## Materials and Methods
### Experimental Operation  
Three phases of the experiment were conducted to achieve three established objectives. In the first phase, the experiments were performed in a sequence to investigate the feasibility of CW for treating water containing varying initial organic concentrations. In the next step, the investigation of treatment efficiency of CW in different HRT conditions was also carried out in turn. The scheme was presented in Figure 3.  
The volume of 6 L containing synthetic water prepared by adding HA stock solution into raw water was pumped from the influent tank into bench-scale CW. Two peristaltic pumps were used to pump water continuously from influent tank to wetland and from wetland to effluent tank. CW was operated in turn with three different input organic concentrations, including 3.0-4.5 mg/L, 4.5-6.0 mg/L and 10-12 mg/L (named run 1, 2 and 3, respectively), with the HRT was fixed at 1 day, flow rate was 3.47 mL/min. The water level in CW was maintained in the height of 30 mm above the mixture of sand and soil layer. Samples were collected daily from the influent and the effluent of CWs, where S\({}_{i}\), S\({}_{i}\) representing influent and effluent samples, respectively. Collected samples were analyzed with the following parameters: pH, alkalinity, ultraviolet absorbance at 254 nm (UV-254), DOC, sCOD, ammonia nitrogen (NH\({}_{3}\)-N) and nitrate (NO\({}_{3}\)-N). Only samples for analyzing DOC were stored in the fridge at 4 \({}^{\circ}\)C for a maximum of 1 week, the others were analyzed immediately after daily collecting. In terms of investigating effects of the change of HRTs, CW was run under the conditions of fixed DOC concentration influent at 10-12 mg/L and 1 day-HRT and 2 day-HRT (named run 3 and  
Figure 3: Layout of prototype of bench-scale constructed wetland: (**1**) Influent tank; (**2**) Peristaltic pump; (**3**) Influent pipe; (**4**) Constructed wetland; (**5**) Mixture sand and soil; (**6**) Gravel; (**7**) Baffle; (**8**) Plants; (**9**) Effluent pipe; (**10**) Effluent tank. Figure 2: The layout of the photocatalytic reactor. 4, respectively). The flow rate of each pump was set according to different HRTs, 3.47 mL/min and 1.74 mL/min with 1 day-HRT and 2 day-HRT, respectively. Regarding the second phase, with the aim to evaluate the removal efficiency of TC in water by using only CW system for treatment, phase 2 of this study was conducted under the condition of HRT-1 day, flow rate was set up 3.47 mL/min and with different initial TC concentrations, 1 mg/L, 5 mg/L and 10 mg/L. The procedure to operate CW in this phase was mostly similar to that in phase 1. However, the influent was made different, synthetic water in this phase was prepared by adding TC stock solution with various dosages into raw water. Monitored parameters in phase 2 were pH and TC concentration. One important thing in this phase is that during the experiments, the influent tank was covered with aluminium foil to obstruct sunlight, to prevent photolysis of TC because TC can be easily degraded under the light. Samples from the influent and the effluent were collected daily in clean brown glass vials and frozen until analysis. In addition, during the first days after periods of 2, 4, 6, 12 and 24 h of operation, samples were taken to examine the change of TC concentration during the periodic time in 1 day. In the final phase, the experiment was conducted with the combination of CW and PCR to examine the feasibility of this combined system in treating water with initial DOC concentration ranging from 10 mg/L to 12 mg/L. The combination was operated in sequence, CW was considered as a pre-treatment system, PCR played the role of a post-treatment process. The flow rate was controlled at 3.47 mL/min, corresponding to effective volumes (5 L and 0.8 L) and HRTs (1 day and 3.84 h) for CW and PCR, respectively. The amount of TiO\({}_{2}\)/\(\alpha\)-Al\({}_{2}\)O\({}_{3}\) used in PCR was 20 g. The water level in CW still remained at 30 mm above the substrate layers and the height of water in the PCR was 95 mm.