نشریه مهندسی بهداشت محیط
سال نهم شماره 4 (پیاپی 37، تابستان 1401)

Recently, significant efforts have been performed for the removal of various emerging pollutants (EPs) from water sources. Among these EPs, benzotriazole has been widely identified in aquatic environments, which has harmful health and environmental effects, so it is necessary to apply various methods to remove it. Up to date, the use of advanced oxidation processes (AOPs) as an efficient method for the degradation and mineralization of EPs pollutants from aqueous solutions has attracted so much attention. Therefore, in this research, the performance of the persulfate activation process using magnetic nanocatalyst iron oxide-activated carbon prepared from coconut shell for the removal of benzotriazole from aqueous solution, and also the effect of different parameters have been investigated.

This research is an experimental-laboratory study. The effect of various variables such as solution pH (2-10), catalyst dose (0.1-0.5 g/L), persulfate concentration (1-5 mM), and initial concentration of benzotriazole (10-50 mg/L) was investigated. The final concentration of benzotriazole was measured using a spectrometer. Also, the characteristics of the synthesized catalyst were investigated using numerous analyzes such as BET, FESEM, XRD, EDX and VSM, and

The results showed that the highest efficiency of the process for the removal of benzotriazole was attained at pH: 6, initial concentration: 10 mg/L, catalyst dosage: 0.5 g/L, persulfate concentration: 3 mM, and more than 80% of benzotriazole was removed. On the other hand, the results of catalyst characterization showed that the catalyst was perfectly synthesized and could be reused in five consecutive cycles.

Based on the results of this research, this catalyst had a high performance for the removal of organic pollutants from aqueous solution.

: Site selection is an important and necessary issue in waste management especially in fast-growing regions. Due to the landfill is a common solution for the final disposal of municipal solid waste in Iran, this study was carried out for MSW landfill site selection of Songhor Township by combining the geographic information systems (GIS), the analytical hierarchy process (AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS).

In the current research, ArcGIS 10.2 software and its extensions were used as the GIS tool since there is able to perform suitability analysis using multi-criteria evaluation. Also, to identify appropriate landfill areas in the Songhor Township, eleven criteria including slope, geology, hydrology, fault, drainages, distance from transportation routes and rails, distance from protected areas, land use, population areas, distance from groundwater resources and distance from urban areas were evaluated. Then a final map was generated which identified the suitability regions for MSW landfill sites establishment.

Based on the results obtained, 4.2% of the study area was most suitable, 33% was suitable, 17.8% was poorly suitable, and 45% was unsuitable for sanitary disposal of solid wastes of Songhor Township.

Since the AHP has relative ease of handling multiple criteria, and on the other hand, has potential to easy understand and effective handling of both qualitative and quantitative parameters, therefore, use of AHP is suggested as an efficient method to prioritization of suitable areas for landfill site selection. In other words, the AHP is a powerful tool for solving complicated problems that may have interactions and correlations among multiple objectives.

Air pollution is one of the serious challenges that have been faced in recent years, especially in major cities around the world. Isfahan, as one of the metropolises of Iran, is no exception to this rule. This issue has become critical for Isfahan as a densely populated and industrial city.

In this research, the data recorded at 17 air quality monitoring stations in Isfahan have been analyzed. The stations included Ahmadabad, Parvin, Rudaki, Ostandari, Kharazi, Rehnan, Kaveh, Feiz, Mirzataher, Jey, Misaq Stadium, Farshadi, Bahonar, Enghelab, Shahinshahr, Mobarakeh and Segzai. All the statistical analyzes in this research were related to the AQI air quality index and were performed using Excel software.

The results showed that among the 17 studied stations, Ahmadabad station did not have any clean and good days during the studied period (From April 21, 2021 to March 20, 2022) and compared to other stations, the highest number of days with the condition Unsanitary is recorded at this station. It also had the highest AQI in the fall compared to other stations. Therefore, Ahmadabad station is the most polluted area in terms of air quality. The results also showed that the highest number of good and clean days was recorded in Mobarakeh and Shahinshahr stations. These two stations had the lowest amount of AQI during the study period.

The results of this study shows that areas such as Segzi and Mobarakeh, which are relatively industrial areas, have less pollution than the Ahmadabad area, which is a residential but with high traffic. Therefore, it can be concluded that the impact of pollution caused by cars in 2021-2022 was more than the pollution caused by industries.

