Pre-treatment of chemical synthetic pharmaceutical wastewater using a combined internal electrolysis-fenton process

A combined internal electrolysis-Fenton technology was used to treat chemical synthetic pharmaceutical wastewater. The combined technology presented a higher COD removal than those by the only internal electrolysis technology. The experimental results indicated the COD removal efficiency by the combined technology could achieve as high as 60% under the conditions that H₂O₂ concentration was 50mg/L, the Fenton oxidation pH was 3 and the reaction time for Fenton oxidation was 45 min. Further, the combined technology remarkably improved the biodegradability of wastewater by increasing the B/C values from 0.21 to 0.32. An acute biotoxicity assay measuring the inhibition of bioluminescence showed that the acute toxicity of pharmaceutical wastewater was reduced from 4.5 mgZn²⁺/L to 0.9mgZn²⁺/L, suggesting a detoxifying effect by the combined technology.