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Effects of pH and Iron Concentrations on Sulfide Precipitation in Wastewater Collection Systems
Author(s) -
Nielsen Asbjørn Haaning,
HvitvedJacobsen Thorkild,
Vollertsen Jes
Publication year - 2008
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143007x221328
Subject(s) - ferrous , sulfide , chemistry , precipitation , wastewater , sulfate , ferric , inorganic chemistry , iron sulfide , chloride , hydrogen sulfide , environmental chemistry , environmental engineering , sulfur , environmental science , organic chemistry , physics , meteorology
Sulfide precipitation by addition of iron salts is a widely used strategy for sulfide control in wastewater collection systems. Several parameters, such as pH, oxidation–reduction conditions, and reactant concentrations, are known to affect the feasibility of the method. However, their combined effects are difficult to predict for complex media, such as wastewater. This study investigates the effect of pH and reactant concentrations on the efficiency of iron sulfide precipitation in anaerobic municipal wastewater. Laboratory experiments showed that, when the pH was below 7, typically less than 40% of the added ferrous iron reacted by sulfide precipitation, although sulfide was in excess. However, when the pH was above 8, almost complete precipitation of all the added ferrous iron was observed. Varying the ferric‐iron‐to‐ferrous‐iron ratio demonstrated that improved efficiency could be achieved when using a 1:1 mixture of ferric chloride and ferrous sulfate.