Physico-chemical Treatments Of Several Typical Anticoccidial Veterinary Drugs In Wastewater

Anticoccidial veterinary drugs are widely used in broiler and swine industries. The amount of applied dosage is quite large and most of the added antibiotics were excreted into manure and wastewaters with faeces, which led to the pollution of soil and water. In this thesis, the physico-chemical treatments of several typical anticoccidial veterinary drugs in wastewater were investigated. The following conclusions were obtained:(1) Firstly, the adsorption characteristics of 4-hydroxy-3-aminophenylarsonic acid (HAPA) on anaerobic granular sludg (AGS) were studied. The results showed that the quilibrium state of the adsorption was reached at about 10 h, and the adsorption data fitted well with Freundlich and DR models. The maximum adsorption capacity of HAPA onto AGS was 12.57mg/g,25.05mg/g and 26.31mg/g at 15℃,25℃ and 35℃, respectively. The process was mainly a physical adsorption process, and the intra-particle diffusion was the rate-limiting step. Rising pH and phosphate ions had negative effects on the HAPA adsorption. The adsorption was spontaneous and endothermic process.(2) Secondly, the degradation of sodium sulfaquinoxaline through electro-catalytic way was investigated. After six days treatment, the degradation rate of sodium sulfaquinoxaline reached above 90%. The reaction kinetic was pseudo-first-order. When the applied voltage was 2.0 V, the efficency of degradation after 6 days was more than 95% and energy consumption was low. Low initial concentration of sodium sulfaquinoxalinum and high voltage promoted the degradation efficency.(3) Thirdly, the oxidation of 3,5-dinitrobenzamide with sodium hypochlorite in aqueoussolution was studied. The results indicated that the whole oxidation process was a second-order kinetic reaction. The reaction rate increased with the incease of the oxidizing agent concentration. When the ratio of sodium hypochlorite to 3,5-dinitrobenzamide was greater than 20, the reaction rate was less affected. The solution pH had a significant effect on the degradation. At pH ranging from 5 to 8, the degradation efficiency increased with the increase of pH. The presence of ammonium ions and humic acids inhibited the degradation of 3,5- dinitrobenzamide.