Sulfide oxidation in fluidized bed bioreactor using nylon support material

Effect of Dissolved Oxygen Concentrations on Specific Microbial Activities and Their Metabolic Products in Simultaneous Sulfur and Nitrogen Removal

“…Production of S 0 was reduced when DO concentration increased. With inoculation under DO concentration of 0.05-0.15 mg/L, S 0 production was higher than remaining SO 4 2--S. However, when DO concentration was up to 0.15-0.30 mg/L, the main sulfur compound in batch experiment was SO 4 2--S. Reference [8] reported that at DO less than 0.1 mg/L, S 0 was the main product of the sulfide oxidation process. They also explained that production of S 0 by SOB decreased at high DO concentration [8].…”

“…Synthetic wastewater was prepared to simulate concentrated latex wastewater by using lactic acid, anhydrous sodium sulfate (Na 2 SO 4 ) and ammonium chloride (NH 4 Cl) as sources of carbon, sulfate and ammonium nitrogen, respectively [6], [9]. In the reactor, SO 4 2-, NH 4 + -N and COD was added to an initial concentration of 1,000, 222.2 and 4,000 mg/L respectively as shown in Table I. The influent pH value was maintained at 7.0 by dosing NaOH [9].…”

“…Vials were flushed with helium gas for 5 minutes to expel oxygen gas and subsequently sealed with butyl rubber stoppers and aluminum seals [3], [12]. Lactic acid and Na 2 SO 4 were added to the medium to give final concentrations of 6.0 g-COD/L and 2.0 g-SO 4 2-/L, respectively. 10 mL samples were taken and centrifuged, 5 mL of supernatant was then analyzed for sulfate reduction.…”

“…At the end of the experiment, concentrations of SO 4 2-, S 2-, S 2 O 3 2-, NH 4 + , NO 3 -and NO 2 -in liquor samples were measured after centrifugation at 4500 rpm for 10 minutes. Sulfate was analyzed according to Turbidimetric method [11].…”

“…In addition, nitrogen compounds afford risks associated with toxicity and bad odor in water, leading to eutrophication and serious ecological damage to the receiving water bodies [1], [3]. In order to remove sulfate and nitrogen contaminants, biological treatments are preferred technologies rather than physical-chemical methods, which are expensive and may generate toxic residuals [4]. The conventional biological process to treat sulfate rich wastewater consists of two processes, sulfate reducing to sulfide by sulfate reducing bacteria (SRB) under anaerobic condition, and sulfide oxidizing to elemental sulfur (S 0 ) by sulfide oxidation bacteria (SOB) under micro-aeration conditions or by autotrophic denitrifier under anaerobic conditions in presence of nitrate.…”