Photocatalysis is a highly promising technology which utilized photon energy for the mineralization of organic pollutants through chemical oxidation reaction processes. Post-treatment is needed to recover the photocatalyst from the solution after the reaction. Membrane filtration is integrated to the photocatalysis process due to their ability to reject the suspended photocatalyst and further improving the permeate quality by rejecting un-treated or remained organic matter in the feed. However, the major drawback of the integration is membrane fouling. Severe membrane fouling occurred due to the filtration of feed containing mixture of organic matter and photocatalyst. Continuous decline of photocatalyst in the bulk feed solution could happen due to the filtration process / precipitation on the membrane and thus decrease the degradation efficiency. The main purpose of this work was to develop an integrated photocatalytic reactor / membrane system in water treatment using solar and ultraviolet irradiation. Zinc oxide (ZnO) was selected as photocatalyst due to its excellent electrical, mechanical, and optical properties which are quite similar but cheaper compared to TiO₂ . A simple sol-gel method at low temperature was used to prepare ZnO nanoparticles. Performance of ZnO was improved by using different solvents, doped with Fe ³⁺ and coupled with graphene oxide (GO). ZnO has the particle size range from 10-50 nm. Photocatalytic activities of ZnO and Fe-doped ZnO samples were evaluated based on the removal of Congo red (CR) using solar irradiation. 1.5 wt.% Of Fe ³⁺ doped ZnO (FZ-3) was able to attain ~ 70% CR degradation. It was the highest among different Fe ³⁺wt.%. The best FZ-3 was then used to fabricate nanoparticles with graphene oxide (FZG-3) for performance enhancement. 24% of degradation improvement was achieved by layering FZ-3 onto graphene oxide. In the recovery step of the photocatalyst, serious membrane flux decline and fouling layer on membrane was found. To study the most suitable options to reduce membrane fouling, mitigation of organic fouling of ceramic membranes in submerged photocatalytic membrane reactor (SPMR) was also investigated in this work using custom-made membrane reactor, where UV irradiation source and the membrane modules are integrated in the same reactor. In parallel, the performance of the combined photocatalytic process and membrane filtration with respect to the removal of natural organic matter (NOM) was also studied in terms of time-dependent and overall removals. ZnO was employed as a photocatalyst and potting soil extract (B2000) as NOM surrogate. Experiments were conducted in batch and continuous modes. Photocatalysis process was able to reduce the membrane fouling by ~ 80% and ~ 47% in batch and continuous mode, respectively, compared to without photocatalysis. SPMR was able to retain up to ~ 90% of ZnO in the system. These findings indicate that properties of photocatalyst is vital in determining efficiency of photocatalysis. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. Experiments were conducted in batch and continuous modes. Photocatalysis process was able to reduce the membrane fouling by ~ 80% and ~ 47% in batch and continuous mode, respectively, compared to without photocatalysis. SPMR was able to retain up to ~ 90% of ZnO in the system. These findings indicate that properties of photocatalyst is vital in determining efficiency of photocatalysis. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. Experiments were conducted in batch and continuous modes. Photocatalysis process was able to reduce the membrane fouling by ~ 80% and ~ 47% in batch and continuous mode, respectively, compared to without photocatalysis. SPMR was able to retain up to ~ 90% of ZnO in the system. These findings indicate that properties of photocatalyst is vital in determining efficiency of photocatalysis. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. respectively, compared to without photocatalysis. SPMR was able to retain up to ~ 90% of ZnO in the system. These findings indicate that properties of photocatalyst is vital in determining efficiency of photocatalysis. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. respectively, compared to without photocatalysis. SPMR was able to retain up to ~ 90% of ZnO in the system. These findings indicate that properties of photocatalyst is vital in determining efficiency of photocatalysis. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future. The findings also highlight that it is possible to mitigate and control the membrane fouling in the PMR using photocatalysis process by manipulating the operating conditions. All these findings and challenges are important for the implementation of the photocatalysis process in water treatment in future.