نشریه مهندسی بهداشت محیط
سال هفتم شماره 4 (پیاپی 29، تابستان 1399)

The presence of nitrate and phosphate in concentrations above the allowable level in surface and groundwater resources leads to disease and problems. The aim of this study was to investigate the adsorption efficiency of magnetic-metallic chitosan nanocomposite in the adsorption of nitrate and phosphate from aqueous solutions.

The adsorbent was synthesized by co-precipitation method. Different concentrations of nitrate (50-300 mg/L) and phosphate (100-400 mg/L) were prepared and their removal was evaluated by different concentrations of synthesized adsorbent (0.1-0.5 g/L). Various parameters such as temperature (20-40 ° C), pH (5-8), contact time (0-90 minutes) and the presence of interfering ions (chloride, phosphate, hardness 1.5 mM) were investigated. SEM, XRD, FTIR and XRF tests were used to determine the synthesized adsorbent characteristics.

Magnetic-metallic chitosan nanocomposite adsorbent is able to effectively remove nitrate and phosphate from aqueous solutions. Nitrate and phosphate removal efficiencies under conditions of  pH=5, nitrate concentration (100 mg/L), phosphate concentration (200 mg/L), 60 min contact time and 0.3 g/L adsorbent concentration were 87.2% and 74.9%, respectively. The adsorption process of both pollutants followed the langmuir model and pseudo second kinetic order. Interfering ions reduced the removal efficiency of contaminants by 73.1% for nitrate and 65.9% for phosphate.

Since the presence of nitrate and phosphate anions, as common contaminants and indicators of water resources, the use of magnetic-metallic chitosan nanocomposite adsorbent is very effective in the removal of these contaminants.

Antibiotics are considered among the pollutants in water environments with stable effects. This study aimed to investigate the efficiency of photocatalytic process using core-shell TiO2 under ultraviolet radiation for the removal of Cefixime antibiotic from aqueous solutions.

This study was conducted in an experimental-laboratory scale. The effect of factors such as pH (5, 6, 7, 8 and 9), initial concentrations of Cefixime (2-10 mg/L) and concentrations of catalyst (0.5-5 g/L) was surveyed. Sample volume for every step of the experiments was 1000 ml. A batch stainless steel 3L photo catalytic reactor was designed. The synthesized catalyst was characterized by SEM ، XRD and VSM Methods.

Physical characteristics of the Fe3O4/SiO2/TiO2 revealed that the catalyst particles had the average size of 10 nm. The photocatalytic degradation of Cefixime with UV+ Fe3O4/SiO2/TiO2 in the optimal condition was 100% (pH =6, retention time= 25 min, Cefixime concenteration= 2 mg/L catalyst dosage= 4 g/L). Synthetic models showed that the process of photocatalytic removal of Cefixime followed the first-order model.

The results of this study suggested that UV+ Fe3O4/SiO2/TiO2 process is very effective method for the complete removal of Cefixime antibiotic from aqueous solutions.

Application of air quality models in Health Risk Assessment system has been defined as an effective tool in assess the human population exposure to environmental harmful factors. The present study was conducted to aim of health risk assessment of respiratory exposure to PM10 Emitted from Depos of primary materials and waste a number of Non-metallic minerals industries by Modeling method.

In this descriptive study, first to Field visits and laboratory measurements was obtained the information needed for SWEEP model to estimate PM10 emission rate from depos of Tile and Ceramic, Khak-e-chini and glass industries. Then, with the introduction of meteorological information to AERMET, the digital elevation model to AERMAP, the emission rate and the geometric dimensions of the pollutant sources to AERMOD, simulated the values of exposure to PM10 in the affected population. The chemical composition of the depos was determined using ICP-MS. Subsequently, using the EPA suggested relationships was estimated the risk of carcinogenic and non-carcinogenic exposure to PM10.

