Inorganic nitrogen removal by a marine purple sulfur bacterium capable of growth on nitrite as sole nitrogen source

Abstract:

[Objective] To clarify the removal of ammonium, nitrate and nitrite by a marine purple sulfur bacterium capable of growing on nitrite as sole nitrogen source. [Methods] Ammonium, nitrate and nitrite concentration in simulated wastewater were determined using the Nessler’s reagent spectrophotometry, N-(1-naphthyl)-1,2-diaminoethane dihydrochloride spectrophotometry, UV spectrophotometry, respectively. [Results] The removal of ammonium, nitrate and nitrite as well as bacterial biomass and pH increased with time, and then tended to equilibrium. Strain YL28 exhibited effective ammonium removal ability, with a maximal removal and tolerance of 9.64 mmol/L and 36.64 mmol/L, respectively. The removal rate exceeded 97.61% when the concentration of ammonium was less than 3.21 mmol/L. Compared to ammonium, the cell growth rate, biomass and pH of wastewater enhanced slowly while using nitrate and nitrite as sole nitrogen source. However, the removal of nitrate and nitrite were higher than that of ammonium. Nitrate and nitrite in wastewater could be completely removed when their concentrations were up to 13.50 mmol/L and 22.90 mmol/L, respectively. When the three inorganic nitrogen existed simultaneously in wastewater, ammonium, nitrate and nitrate could be removed by strain YL28, the removal of nitrate and nitrite was higher than that of ammonium. [Conclusion] Strain YL28 would be a promising candidate for bioremediation of polluted aquaculture wastewater, especially for nitrite-polluted marine culture wastewater.