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BackgroundAntibiotics have been increasingly used for veterinary and medical purposes. The overuse of these compounds for these purposes can pollute the environment, water resources in particular. Tetracycline, among other forms of antibiotics, is one of the most applied antibiotic in aquaculture and veterinary medicine. The present study aimed to tack the traces of tetracycline in the effluents of municipal and hospital wastewater treatment plants, surface and groundwater resources and finally the drinking water provided from these water resources.MethodsThe samples were taken from Fasha-Foyeh Dam, wells located at Varamin Plain, and Yaftabad; and also, wastewater samples were collected from the wastewater treatment plant effluents of Emam Khomeini Hospital and a municipal wastewater treatment plant which its effluent is being released to the surface water of the area covered in this work. 24 samples were collected in total during July 2012 to December 2012. The prepared samples were analyzed using high-performance liquid chromatography.ResultsBased on the results, mean tetracycline levels in surface and ground water at nearby of animal farms was found to vary from 5.4 to 8.1 ng L-1. Furthermore, the maximum TC concentration of 9.3 ng L-1 was found to be at Yaft-Abad sampling station. Although tetracycline traces could not be detected in any investigated Hospital WWTP effluents, it was tracked in MWWTP effluent samples, in the concentration range of 280 to 540 ng l−1.ConclusionThe results showed that the concentration of TC in water resource near the animal farms is higher than the other sampling stations. This is related to the usage of antibiotic for animals. In fact, it caused the contamination of water resources and could contribute to radical changes in the ecology of these regions.

BACKGROUND: In the present work, Hg (II) is considered as one of the most dangerous elements being released excessively into the environment from various sources. Therefore, the aim of this study is the removal of Hg (II) from wastewater effluent by synthesizing a magnetic chitosan modified with glutaraldehyde (MCS-GA) as an adsorbent. The composite structure was characterized using SEM/EDAX, FTIR, and XRD techniques. The adsorbent was tested by a batch system to determine the optimum conditions for removing Hg (II) under real conditions. RESULTS: The results showed that 0.5% GA effectively enhanced the removal efficiency. The maximum adsorption capacity of MCS-GA was 96 mg g −1 at pH 5.0 and 25 ∘ C. The adsorption isotherm data obeyed the Langmuir model (R 2 >0.981) and pseudo-second-order (R 2 >0.996) kinetic models. It was also found that Hg (II) adsorption on MCS-GA is inherently exothermic and occurs spontaneously. The reusability of MCS-GA was approved over 12 sequential cycles of adsorption-desorption. ANOVA analysis showed that the contact time has a synergistic effect on Hg (II) removal, whereas pH and initial concentration have antagonistic effects. CONCLUSION: Overall, the synthesized adsorbent was able to remove Hg (II) efficiently under both experimental and real conditions.