Effect of Temperature and Metal Ions on Degradation of Oxytetracycline in Different Matrices

Composting is widely applied in animal manure treatment and reclamation. The degradation of organic pollutants during the composting treatment is attributed to two parallel processes: one is the bioprocess induced by the used microorganisms, and the other is the chemical process. In order to clarify the relative contribution of the chemical process to the compositing, in this paper, oxytetracycline (OTC) was chosen to study the degradation of tetracyclines (TCs) in water and chicken manure. It was observed that the degradation of OTC in water was much faster than that in chicken mature. At 40 ̊C, 95% of OTC in water could be removed in two days, while it took about one month in mature. By increasing the temperature to 50 ̊C, 60 ̊C and 70 ̊C, the required degradation time (with the degradation efficiency more than 95%) was shortened to 22, 13 and 9 days, respectively. This difference was caused by desorption hysteresis and irreversible fixation due to the formation of complexes of OTC with co-existed metal ions in the matrix. It was found that the coexisted Ca2+, Zn2+ and Ni2+ ions decreased the degradation of OTC, whereas Cu2+ ions promoted the degradation of OTC.