Decrease of dissolved sulfide in sewage by powdered natural magnetite and hematite

Promotion of Para-Chlorophenol Reduction and Extracellular Electron Transfer in an Anaerobic System at the Presence of Iron-Oxides

“…Various iron-oxides, such as hematite, magnetite, and ferrihydrite, have been widely applied in wastewater remediation for the removal of heavy metal (Lin et al, 2017), dissolved sulfide (Zhang et al, 2016), and radionuclides (El Afifi et al, 2016). Recently, attention has been increasingly paid to the combined utilization of various iron-oxides into the anaerobic wastewater treatment system.…”

Electrochemical Production of Magnetite Nanoparticles for Sulfide Control in Sewers

“…Magnetite, Fe 2+ (Fe 3+ ) 2 O 4 or in short Fe 3 O 4 , is a mixed-valence ferrimagnetic iron oxide which has been widely applied in several industrial processes, environmental and biomedical applications. − In a recent study, purchased magnetite powder (a particle size range of 45–60 μm) reduced the sulfide level in synthetic sewage, thereby showing the feasibility of using magnetite for sulfide control in sewers . However, the study suggested that the metal impurities in raw magnetite should be limited to acceptable content in order to minimize the impact on sewage quality . Indeed, heavy metal contents (e.g., Cr, Zn, Ni, Sn, etc.)…”

“…Zhang et al showed that with the reported optimal magnetite dosage of 40 mg/L, sulfide concentration was reduced from 6.5 mg/L to 1.3 mg/L (i.e., a 79% sulfide reduction; equivalent to a sulfide removal capacity of 197.3 mg S/g Fe 3 O 4 –Fe) over a period of 96 h. Better sulfide control performance of magnetite is necessary as minor concrete corrosion may already occur at sulfide concentration of 0.1 to 0.5 mg S/L, which indicates more input of magnetite is needed in order to further lower the sulfide concentration to less than 0.5 mg S/L. However, the study showed that the lowest attainable sulfide concentration using powdered magnetite was around 1.1 mg S/L at magnetite dosage of 60 mg/L, increasing magnetite dosage from 60 to 100 mg/L did not further reduce the sulfide concentration .…”

“…Zhang et al showed that with the reported optimal magnetite dosage of 40 mg/L, sulfide concentration was reduced from 6.5 mg/L to 1.3 mg/L (i.e., a 79% sulfide reduction; equivalent to a sulfide removal capacity of 197.3 mg S/g Fe 3 O 4 –Fe) over a period of 96 h. Better sulfide control performance of magnetite is necessary as minor concrete corrosion may already occur at sulfide concentration of 0.1 to 0.5 mg S/L, which indicates more input of magnetite is needed in order to further lower the sulfide concentration to less than 0.5 mg S/L. However, the study showed that the lowest attainable sulfide concentration using powdered magnetite was around 1.1 mg S/L at magnetite dosage of 60 mg/L, increasing magnetite dosage from 60 to 100 mg/L did not further reduce the sulfide concentration . In addition, many studies have indicated that nanoscale magnetite exhibits adsorbent properties and suggested that the smaller the particle size, the higher capacity of magnetite to reduce contaminants (e.g., arsenite, arsenate, and phosphate). − Hence, reducing the magnetite particle size from microscale (i.e., purchased magnetite powder; with a particle size range of 45–60 μm) to nanoscale is likely to improve its capability of sulfide control, resulting in lower sulfide concentration in sewage.…”

“…7−11 In a recent study, purchased magnetite powder (a particle size range of 45−60 μm) reduced the sulfide level in synthetic sewage, thereby showing the feasibility of using magnetite for sulfide control in sewers. 12 However, the study suggested that the metal impurities in raw magnetite should be limited to acceptable content in order to minimize the impact on sewage quality. 12 Indeed, heavy metal contents (e.g., Cr, Zn, Ni, Sn, etc.)…”