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Background: Hospital wastewater usually contains pathogenic micro-organisms, drugs, radio active materials, and toxic chemical elements that in case of being disposed without filtration, will result in pollution and spread of diseases. Therefore, evaluating the status of wastewater disposal in hospitals is necessary for proper planning. Materials and Methods: In a cross-sectional descriptive study in 2008, data collection was done by means of interviews, observations, and questionnaires in all hospitals of Markazi Province. Noticing the 33 items in the questionnaire, the overall conditions of the hospitals and the methods of using the sewage system were studied, and at the same time, filtration installations and wastewater disposal systems were inspected. Results: Of all the 19 hospitals, 10 used a conventional method of direct disposal of sewage to subterranean shafts, and of the 4 hospitals with filtration installations, three were practically out of order or were not efficient. Five of the hospitals were directly linked to the city sewage system without any pre-filtration. None of the hospitals had a specialized operator of sewage filtration and disposal system. Conclusion: Wastewater disposal in hospitals of Markazi Province is not desirable therefore, such acts as conducting more specific surveys, creating a positive attitude in planners, and providing sufficient funds for filtering wastewater in some of the hospitals are suggested.

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Background: The presence of nitrate in drinking water causes various health and environmental problems. The aim of this study was to evaluate the efficacy of nitrate reduction by Fe/H2O2 process and adsorption on activated carbon. Materials and Methods: This experimental study investigated nitrate oxidation by advanced oxidation process of Fe°/FeІІ/FeШ/H2O2 at pH 2-10, nitrate concentrations of 50-300 mg/L. After adjusting the pH, 0.5, 1, 2, 5, and 10 g/L values of GAC, PAC, H2O2/GAC, and Fe/H2O2/GAC together with H2O2 at retention times of 15, 30, 45, 60, and 90 minutes, respectively, were added and mixed. Results: At retention time of 10 minutes and 0.5 mL H2O2 and 1 g/L from Fe°, FeІІ, and FeІІІ, the removal efficacy was 88.5, 84 and 78%, respectively. At 50 mg/L nitrate and 0.5, 1, and 10 mg/L GAC concentrations, the removal efficacy was 56.5, 93.6, and 82.6%, respectively. The nitrate removal efficiency at pH=4 was approximately 50%, whereas at pH=3 with 30% efficacy, it increased to 80%. Conclusion: Modified Fe/H2O2 process with iron nano-particles and activated carbon adsorption can effectively reduce nitrate under optimal conditions. The use of activated carbon at a concentration of 1 g/L increased the removal efficiency of nitrate to 90%.

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Background: Today, global concerns about water pollution with chemicals and its adverse impact on health have increased. This study aims to evaluate the physical and chemical quality of water treated through domestic water treatment systems.

Materials and Methods: In this cross-sectional descriptive study, water samples were collected from 60 domestic water treatment systems and parameters, such as turbidity, total dissolved and suspended solid, total hardness and calcium, magnesium hardness, alkalinity, total alkalinity, carbonate, bicarbonate, nitrate, sulfate, nitrite and fluoride, EC, pH, and free chlorine residuals, were examined.

Results: The results indicate that the average concentration of chemical parameters in treated water were: chloride=0.1mg/L, nitrate=0.006mg/l, sulfate=5 mg/l, Nitrate=15mg/L, bicarbonate=49 mg/L, calcium hardness=18 mg/L, and fluoride=0 mg/l.

Conclusion: The overall results of this study indicated that the use of municipal water treatment reduced Cl2, sulfate, and bicarbonate concentrations than the optimal levels in urban areas water. However, nitrite concentration was significantly higher in the output of these systems than distribution systems, which is a source of concern.

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Background: Naphthalene is a polyaromatic hydrocarbon (PAH_s) present in many water sediments. This study evaluated the performance of UV/H₂O₂ reaction to decompose naphthalene in the aqueous solution.

Materials and Methods: It was an experimental-laboratory study. A one liter cylindrical glass reactor was used for performing all degradation experiments. The radiation source was a low pressure mercury UV lamp emitting at 254 nm (30 W, UV-C) which was placed above a batch photoreactor for UV/H₂O₂ experiments and different concentrations of H₂O₂ (5, 10, 15, 20, 25 and 30 mg/L) were tested.

Results: In 15 mg/L naphthalene in UV/H₂O₂ system and reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 15, 28, 31 , 36, 42, 52, 56, 73 and 59.5% naphthalene removal efficiencies were observed and COD removal efficiencies in reaction times 5, 10, 20, 30, 40, 50, 60, 100 and 120 minutes, 22, 38, 45, 61.5, 67.5, 70, 80, 88.5 and 76 % were observed. When the initial pH values were 3, 4, 5, 6, 7,9, 10 and 12 the naphthalene removal efficiency was approximately 75.8, 63.4, 62, 58.5, 44.8, 35.8 and 30%, respectively, with UV/H₂O₂ system.

Conclusion: The experimental results of this study suggested that the dosages with 20 mg/L H₂O₂ at pH= 3 with 2.8 W/cm² UV intensity (254 nm) provided the optimal operation conditions for the mineralization of naphthalene yielding a 73% mineralization efficiency after 100 minutes of reaction time.