| Antibiotics were been widely used in the treatment of human infectious diseases, animal husbandry and aquaculture as one of the most important medical discoveries. It produces a large amount of antibiotic activated excess sludge during the wastewater treatment of antibiotic production process, currently on sludge treatment and disposal does not have such a clear way. So the antibiotic residual sludge for further promotion of excess sludge recycling application has important research significance.The antibiotic activated excess sludge was characterized by SEM, element analysis TGA and BET techniques. The characterization of the sludge demonstrated mounts of remaining hypha residues existed in sludge and constructed to form porous structure, the specific surface area was 11.916 m2/g. The sludge contained a lot of organic material, main material proportion is: C(34%), H(10%), N(6%) and S(0.06%). The characteristics of the sludge provided favorable conditions for the adsorption of heavy metal ions.The static absorption experiments were carried out to study the influence factors,isotherm, kinetic and thermodynamics during the adsorption. The optimum quantity of antibiotic sludge were 1.0, 1.7 and 2.0 g, optimum p H range from 6 to 7, the equilibrium time was 90 min in the solution(50 ml、100 mg/L) of Cu2 + and Ni2 + and Cd2 +. The equilibrium data was fitting for Langmuir isotherm, and the maximum adsorption capacities were 18.484,14.837 and 9.116 mg/g for Cu2+,Ni2+ and Cd2+,respectively. The kinetic data of adsorption were described by a pseudo-second-order equation, indicating chemical adsorption. The thermodynamics study indicated the spontaneous and endothermic nature of the adsorption.The quantity of Ca2+ and Mg2+ released into solution were close equal to both Cu2+, Ni2+ and Cd2+ adsorbed indicated that the mechanism of whole metal removal process can be explained by ion exchange.The dynamic experiments were carried out to study continuous adsorption capacity of antibiotic activated excess sludge.In the single metal adsorption experiments, the efficiency of Cu2+, Ni2+ and Cd2+ were 86.4%, 83.3% and 68.3% respectively during the first round reaction. After the second round of the reaction, the adsorption efficiency had significantly decreased the adsorption efficiency of Cu2+, Ni2+ and Cd2+ were 74.8%, 73.2%and 48.0%, respectively. After the end of the third round of the reaction, the adsorption efficiency of Cu2+, Ni2+ and Cd2+ were 63.4%, 62.2% and 33.3% respectively. The maximum adsorption capacities were 112.7,109.0,73.6mg/g for Cu2+, Ni2+ and Cd2+, respectively. The sludge can recycled 2-3 round according to different metal ions. The changed of water quality in the experiment can be concluded that the sludge in the reaction to release less COD. The turbidity and chromaticity became smaller and increased with reaction.The paper studied the influence of antibiotic activated excess sludge during adsorption for environment.The sludge leaching liquid didn’t inhibite Scenedesmus obliquus and the 502 luminescent bacteria, which proved the sludge had a little poison in a certain concentration range, but almost no toxicity in low concentration. The toxicity grade was Ⅰ(slightly toxic).There were 39.32 and 1367.12μg/g oxytetracycline and tetracycline in the antibiotics wastewater excess active sludge and it released 1.12 and 13.883 μg /g oxytetracycline and tetracycline after 2 hours leaching, then increased to 1.96 and 20.834μg/g after 24 hours. After drying at 250 ℃ the oxytetracyline and tetracycline were 0.269 and 2.459μg/g to 0.371 and2.912μg/g after 2 hours and 24 hours respectively. Measured sulfa(sul1 and sul2) and tetracycline(tetq, tetw and teto) resistance genes in the sludge leaching liquid, the concentrations of sulfa antibiotics resistance genes(the range between 109-106copies/m L)were higher than tetracycline resistance genes(the range between 108-104 copies/m L).High temperature and heavy metal ion can reduce the release of resistance genes. |
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