کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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4453666 | 1620810 | 2016 | 6 صفحه PDF | دانلود رایگان |
Nitrate-nitrogen (NO3−-N) always accumulates in commercial recirculating aquaculture systems (RASs) with aerobic nitrification units. The ability to reduce NO3−-N consistently and confidently could help RASs to become more sustainable. The rich dissolved oxygen (DO) content and sensitive organisms stocked in RASs increase the difficulty of denitrifying technology. A denitrifying process using biologically degradable polymers as an organic carbon source and biofilm carrier was proposed because of its space-efficient nature and strong ability to remove NO3−-N from RASs. The effect of dissolved oxygen (DO) levels on heterotrophic denitrification in fixed-film reactors filled with polycaprolactone (PCL) was explored in the current experiment. DO conditions in the influent of the denitrifying reactors were set up as follows: the anoxic treatment group (Group A, average DO concentration of 0.28 ± 0.05 mg/L), the low-oxygen treatment DO group (Group B, average DO concentration of 2.50 ± 0.24 mg/L) and the aerated treatment group (Group C, average DO concentration of 5.63 ± 0.57 mg/L). Feeding with 200 mg/L of NO3−-N, the NO3−-N removal rates were 1.53, 1.60 and 1.42 kg/m3 PCL/day in Groups A, B and C, respectively. No significant difference in NO3−-N removal rates was observed among the three treatments. It was concluded that the inhibitory effects of DO concentrations lower than 6 mg/L on heterotrophic denitrification in the fixed-film reactors filled with PCL can be mitigated.
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Journal: Journal of Environmental Sciences - Volume 43, May 2016, Pages 147–152