title: Nitrate promotes biological oxidation of sulfide in wastewaters: experiment at plant-scale.
abstract: Biogenic production of sulfide in wastewater treatment plants involves odors, toxicity and corrosion problems. The production of sulfide is a consequence of bacterial activity, mainly sulfate-reducing bacteria (SRB). To prevent this production, the efficiency of nitrate addition to wastewater was tested at plant-scale by dosing concentrated calcium nitrate (Nutriox) in the works inlet. Nutriox dosing resulted in a sharp decrease of sulfide, both in the air and in the bulk water, reaching maximum decreases of 98.7% and 94.7%, respectively. Quantitative molecular microbiology techniques indicated that the involved mechanism is the development of the nitrate-reducing, sulfide-oxidizing bacterium Thiomicrospira denitrificans instead of the direct inhibition of the SRB community. Denitrification rate in primary sedimentation tanks was enhanced by nitrate, being this almost completely consumed. No significant increase of inorganic nitrogen was found in the discharged effluent, thus reducing potential environmental hazards to receiving waters. This study demonstrates the effectiveness of nitrate addition in controlling sulfide generation at plant-scale, provides the mechanism and supports the environmental adequacy of this strategy.
authors.affiliation: Dpto. Biología, Facultad de Ciencias del Mary Ambientales, Pol. Río San Pedro s/n, 11510-Pto. Real, Cádiz, Spain. juan.garciadelomas@uca.es
authors.forename: Juan
authors.initials: J
authors.lastname: García de Lomas
authors.forename: Alfonso
authors.initials: A
authors.lastname: Corzo
authors.forename: Juan M
authors.initials: JM
authors.lastname: Gonzalez
authors.forename: Jose A
authors.initials: JA
authors.lastname: Andrades
authors.forename: Emilio
authors.initials: E
authors.lastname: Iglesias
authors.forename: María José
authors.initials: MJ
authors.lastname: Montero
mesh_terms: D017610:Calcium Compounds / Q000494:pharmacology*; D006862:Hydrogen Sulfide / Q000378:metabolism*; D009566:Nitrates / Q000494:pharmacology*; D009584:Nitrogen / Q000378:metabolism; D010084:Oxidation-Reduction; D044147:Piscirickettsiaceae / Q000187:drug effects* / Q000378:metabolism; D012329:RNA, Bacterial / Q000032:analysis / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D013855:Thiobacillus / Q000187:drug effects / Q000378:metabolism; D014865:Waste Disposal, Fluid
chemical_list: D017610:Calcium Compounds; D009566:Nitrates; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D009584:Nitrogen; C059948:calcium nitrate; D006862:Hydrogen Sulfide