In this research, several visible-light driven photocatalysts were developed and their photocatalytic activities were evaluated in the removal of organic pollutants. Wastewater containing pathogen carriers such as total coliforms, and E. coli was tested for disinfection using the synthesized visible-light photocatalysts. Graphitic carbon nitride (GCN or g-C3N4), a visible-light driven photocatalyst, was synthesized from different precursors. Also, different composites of GCN such GCN/Ag2CrO4, and GCN/ZnO-Cu were synthesized. The purpose of these GCN composites is to enhance the photocatalytic activity of the GCN. Several characterization techniques were used to understand the physicochemical properties of the photocatalysts. The initial photocatalytic experiments, detailed in Chapter 3, were on degrading 4-CP under a royal blue LED (450 nm) using precursor-derived GCNs and GCN composites. The results show that the GCN/0.3Ag2CrO4 performed well with over 95% degradation of 4-CP. The second set of photocatalytic experiments, detailed in Chapter 4, were on investigating the degradation of 2,4-D and MCPP, BSA protein, SARS-CoV-2 (Covid-19) spike protein, cATP, and total coliforms/E. coli using the best performing GCN/0.3Ag2CrO4 in the first photocatalytic experiments and royal blue LED. Over 85% of 2,4-D and MCPP were simultaneously degraded, 77.5% of Covid-19 spike protein was achieved, and over one log reduction of cATP, total coliforms/E. coli was achieved in wastewater treatment. In Chapter 5 (third set of experiments), new sets of photocatalysts were synthesized. GCN/0.1ZnO-Cu3% performed best with over 65% of 4-CP degradation under royal blue LED. A complete 5.5 log reduction of coliforms-containing wastewater primary influent was achieved with the same photocatalyst. In Chapter 6, the best-performing GCN/ZnO-Cu nanocomposite in observed in chapter 5 was coated on a polyvinyl chloride (PVC) substrate and the performance was evaluated under a 5000K LED (400 – 700 nm). The result shows a 2-log reduction of the coliform-containing wastewater treatment on the self-disinfecting coated surface. To the best of our knowledge, this is the first research to investigate the comprehensive use and practical application of self-disinfecting coated surfaces under commercial and industrial light (5000K LED) irradiation. All our results demonstrate that compositing GCN with metals can degrade pollutants and disinfect wastewater under visible light irradiation.