Iranian Journal of

Background and Objectives:Antibiotics and hormones are excreted with other wastes following their influences on bodies.These substances can disturbed treatment process by their entery to the wastewater. In this study the inhibitory behavior of antibiotics Ofloxacin and Ciprofloxacin and hormone stradiol 17- valerat have been investigated on Specific Methanogenic Activity (SMA) of anaerobic biomass.
Materials and Methods: Twenty one SMA tests were done using 120-mLvials in batch mode. In each vial, substrate, biomass and biogas were occupied 66, 17, and 17 % (v/v), respectively. Each test longed in range of 15-30 days. Produced methane was measured by gas replacement with 2N KOH solution as CO2 absorbent.
Results: In this study, at the concentrations of 200, 500 and 1000 mg/L of antibiotic Ofloxacin, the methane production reduced to 45, 76 and 88 percent, respectively. Reduced methane production of 68, 81 and 88 percent was observed in Ciprofloxacin concentrations of 100, 200, and 500 mg/L, respectively. Cumulative methane at the concentrations of 0.1, 1, and 5 mg E2 /L was 66, 90, and 121 mL, respectively
Conclusion: Antibiotic Ciprofloxacin at concentrations similar to the antibiotic Ofloxacin have a greater inhibitory effect on specific methanogenic activity of anaerobic biomass. Also, the hormone E2 at lower concentrations showed more inhibitory effect than other two antibiotics Ciprofloxacin and Ofloxacin.