Summary: The photocatalysis technology suffers a yawning gap between the extravagant academic studies and substantive implementation. The viability of photocatalysis may thrive by steering the research towards the reactor design, fixed photocatalysts, real wastes, and cost estimation. Herein, we prepared novel nanocomposites of metal-organic framework-808 (MOF-808) and carbon nanotubes (CNTs) with different ratios to employ them in the photocatalytic degradation of carbamazepine (CBZ) and diazinon. A photocatalytic reactor with CNTs/MOF-808 painted plates was employed to use the catalyst in a reusable form. Various analyses were conducted to study the morphology and composition of CNTs/MOF-808 composites. The response surface methodology (RSM) was used for the optimizing the operational parameters. The reuse of the coated plates in continuous cycles indicated the proper stability of CNTs/MOF-808. For instance, the degradation of diazinon was 99.7%, 96.3%, 94.8%, 93.5% and 92.1% for five cycles. The degradation mechanism and the oxidation pathways have been intensively investigated. Furthermore, the reactor was employed for the treatment of real agrochemical and pharmaceutical liquid wastes showing a reduction in the total organic carbon (TOC) by 93% and 76%, respectively. A cost-estimation study implies that a large-scale photocatalytic system costs 2.523 $/m, including the amortization and operating costs.