The Effect of Sodium Chloride on the Denitrification of Saline Fishery Wastewaters

摘要

The effect of sodium chloride concentration (0.47-100 g l~(-1)) on the rates of nitrate and nitrite reduction was studied at 37℃ and pH 7.5 in a batch reactor fed with a mixture (v/v) of salmon bloodwater and synthetic substrate and inoculated with biomass adapted to saline conditions (24 g NaCl per litre). NaCl inhibited the nitrate and nitrite reduction rates; the rates were increasingly inhibited at increasing NaCl concentrations in the studied concentration range. An empiric non-competitive model adequately quantified the effect of NaCl on the rates of nitrate and nitrite reduction. The maximum reduction rate (R_(D,max)) in a low salt medium and the inhibition constant (K_1) were determined for each reductive step. The calculated kinetic parameters were R_(D,max) = 25.5 ± 0.74 mg N (g VSS h)~(-1) and K_1 = 34.9 ± 2.34 × 10~(-3) g l~(-1) for nitrate reduction and R(D,max) = 18.7 ± 1.05 mg N (g VSS h)~(-1) and K_1 = 62.5 ± 3.32 × 10~(-3) g l~(-1) for nitrite reduction. NaCl has a greater effect on nitrite reduction rate than on the nitrate reduction rate.