| Today, a variety of growth-promoting additives have been used widely inlarge-scale livestock and poultry industry. Most of these additives are excreted inthe form of their original products and enter the environment through a variety ofways. This will bring risks to the ecology of the environment. In this study, theadsorption of tetracycline and roxarsone by anaerobic granular sludge and thetransformation of carbadox in the composting were investigated. The mainconclusions were obtained as follows:(1) Adsorption of tetracycline by anaerobic granular sludge was investigated.The results showed that the adsorption of tetracycline by anaerobic granular sludgewas divided into two stages, the early stage of the fast adsorption and the laterstage of the slow absorption. Fast adsorption was mainly for the outer particleadsorption, while later adsorption was happened from out-surface to the internal inthe particle. The isotherm was fit well with the Langmuir equation. Theadsorption was a spontaneous and endothermic process.(2) Competitive adsorption of tetracycline and roxarsone by anaerobicgranular sludge was investigated. The results showed that the adsorption removal oftetracycline and roxarsone were efficient by anaerobic granular sludge. Theadsorption isotherm of roxarsone was fit well with the Langmuir equation, whilethat of tetracycline was fit well with the Freundlich equation. The adsorptionkinetics of tetracycline can be well described by second-order equation. Adsorptionof roxarsone and tetracycline by anaerobic granular sludge were spontaneous andendothermic process.(3) The degradation and transformation of carbadox in the aerobic compostingprocess was investigated. The results showed that the half-life of carbadox wasapproximately18d,10d and19d as C/N at15,25and40, respectively. There wasno obvious influence on the moisture content, pH, total nitrogen and solublephosphorus content with or without carbadox addition. |
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