title: Oxygen Demand of Fresh and Stored Sulfide Solutions and Sulfide-Rich Constructed Wetland Effluent.
abstract: This study investigated the contribution of hydrogen sulfide to biological oxygen demand (BOD5) and chemical oxygen demand (COD) in wastewater effluents, and documented the effect of storage times and conditions on the BOD5 and COD of pH-adjusted sodium sulfide solutions as well as graywater wetland effluent. Initial COD measurements of sulfide solutions were 84-89% of the theoretical oxygen demand (ThOD), 1.996 mg O2/mg S, whereas unseeded BOD5 measurements were 55-77%. For sulfide solutions, all storage conditions led to declines of >15% (COD, BOD5), and >31% (sulfide). For wetland effluent, storage without headspace was effective in reducing COD losses (3.7%), compared to storage with headspace (17%), and affected changes in turbidity, UVA-254 and pH. The results suggest that storage times and conditions should be controlled and reported when reporting BOD5 and COD of sulfide-rich samples. Wetland models representing sulfate reduction as a method of COD removal may need to be reconsidered.
authors.affiliation: School of Engineering, University of Guelph, 50 Stone Road East, Guelph, Ontario, N1G 2W1, Canada.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Chan
authors.forename: Khosrow
authors.initials: K
authors.lastname: Farahbakhsh
mesh_terms: D057919:Biological Oxygen Demand Analysis; D006862:Hydrogen Sulfide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012996:Solutions; D013997:Time Factors; D014466:Ultraviolet Rays; D062065:Wastewater / Q000737:chemistry; D018508:Water Purification; D053833:Wetlands
chemical_list: D006862:Hydrogen Sulfide; D012996:Solutions; D062065:Wastewater