
• Effective bacterial inactivation requires sufficient UV fluence, making LED array arrangement critical due to their point light source characteristics.

Purpose of the Study:

• To investigate the inactivation of Escherichia coli (E. coli) using a 280 nm UV-C LED array.
• To analyze the impact of input electrical power, chip interspace (L), and reactor-to-water distance (D) on E. coli inactivation efficiency.

Main Methods:

• Utilized a multi-chip UV-C LED array (280 nm) for E. coli inactivation experiments.
• Systematically varied input power, chip interspace (L), and distance (D) to assess their effects.
• Quantified E. coli log inactivation without the use of a magnetic stirrer.

Main Results:

• Achieved optimal E. coli inactivation of 4.0 log at L = D = 25 mm.
• Observed a decrease in the rate of log inactivation with increasing input power.
• Identified reduced wall plug efficiency of UV-C LEDs at higher input powers as a contributing factor.

Conclusions:

• Optimized UV-C LED array configuration (L=D=25 mm) effectively inactivates E. coli in water.
• Input power and LED arrangement significantly influence UV-C disinfection efficiency.
• Wall plug efficiency considerations are crucial for optimizing UV-C LED water treatment systems.