Simultaneous biological removal of nitrogen, carbon and sulfur by denitrification

• Published in: Water research (Oxford) 2004-08, Vol.38 (14), p.3313-3321
• Main Authors: Reyes-Avila, Jesús, Razo-Flores, Elı́as, Gomez, Jorge
• Format: Article
• Language: English
• Subjects: Acetates - chemistry; Anoxic sulfide oxidation; Applied sciences; Bacteria, Anaerobic - metabolism; Biological and medical sciences; Biological treatment of waters; Biomass; Bioreactors; Biotechnology; Carbon - isolation & purification; Carbon - metabolism; Denitrification; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrocarbons, Aromatic - chemistry; Industrial applications and implications. Economical aspects; Industrial wastewaters; Nitrate reduction; Nitrates - chemistry; Nitrates - metabolism; Nitrites - chemistry; Nitrites - metabolism; Nitrogen - isolation & purification; Nitrogen - metabolism; Oxidation-Reduction; Petroleum; Pollution; Quaternary Ammonium Compounds - chemistry; Sulfides - chemistry; Sulfur - isolation & purification; Sulfur - metabolism; Sulfur production; Waste Disposal, Fluid - methods; Wastewaters; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2004.04.035

Refinery wastewaters may contain aromatic compounds and high concentrations of sulfide and ammonium which must be removed before discharging into water bodies. In this work, biological denitrification was used to eliminate carbon, nitrogen and sulfur in an anaerobic continuous stirred tank reactor of 1.3 L and a hydraulic retention time of 2 d. Acetate and nitrate at a C/N ratio of 1.45 were fed at loading rates of 0.29 kg C/m 3 d and 0.2 kg N/m 3 d, respectively. Under steady-state denitrifying conditions, the carbon and nitrogen removal efficiencies were higher than 90%. Also, under these conditions, sulfide (S 2−) was fed to the reactor at several sulfide loading rates (0.042–0.294 kg S 2−/m 3 d). The high nitrate removal efficiency of the denitrification process was maintained along the whole process, whereas the carbon removal was 65% even at sulfide loading rates of 0.294 kg S 2−/m 3 d. The sulfide removal increased up to ∼99% via partial oxidation to insoluble elemental sulfur (S 0) that accumulated inside the reactor. These results indicated that denitrification is a feasible process for the simultaneous removal of nitrogen, carbon and sulfur from effluents of the petroleum industry.