Treatment of E. coli HB101 and the tetM gene by Fenton's reagent and ozone in cow manure.

The destruction of antibiotic-resistant microorganisms at the source of contamination is necessary due to their adverse effects and to their increasingly widespread occurrence in the environment. To address this problem, Fenton and ozone oxidation processes were applied to synthetically contaminated cow manure to remove the tetM gene and its host, Escherichia coli HB101. The efficiency of the processes was evaluated by enumeration of E. coli HB101 and by PCR amplification of the tetM gene. The results of this study show that 56.60% bacterial inactivation (corresponding to a 0.36 log reduction) was achieved by a Fenton reagent dose of 50 mM H(2)O(2) and 5 mM Fe(2+) without acidifying the manure. Despite the high organic content of cow manure, 98.50% bacterial inactivation (corresponding to a 1.83 log reduction) was obtained by the ozonation process with an applied dose of 3.125 mg ozone/g manure slurry. The PCR study revealed that the band intensity of the tetM gene gradually decreased by increasing the Fenton reagent and the applied ozone dose. However, significantly high doses of oxidants would be required to completely eliminate bacterial pollution in manure.

Simultaneous removal of oxytetracycline and sulfamethazine antibacterials from animal waste by chemical oxidation processes.

Simultaneous degradation of oxytetracycline (OTC) and sulfamethazine (SMZ) antibacterials in synthetically contaminated cow manure (20 mg of antibacterials/kg of manure) in the presence and absence of bedding was investigated by the application of ozone, Fenton, and persulfate oxidation processes. Almost the complete removal of antibacterials was attained with all oxidation processes, which were combined with a pretreatment of manure with magnesium (Mg(2+)) salt desorption. Among the investigated oxidation processes, thermally activated persulfate oxidation with 25 mM Na(2)S(2)O(8) at 50 degrees C was also applied to the animal feeding operations wastewater, and the pseudo-first-order degradation rate constants of OTC and SMZ were found as 3.22 and 1.25 (1/h), respectively. Thermally activated persulfate treatment resulted in the reduction of 82% inhibition of OTC and SMZ to 7%, indicating the production of almost nontoxic degradation products in the wastewater.

Comparison of the ozonation and Fenton process performances for the treatment of antibiotic containing manure.

An integrated treatment method based on magnesium salt extraction followed by chemical oxidation was used for the treatment of a veterinary antibiotic, oxytetracycline (OTC) contaminated cow manure since animal manure can be an important source for antibiotic pollution in the environment. Pretreatment with magnesium salt enhanced the efficiencies of subsequent oxidation processes by extracting 63.9% of OTC from the manure thereby making it more favorable for oxidation with the hydroxyl radicals produced by the Fenton and ozone oxidation processes. Both the 24 h Fenton oxidation process with 434 mM H(2)O(2) and 43.4 mM Fe(2+) doses and the 1-h ozonation process with an applied ozone dose of 2.5 mg min(-1) provided more than 90% OTC removal from the manure slurry. However, the second-order OTC removal rate constant of Fenton process (119 M(-1)s(-1)) was remarkably lower than that obtained with the ozonation process (548 M(-1)s(-1)). The oxidant dose was a significant factor for the efficiency of the Fenton treatment but not for the ozone treatment. The efficiencies of both the Fenton and ozone oxidation processes were not affected by the pH adjustment of the manure slurry.