Effect Of Inoculation Of A High Temperature-Resistant Bacterium And Thermophilic Composting On The Removal Of Fluoroquinolones In Broiler Manures

Fluoroquinolones (FQs) have been widely used in livestock and poultry breeding industry. High proportion of FQs residues in livestock manures may pose a serious threat to ecological environment and human health. FQs including Norfloxacin, Ciprofloxacin, Lomefloxacin, Enrofloxacin, and Sarafloxacin were taken as examples to discuss residue problems in livestock manures. Removal efficiency of FQs during composting was studied at different spiked concentrations through high temperature composting and inoculation of a high temperature resistant bacterium, which were divided into six treatments:T0, T15, T30, T60, T15+B and T30+B. The potential of high temperature composting was assessed for the removal of FQs. The effect of inoculation of a high temperature resistant bacterium on the removal of FQs was also discussed, the tendency of physicochemical properties such as temperature, pH, electrical conductivity, moisture content and seed germination index on elimination of FQs in manure were conducted in the paper. The results were as follows:(1) High temperature composting had a high potential in FQs removal in chicken manures after 42-day composting, with a relatively high degradation rate in early stage of composting (0-14 d) and highest removal efficiency of T15. The degradation of FQs in composting fitted the first order kinetics equation and the degradation rate at different initial FQs concentrations was T60>T30>T15. FQs reduced in each treatments over time, which indicated that high temperature composting took effect into elimination of FQs in chicken manures.(2) The removal rates of FQs (norfloxacin, ciprofloxacin, lomefloxacin, enrofloxacin and sarafloxacin) were 60.3%-76.4% in group T15+B under the treatment of inoculation of high temperature resistant bacterial, which were higher than those under the treatment of without inoculation by 3.3%-7.2%. However, the increase of the removal rates showed to be significant only for norfloxacin and lomefloxacin. The removal rates of FQs were 59.10%-83.14% in group T30+B under the treatment of inoculation of high temperature resistant bacterial, which had no big significant difference with those under the treatment of without inoculation. This indicated that the bacterium had little effect on removal efficiency of FQs at high concentration because bacterium activities may be influenced by high concentration of FQs.(3) Temperature, pH, electrical conductivity and moisture content were at their optimum level, which needn't be adjusted. Seed germination index was bigger than 80% at the end of composting process.The results showed that high temperature composting could be used in elimination of FQs in manures, however, additional efforts including the improvement of composting process and bacterial inoculation need to be taken in order to improve the FQs removal.