Stability and efficiency of Fe3+ EDDS complex for the treatment of secondary effluent in the photo-Fenton process

This study focuses on the use of Fe3+ EDDS for degradation of methylene blue and wastewater disinfection using the photo-Fenton process. The stability of Fe3+ EDDS was tested at different pH values ranging from 4 to 11. The study finds that an increase in the iron precipitate and a decrease in degradation efficiency comes about as pH increases. An investigation into the Fe:L ratio shows that when a high amount of ligand is used, the amount of iron released from the complex is reduced; with an iron-ligand ratio of 1:1.5 being the most suitable one for the Fe3+ EDDS system. Furthermore, the result of careful examination of temperature changes shows that at the increase in temperature of the reaction system, there was a decrease in the efficiency of degradation of reaction. The process was more effective at a temperature of 25 degrees C than at higher temperatures, occasioned by higher iron precipitate. The results of the disinfection and regrowth of microorganisms also show that the efficiency of the process is pH-dependent with pH 7 having the best disinfection and less regrowth rate as compared to a pH value of 9, for instance.