| Over the last decade, with the development of science and medical technology, the demands and utilities of pharmaceutical active compounds(PHACs) for human beings has been rising rapidly. What’s more, pharmaceuticals abusion is found elsewhere. Large amounts of PHACs and their metabolites are detected in surface water, ground water and wastewater frequently. Although these compounds present at concentration up to μg-ng/L level, can be absorbed in the tissues of animals and humans and accumulate in the living bodies. In some extent, they migrate and enrich through food chain, affecting the normal metabolism and reproduction of the organism, finally result in potentially adverse effects on the organism. Activated carbon adsorption method is simple and relatively cost-effective, which wouldn’t generate undesirable by-products and was found to be superior to other processes in terms of simplicity of design and operation. However, adsorption of multiple pharmaceuticals is scarce, so as the adsorption in wastewater. Therefore, it is considerably important to study the adsorption of multiple pharmaceuticals in wastewater effluent on activated carbon.In this research, four PHACs such as clofibric acid, carbamazepine, naproxen and diclofenac, which detected from wastewater treatment plant in Xi’an, are investigated. Firstly, the adsorbent in this research is selected through batch experiment, the time of adsorption, the dosage of activated carbon, competitive effect on the adsorption are studied. The adsorption mechanisms are also explored. Secondly, the adsorption removal of PHACs on different particle size of activated carbon by dynamic experiment is discussed, at the same time, dynamic breakthrough curves are drawn, choosing the best particle size of activated carbon.The results show that coconut-shell based activated carbon is found to be the experimental adsorbent prior to charcoal activated carbon. When determining their equilibrium at carbon dosage of 133 mg/L, it is found that the adsorption capacity of clofibric acid, carbamazepine, naproxen and diclofenac are 2.48mg/g, 3.0mg/g, 2.74mg/g and 2.52mg/g, respectively. All bottles are sealed and shaken at 150 rpm at 25℃.The adsorption of pharmaceutical on coconut-shell based activated carbon is in the order of CBZ > NAP > DCF > CA, and can be described by pseudo-second-order kinetic model and Friendlich isotherm model. The adsorption rate is influenced by intrapartical diffusion and film diffusion. There is an obvious difference in adsorption affinity among the target pharmaceutical compounds. Compared with the adsorption in ultrapure water solution, the adsorption capacity in the secondary effluent from wastewater treatment plant is decreased sharply, which is related to the impact of competitive adsorption by background organic compounds and inorganic salts in wastewater. It is turned out that dissolved organic matter in sewage removed by the activated carbon while at the same time reducing the ability to remove pharmaceutical compounds. The penetrate time of different particle diameter of activated carbon is different. The smaller the particle diameter is, the longer penetrate time is and the stronger adsorption affinity is. However, if the particle diameter is too small, the activated carbon is easily blogging. Thus, the diameter between 1~2mm is selected to be the best of all tested activated carbons.According to the results in this research, granular activated carbon can effectively remove pharmaceuticals in aqueous, which provides a theoretical foundation in adsorption of pharmaceuticals in sewage. However, desalination should be made for the practical application of adsorption technology. |
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