Figure 5

Variation of nitrogen species and microorganism in the presence of humic acid as an electron donor (Run8-11). Initial humic acid concentrations are 0 (small black circles and dotted line), 10 (black marks), 100 (gray marks) and 1000 (white marks) mg/dm³. Other initial conditions are the same: initial concentrations of NO₃ ^– and microorganism (Azoarcus tolulyticus) were 50 mmol/dm³and 1000 mg/dm³, respectively. Lines are shown to help identify the general trends shown by the data.