According to the simulation results of SWEEP model, the highest PM10 emission was estimated for the Tile and Ceramic depo. The highest concentration maximum of 1, 8, and 24 h of PM10 simulated were 8840, 1967, and 1272 µg/m3, respectively. The highest average respiratory exposure of 1 (52.53), 8 (11.64), 24 (5.85 µg/m3) hour to PM10 was estimated for Sand and Gravel processing plant staff. The highest percentage of chemical compounds in depos was for silica. Accordingly, the carcinogenicity risk (ILCR) of exposure to PM10 was predicted less than 10-4 and non- carcinogenicity risk (HQ) less than one.

Although numerical values of risk were predicted in the permissible limit, but to creating Surface rock on the depo industries can reduce the emission of PM10.

Nowadays, since increasing environmental pollution particularly soil contamination can cause adverse health effects, kind of methods such as phytoremediation techniques are commonly used to remediate organic, inorganic and nuclear pollutants from contaminated sites. Therefore, this study was conducted to assess of chelating agents with different biodegradability rates on the enhanced phytoremediation efficiency of Amaranthus caudatus and Tagetes patula as ornamental species in cadmium contaminated soils in 2018.

In pot experiments, the soil specimens were moderately artificially contaminated by cadmium chloride (50 and 100 mg/kg).            Then 2.5 mmol/kg of EDTA, 2.0 mmol/kg of salicylic acid (SA) and 2.5 mmol/kg of citric acid (CA) solution were added to the contaminated soils to study the influence of these chelating agents on phytoremediation efficiency by studied ornamental plants. Finally, after acid digestion of cultivated soil, roots and stems of A. caudatus and T. patula, the Cd content was determined using ICP-OES.

The results showed that after 60 days of pots irrigation, the maximum mean content of Cd (mg/kg) in cultivated soil, root and stem samples of A. caudatus with 1.87, 4.50 and 1.89 were found in the SA, EDTA and SA treatments, respectively. Moreover, the maximum mean content of Cd in cultivated soil, root and stem samples of T. patula with 1.86, 1.18 and 3.10 were found in the control, CA and SA treatments, respectively. Also, the values of translocation and bioconcentration factors indicate that A. patula can be considered to be potential plant species for phytostabilization and phytoextraction of cadmium, respectively.

The results reported in this study show that the organic acids such as SA and CA have considerable role in soil refining electrokinetic or enhance of soil electrokinetic bioremediation through mechanisms resembling hormonelike effects, phosphate  release and dissolution, enhancing of cadmium mobility and some enzymatic activities, microstructural variations and retention capacity decreasing of clay particles. Therefore, due to the desirable effects of organic acids as chelate agents to enhancing phytoremediation efficiency of hyperaccumulator species use of these compounds in the cleanup of contaminated soil is recommended.

The management of healthcare wastes is receiving greater attention because of the risks to both human health and the environment caused by inadequate waste management practices. In that context, the objective of this study was to investigate the hospital solid waste management in Kermanshah city, Kermanshah province, Iran based on Ministry of Health and Medical Education checklist which is related to environmental health of hospitals.

This study (qualitative-quantitative) was performed in two interval time in two consecutive years through a valid checklist of waste management process of Iranian Ministry of Health which include all steps of medical waste management. The quantity of hospital waste produced was measured during one week in autumn session during study interval. 

The results of this study showed that the total averages of desirability in waste management compared to health standards in Kermanshah city hospitals were 70.38 ± 15.5 and 74.3 ± 14.8 in 2015 and 2016, respectively. The average desirability of waste management in governmental, military, private and social hospitals improved from 61 to 65.14, 75 to 79, 87 to 90 and 84.5 to 86%, respectively in two years of study interval. The average (weighted mean) of total hospital wastes generation rate (in Kermanshah city) was 4.06 kg/bed-day and for governmental, military, private and social hospitals were 4.69, 3.26, 2.7 and 1.62 kg/bed-day, respectively. The results indicated that there was a significant correlation (p < 0.05) between hospital active bed and medical wastes production.

From the results of this study, the score of waste management practices in Kermanshah hospitals are evaluated as moderate. Therefore, more efforts, monitoring and control should be implied to achieve the desired state of hospital waste management

Nowadays, due to the conventional methods of landfilling, the environmental concerns about generated leachate are becoming a global problem. Physical-chemical process is considered a potential and cost-effective solution for the treatment of municipal landfill leachate. Since jar-test are time-consuming experiments for obtaining the appropriate concentration of coagulants, the aim of this research was the treatment of landfill leachate using response surface methodology as a substitute for conventional methods in coagulation–flocculation process.

