# NO minus ndash N removal efficiency of ndash was

Dissolved oxygen (DO) concentrations ranged between 5 and 9 mg L−1 indicating mostly oxidising environments in the study areas and electron activity redox values were between 12 and 14.

2.4. Statistical analysis

Correlation and statistical evaluation was done with one-way Analysis of Variance (ANOVA), using Analysis ToolPak in Excell Add-in Software. Statistical differences were analysed by computing the Pearson correlation with p-values lower than p = 0.05 considered to be significant.