Textile industries consume large amounts of water and generate large quantities of wastewater daily. Globally, around 700,000 tons of dyes are synthesized, and about 280,000 tons of textile dyes are discharged into water bodies annually. Textile wastewater contains several complex and hazardous materials. Therefore, new, cost effective, and environmentally friendly technologies are needed to treat textile wastewater effluents. This study explores using zinc oxide nanorods (ZnO NRs) as a supported catalyst in the photocatalytic degradation of methylene blue dye as a model contaminant in textile wastewater under natural sunlight irradiation. ZnO NRs catalysts were fabricated on glass substrates using the microwave-assisted hydrothermal method. The characteristics of the synthesized ZnO NRs were investigated by using X-ray diffraction (XRD), photoluminescence (PL), scanning electron microscopy (SEM), and UV-visible spectroscopy. The XRD and SEM results confirmed that the synthesized ZnO NRs have a hexagonal Wurtzite crystal structure. Moreover, the water contact angle of the ZnO NRs surface was conducted to determine the surface wettability. The highest surface wettability of ZnO NRs and physical adsorption was achieved at pH 8. Photocatalytic degradation was conducted with methylene blue (MB) as a contaminant under natural sunlight in a batch system followed by a continuous flow reactor. In the batch reactor, three different concentrations of MB were examined under simulated and natural sunlight. MB degradation reached 100%, 48%, and 52% of MB under simulated sunlight and 100 %, 83 %, and 62 % under natural sunlight for 10, 50, and 100 ppm, respectively, after 3 hours of irradiation. The continuous flow reactor showed higher degradation efficiency, especially at a low flow rate. This is because of the high residence that leads to long time of interaction between MB molecules and the surface of ZnO NRs catalyst. Methylene blue degradation was 80 %, 67 %, 58 %, and 46 % at flow rates of 1.5, 2.5, 4.5, and 6 ml/min, respectively. MB's photocatalytic degradation followed a pseudo-first-order Langmuir-Hinshelwood kinetic model. Furthermore, five single-channel continuous flow reactors were connected in series to emulate the properties of a multi-channel flow reactor, and the photocatalytic efficiency reached 26 %, 44 %, 63 %, 85 %, and 90 % after passing through the first, second, third, fourth and fifth flow channel, respectively. The concentration of the final test solution was reduced from 100 ppm to 11 ppm after passing the five single-channel serpentine flow reactors. Regarding the reusability test of the used ZnO NRs, the degradation efficiency of MB decreased from 80.1% in the first cycle to 45 % after five consecutive cycles due to the accumulation of the MB molecules in the surface of the ZnO NRs. The used ZnO NRs were cleaned by dipping them in DI for 30 minutes under natural sunlight to improve the reusability of ZnO NRs for MB removal. The cleaning of used ZnO NRs for 30 minutes achieved a stable catalyst surface with good experimental repeatability. SEM and UV-visible characterization showed that the ZnO NRs structures and the optical absorption were almost the same as the unused ZnO NRs. A single channel photocatalytic reactor was developed and utilized to degrade natural textile wastewater (TWW). The removal efficiency of color in the sample was measured using UV-visible spectroscopy. Discoloration (color degradation) reached 96 % after 240 minutes of the photocatalytic process. The total organic carbon (TOC) was used to investigate the mineralization of TWW. It was found that the total organic content in TWW decreased to 49 % after 7 hours of sunlight irradiation using ZnO NRs