Experiments were performed in a six-cell jar-test with effective volume of 500 mL. The ability of Ferric chloride hexahydrate to response to four parameters including COD, TSS, alkalinity and turbidity was investigated. To evaluate the model and optimization of coagulant concentration and pH, central composite design and response surface methodology were used due to the highest removal efficiency. Physical and chemical analyses were performed based on standard methods for the examination of water and wastewater.

The results showed that the quadratic model was achived for the three responses (COD, TSS and alkalinity) and the Reduced Quadratic model was obtained for Turbidity under the optimum conditions for the concentration of 10.23g/L at pH 8.85. Verification experiments, under optimum conditions in removal of COD, TSS, turbidity and alkalinity resulted 66.79%, 88.61%, 97.53% and 67.89%, respectively. Statistical studies (ANOVA table, the amounts of R2 and P-value) showed that the models were suitable for providing experimental data and in all models, the R2 value was greater than 0.99. P-value values also showed that the effects of quadratic model and reduced quadratic model were significant in ferric choloride dosage and coagulation pH. These experimental results were consistent with those predicted by the model.

According to the obtained results by response surface methodology, coagulation–flocculation process can be used as the effective process to remove leachate inhibitors.

Ibuprofen is one of the most widely used non-steroidal anti-inflammatory drugs that enter the water resources through manufacturing plants and disposal of hospital effluents and even domestic wastewater. The aim of this study was to removal of ibuprofen using biodegradation process by Saccharomyces Cerevisiae yeast fixed on alginate substrate from aqueous solutions.

This research was an experimental-laboratory study. The effect of parameters including yeast concentration (0.1-0.3 g/100ml), Initial concentration of ibuprofen (50-350 mg/l), contact time (1-30 hours),  initial pH (4-7) on the biodegradation of ibuprofen with stabilized yeast on alginate substrate was investigated. Experiments were designed and optimized using response surface methodology in Design Expert 7 software.

The findings of this study showed that the maximum removal of ibuprofen by fixed yeast on alginate at pH = 5.5, yeast concentration 0.2 (g /100ml), time 30 hours, and initial concentration of ibuprofen=50 mg/L was 93.5%.

Based on the results of this study, it can be concluded that the fixed Saccharomyces cerevisiae is capable to biodegradation of ibuprofen at low cost and high efficiency and this cost-effective method can be used for the treatment of pharmaceutical wastewater.

Today chr('39')s World is faced with the environmental problems associated with heavy metal contamination as one of the main issues of concern. Mercury, known as one of the most toxic heavy metals, has gained a lot of attention due to its sustainability and bioaccumulation in the food chain as well as having detrimental health problems such as kidney failure and gastrointestinal damages. This study is centered on the removal of Hg (II) ions from aqueous solutions using a magnetite/biosilica/sodium alginate nanocomposite as an efficient adsorbent.

Within this study, the magnetite/biosilica/sodium alginate nanocomposite was successfully synthesized via a co-precipitation method. The structure and morphology of the prepared adsorbent were confirmed by SEM, XRD and VSM analyses. The parameters affecting the adsorption process such as pH, contact time, adsorbent amount, temperature and initial concentration of Hg (II) ions were all evaluated.

The optimum conditions obtained were as follows: pH 5, adsorbent dosage 0.2 g/L, contact time 80 min, temperature 45 °C. The results revealed that the removal efficiency dropped by increasing Hg(II) concentration. The adsorption of Hg (II) obeyed the Langmuir isotherm (R2 0.9998) and pseudo-second kinetic model (R2 0.9997). Additionally, the thermodynamic studies demonstrated that the adsorption process is of endothermic and spontaneous nature.

All in all, the synthesized adsorbent was applied for the removal of Hg (II) ions from the aquatic environment. Ease of separation from the aqueous solution due to its magnetic properties as well as high level of Hg (II) recovery are amongst the unique feature of the adsorbent.