Application of Microwave/Electrodeless Discharge Ultraviolet/Ozone Sterilization Technology in Water Reclamation

Abstract

In recent years, a new water treatment technology based on microwave discharge electrodeless lamp (MDEL) has been developed. Hence, we designed an integrated system of microwave/electrodeless discharge ultraviolet/ozone (MW/UV/O3) for sewage sterilization according to the theoretical study of MDEL. The experiment was designed to test the ability to sterilize Escherichia coli and Bacillus subtilis by using different process conditions, such as single O3, MW/UV and MW/UV/O3, aiming to find an optimal process route. The results showed that the bactericidal effect of MW was mainly thermal effect, the bactericidal effect of MW/UV was significantly affected by turbidity, while the bactericidal effect of MW/UV/O3 was better than single O3 and MW/UV. In the dynamic test, when the four electrodeless UV lamps were stable, the light intensity reached 3.6mW/cm2; when the aeration rate was 50L/min, the generated O3 content was 0.30mg/L. With a water flow of 800L/h and hydraulic retention time of 1.5min, a sewage sterilization rate of >99.99% was achieved by MW/UV/O3 system, and other water quality indexes including chemical oxygen demand (COD) and total organic carbon (TOC) in effluents was also decreased to some extents.