The Study Of Removal Of Tetracycline Antibiotics(TCs)in The Activated Sludge Treatment System

The pollution of antibiotics had become one of the hot topics in environment domain. Tetracycline antibiotics (TCs) was widely used in the treatment of infectious disease in human and animal as one of the most common antibiotics, and sometimes used as animal growth promoting agent in animal husbandry. In recent years, a certain concentration of residual antibiotics tetracycline antibiotics were detected in various environmental media such as surface water, soil etc, continuous exposure and synergistic reaction of multiple antibiotics will induce the emergence of resistant bacteria even though the detection of concentration is not high, resulting in adverse effects on the ecological system. Activated sludge process was extremely significant to the removal of tetracycline antibiotics as the common municipal sewage treatment. So far the reports of the removal effect of tetracyclines were mostly based on field sampling witch was uncertain, so the removal tate was diversifying, sometimes negative removal rate was even a minus. Therefore, it was necessary to determine the actual removal rate of tetracycline antibiotics in activated sludge by the running parameters of laboratory research that can be precisely controlled in order to overcome the uncertainty of field sampling. The main researches were as follows:(1) The removal pathways of three kinds of tetracycline antibiotics in the activated sludge process were proved. Generally, the removal pathways of antibiotics in the activated sludge process include biological degradation, adsorption, hydrolysis and volatile. Tetracycline antibiotics were mainly removed by adsorption in the activated sludge process, while, small amount of biological degradation was exist in the process that chlortetracycline(CTC) was removed, but oxytetracycline(OTC) and tetracycline(TCN) were hardly biodegradable. The three kinds of antibiotics was fast absorbed to the surface of activated sludge at the beginning of reaction, then the adsorption equilibrium achieved and concentrations in the solid phase and liquid phase became stable.(2) Batch experiment was used to study the adsorption behavior of activated sludge on three kinds of tetracycline antibiotics in different experimental conditions since the removal pathways of three kinds of tetracycline antibiotics in the activated sludge process were dominated by adsorption. Sludge adsorption was a fast process. The time that adsorption equilibrium achieved of three kinds of TCs was as follows,TCN>CTC>OTC; Mixed liquid suspended solids (MLSS) had great effects on adsorption of three kinds of antibiotics, the total adsorption amount of three kinds of antibiotics increased with the increase of MLSS concentration, while the unit adsorption of the sludge decreases because of the solid concentration effect; The total removal rate of three kinds of antibiotics:OTC>TCN>CTC; The adsorption capacity of sludge on three kinds of antibiotics gradually decreases with the increase of pH value, and The removal rate of the three kinds of antibiotics in same pH conditions was always:OTC>TCN>CTC; three kinds of antibiotics could be fitted well by Freundlich model and linear distribution coefficient in the range of10-30℃...