Ferrate as a coagulant prior to sand filters treating secondary wastewater effluent for reuse

Abstract

Wastewater reuse is one of the crucial water resources in Egypt due to the ongoing need to increase water resources and close the supply-demand gap. In this study, a new coagulant has been investigated before sand filters as an advanced wastewater treatment method. The sand filter pilot was run at a hydraulic loading rate of 0.75 m/h and two different dosages of three coagulants (Alum, FeCl3, and Ferrate VI) were selected using the jar tests. The sand filter without coagulant removed 12% of BOD5 and 70% of turbidity. Applying in-line coagulation before the sand filter provided effluents with better quality, especially for turbidity, organics, and microorganisms. Ferrate provided the highest removal of turbidity (90%) and BOD5 (93%) at very low dosages and lower costs compared with other coagulants, however, it adversely impacted both conductivity and dissolved solids. A significant effect on reducing bacteria was obtained with 40.0 mg/L of alum. According to the study's findings, the ferrate coagulant enhanced the sand filter's performance producing effluents with high quality, enabling it to meet strict water reuse regulations as well as aquatic environmental and health preservations. HIGHLIGHTS Conventional sand filters as advanced wastewater treatment assist in solving water scarcity.; A novel coagulant was investigated before sand filter.; Water quality was improved to be reused in agriculture.; Using this new coagulant reduces both the use of chemicals and the costs.; The coagulant type and dosage impact the filter performance.;

Keywords

• advanced wastewater treatment
• ferrate vi
• in-line coagulation
• sand filter
• secondary effluent