## 2 Materials and Methods
### Photolytic and Photocatalytic Treatments
#### 2.2.3 Degradation Treatments for Pesticides and Microorganisms in Aqueous Solutions  
A lab-scale reactor was used to investigate the effects of the UV light source and the presence of TiO\({}_{2}\) photocatalyst on degradation of pesticides and microorganisms in aqueous solutions. The reactor consisted of a stainless-steel cylindrical vessel with an effective volume of 4.0 L. Two types of low-pressure mercury lamps were used to provide UVC and VUV irradiation. A UVC lamp capable of emitting light of a wavelength of 254 nm (35 W, 25 mW/cm\({}^{2}\), Sankyo Denki, Japan) and a VUV lamp emitting at both 254 nm and 185 nm (35 W, 25 mW/cm\({}^{2}\), Sankyo Denki, Japan) were used. The lamps were placed in the center of the reactor with quartz tube protection. A TiO\({}_{2}\)-coated quartz tube (38 cm length, 24.5 mm outer diameter; TiO\({}_{2}\) coating thickness 0.7-0.9 mm; Taekyeong UV Co., Namyangju, Korea) was used for photocatalytic treatments, and an uncoated quartz tube was used for photolytic treatments. Four photolytic and photocatalytic treatments were applied: (i) UVC (254 nm) photolytic  
Figure 1: Experimental flow charts. (**a**) experiments to investigate the effect of the UV light source and TiO\({}_{2}\) photocatalysis on degradation of pesticides and microorganisms. (**b**) Experiments to investigate the effects of mixture compounds and aeration condition on the degradation efficiency of pesticides cocktail under VUV-TiO\({}_{2}\). (**c**) Experiments to investigate the removal effect of residual pesticide and microorganisms from carrot samples.  
treatment, (ii) VUV (254 nm and 185 nm) photolytic treatment, (iii) UVC-assisted TiO2 photocatalytic treatment (UVC-TiO2), and (iv) VUV-TiO2 photocatalytic treatment (VUV-TiO2).  
An experiment was conducted in order to investigate mixture (or multi-component) effect on degradation efficiency. The degradation efficiency of each active compound in a cocktail solution (5 ppm of each active compound, corresponding 20 ppm of total active compounds) was compared to a single pesticide solution containing 20 ppm of each pesticide under VUV-TiO2 (Figure 1).  
Another experiment was conducted to investigate the effect of aeration under VUV-TiO2 on the degradation of pesticides in a cocktail solution. This aeration was produced while using a magnetic stirrer only (no aeration), an air injector with magnetic stirring at 300 rpm (mild aeration) (SH-A2 bubble generator, Zhongshan Canhu Electric Factory, Zhongshan, China), and an air compressor with magnetic stirring (extra aeration) (2522C-10, Welch, Concord, MA, USA). Under mild aeration, air was supplied to the vessel through a silicone tube at a flow rate of 1.8 L/min. In extra aeration, compressed air was introduced through the micropore mesh plate installed at the bottom of the vessel at a flow rate of approximately 20 L/min. During photolytic and the photocatalytic treatments, 10 mL aliquots were taken for HPLC analysis at treatment times of 30, 60, 120, and 180 min.  
Microbial inactivation experiments were conducted under UVC, VUV, UVC-TiO2, and VUV-TiO2 treatments (Figure 1). Briefly, each liquid culture of _E. coli_ K12 and _Saccharomyces cerevisiae_ was added to a sterile 0.85% NaCl solution in the lab-scale reactor. The total treated volume of microbial culture was 4 L. Liquid samples of approximately 10 mL were withdrawn from the reactor at 30 s intervals for up to 120 s.  
Photolytic and Photocatalytic Treatments for Residual Pesticides and Microorganisms on Fresh Cut Carrots