Continuous photocatalytic set-up assisted with nano TiO₂ plate for tannery wastewater treatment

A novel photocatalytic continuous system has been proposed for the treatment of tannery waste water, which has high levels of environmental pollutants. The purification process was performed by passing wastewater on a titanium dioxide (TiO₂)-coated surface, which is continuously activated by irradiation of ultraviolet light. To improve the yield of the process, ferric chloride (FeCl₃) was used as a coagulation agent. The organic and inorganic compounds, as well as the microorganisms in the tannery wastewater media, were degraded through a photocatalytic process. The results revealed that total dissolved solids and total suspended solids contents were significantly decreased from 8,450 and 8,990 mg·L^-1 to 4,032 and 4,127 mg·L^-1, respectively. Furthermore, the chemical oxygen demand content of the sample was reduced from 370 to 50 mg·L^-1 after the addition of 100 mL of FeCl₃ and 4 h of treatment. The same results were observed for the elimination of sulfate and chromium ions, which led to a decline in electrical conductivity. This suggests that introducing 100 mL of FeCl₃ as the coagulation agent and continuous treatment with photocatalityc set-up could be considered as an effective method for the purification of tannery wastewaters.