3. Results and discussions
3.1. Characterization of influent wastewater
Analysis of 25 samples of influent wastewater to VFCW indicated that the organic loading rate varied during the period
of this study. The COD ranged between 185 mg/l and 335 mg/l,
while BOD values varied between 59 mg/l and 175 mg/l. The
average suspended solids concentration was 94 mg/l, while the
average concentration of ammonia, TKN and total phosphorus
were 16.7 mg/l, 30.7 mg/l and 3.15 mg/l, respectively. The average bacterial indicators counts were 2.8 × 10
7
MPN/100 ml for
total coliform and 2.3 ×10
6
MPN/100 ml for fecal coliforms and
2.4 × 10
6
MPN/100 ml for E. coli. Analysis of heavy metals such as
mercury, lead, cupper, cadmium, and chromium indicated that the
concentration each metal did not exceed 0.001 mg/l