Study on removal of phosphorus and COD in wastewater by sinusoidal AC Fenton oxidation-coagulation

In order to treat domestic wastewater containing phosphorus and chemical oxygen demand (COD), the new technology of Sinusoidal Alternating Current (AC) Fenton Oxidation-Coagulation (SACFOC) was used to improve the removal efficiency (R-e) and reduce energy consumption (EEC). The morphology, elemental composition, crystal structure and functional groups of the sludge were characterised by Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDS), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The results show that total phosphorus removal efficiency {R-e(TP)} and removal efficiency of organic matter {R-e(COD)} can reach 97.56% and 87.77%, respectively, but EEC is only 0.09 kWh center dot m(-3) under the optimum conditions of pH(0) = 3, current density (j) = 0.5 A center dot m(-2), c(0)(TP) = 18 mg center dot dm(-3), c(0)(COD) = 300 mg center dot dm(-3), c(0)(H2O2) = 0.06 mol center dot dm(-3), t = 45 min. As compared with direct current (DC) Fenton Oxidation-Coagulation (DCFOC), the COD removal efficiency of SACFOC treatment was improved by 37%, but the energy consumption was reduced by 45%. The degradation process of total phosphorus and COD by SACFOC abides by the quasi-first-order kinetic model. The process of SACFOC includes double effects of electrocoagulation of iron sol by electrolysis and degrade COD by oxidation of formed hydroxyl radicals (center dot OH) in wastewater, which improves removal efficiency of total phosphorus and COD in wastewater. Our research findings will provide technical guidance and a theoretical basis for the simultaneous treatment of wastewater containing phosphorus and COD applying SACFOC process.

Automated summary

In this study, the new technology of SACFOC was used to treat domestic wastewater containing phosphorus and COD. The results showed that under the optimum conditions, high removal efficiency could be achieved with low energy consumption. SACFOC effectively removed both total phosphorus and COD through electrocoagulation and oxidation. The findings of this research will provide technical guidance and a theoretical basis for wastewater treatment.