title: Nitrite and nitrate as electron acceptors for biological sulphide oxidation.
abstract: Autotrophic denitrification with sulphide using nitrate (R1) and nitrite (R2) as electron acceptor was investigated at bench scale. Different solids retention times (SRT) (5 and 20 d) have been tested in R1 while R2 was operated at SRT=13 d. The results indicated that the process allows complete sulphide removal to be achieved in all tested conditions. Tested sulphide loads were estimated from the H2S produced in a pilot-scale anaerobic digester treating vegetable tannery primary sludge; nitrogen loads originated from the nitrification of the supernatant. Average nitrogen removal efficiencies higher than 80% were observed in all the tested conditions once steady state was reached. A maximum specific nitrate removal rate equal to 0.35 g N-NO3- g VSS(-1) d(-1) was reached in R1. Due to sulphide limitation, incomplete denitrification was observed and nitrite and thiosulphate tend to accumulate especially in the presence of variable environmental conditions in both R1 and R2. Lower SRT caused higher NO2accumulated/NO3reduced ratios (0.22 and 0.24, with SRT of 5 d and 20 d, respectively) using nitrate as electron acceptor in steady-state condition. Temperature decrease caused sudden NO2accumulated/NO3reduced ratio increase in R1 and NO2- removal decrease in R2.
authors.affiliation: Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy E-mail: alberto.mannucci@dicea.unifi.it.
authors.forename: G
authors.initials: G
authors.lastname: Munz
authors.affiliation: Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy E-mail: alberto.mannucci@dicea.unifi.it.
authors.forename: A
authors.initials: A
authors.lastname: Mannucci
authors.affiliation: Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico.
authors.forename: J
authors.initials: J
authors.lastname: Arreola-Vargas
authors.affiliation: Instituto Potosino de Investigacion Cientifica y Tecnologica, Camino a la Presa San José 2055, 78216 San Luis Potosí, Mexico.
authors.forename: F
authors.initials: F
authors.lastname: Alatriste-Mondragon
authors.affiliation: Department of Civil and Environmental Engineering, University of Florence, Via S. Marta 3, 50139 Florence, Italy E-mail: alberto.mannucci@dicea.unifi.it.
authors.forename: F
authors.initials: F
authors.lastname: Giaccherini
authors.affiliation: Cer2co (Centro Ricerca Reflui Conciari), Consorzio Cuoiodepur, Via Arginale Ovest 56020 San Romano - San Miniato (PISA), Italy.
authors.forename: G
authors.initials: G
authors.lastname: Mori
mesh_terms: D019149:Bioreactors; D058440:Denitrification; D007220:Industrial Waste / Q000032:analysis*; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D012722:Sewage / Q000032:analysis; D013440:Sulfides / Q000378:metabolism*; D013633:Tanning; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000032:analysis*
chemical_list: D007220:Industrial Waste; D009566:Nitrates; D009573:Nitrites; D009584:Nitrogen; D012722:Sewage; D013440:Sulfides; D062065:Wastewater