UV and chlorination processes are widely used for wastewater and water disinfection. In recent years, they have been used integrative under the name of Advance oxidation process (AOP) method known as UV/chlorine process. In the UV/Cl process, Cl•, Cl2•−, and HO• radicals are produced during the process and are able to remove hard degradable pollutants. In this study, the effect of the simultaneous presence of bromide in the application of UV/Cl process to dye removal from textile wastewater and synthetic wastewater containing Direct Red 83:1 (DR83:1) is studied and investigated.

The wastewater used in this study was prepared from one of the textile units of Isfahan province. Operating parameters affecting the process including chlorine dose (0.2, 0.5, 1, 1.5 and 2 mmol), bromide dose (0.25, 1, 1.25 and 1.5 mmol) and Different initial pH values of textile industry wastewater (3, 5, 7, 8.3, and 11) were investigated to determine the optimal values of the process for dye removal. Also, the effect of the presence of bromide in the UV/Cl process in the degradation of DR83:1 from synthetic wastewater at different pH has been investigated (3, 5, 7, 9 and 11).

Based on the experiments, the results showed that in both wastewaters, the UV/Cl/Br process performs better in dye removal than the UV/Cl process. The most favorable performance of the UV/Cl/Br process for dye degradation from textile wastewater was achieved under the conditions of bromide dose equal to 1.25 mmol, chlorine dose equal to 1.5 mmol and the actual initial pH of the wastewater equal to 8.3 (dye removal efficiency equal to 92.04 %). The optimal performance of the UV/Cl/Br process in the degradation of DR83:1 from synthetic wastewater was obtained under the conditions of bromide dose of 5 mmol, chlorine dose of 0.1 mmol and pH of 3. The pH parameter was investigated in both wastewaters and the results showed that the optimal performance of the UV/Cl/Br process to remove dye from textile wastewater occurs in alkaline pHs, while the performance of the UV/Cl process to remove DR83:1 from synthetic wastewater in Acidic pHs is more favorable. The effect of different dosages of key parameters revealed that by increasing the dosage of bromine and chlorine, the performance of the system in dye removal efficiency does not improve.

The UV/Cl advanced oxidation process has a high potential to remove dye from wastewater, and the presence of bromide ion increases the efficiency of this system, which can be used as a stable and capable system in dye treatment from textile industry wastewater.

The presence of heavy metals in the environment and especially bioaccumulatioin of these compounds in tissues of aquatic organisms could constitute be a hazard to food security and public health. Therefore, this study was conducted to analysis of As, Pb and Cu contents in muscle tissue of Oncorhynchus mykiss and Barbus barbus captured from the Sirvan River, Kurdistan in 2019.

In this descriptive cross-sectional study, a total of 30 fish samples were collected randomizelly from five sampling stations along the Sirvan River. After samples preparation, As, Pb and Cu concentrations were determined using ICP–OES. Also, all statistical analyses of the obtained data were performed using SPSS software.

The results showed that the mean concentrations of As, Pb and Cu (µg/g, wet weight) in muscle tissue of Oncorhynchus mykiss were 0.022, 0.034, and 0.078, respectively, while in muscle tissue of Barbus barbus were found to be 0.018, 0.012 and 0.042, respectively. Also, the mean contents of all the analyzed elements were lower than maximum permissible concentration (MPC) established by FAO/WHO, ATSDR, FDA and EU.

Although at the time of this research the contribution to the total body burden of the analyzed elements can be considered as negligibly small, mismanagement of land uses around the Sirvan River could lead to the entry of several kinds of pollutants such as pesticides and potentially toxic elements into the water body. Consequently, adverse health effects could be occured for local consumers through ingestion of fishes with high accumulated heavy metals in their tissues.

Dust is one of the most important sources of heavy metals in the environment. Heavy metals can be dispersion on a large scale by binding to dust particles. This study aimed to evaluate and measure the pollution of heavy metals in subsidence dust of Sajzi plain in Isfahan.That now is the most important source of dust in Isfahan city.

After collecting samples for three seasons, this study determined the amount of lead, zinc, and cadmium, and then pollution indicators were assessed, such as accumulation index and contamination degree, etc

The contamination degree showed that cadmium and lead were in a very low degree of contamination and zinc was in a low degree of contamination. Also, the ecological risk index was a low-risk range for cadmium, lead, and copper. The environmental risk for the three elements was less than 150, which showed low-risk potential.

According to the distribution of pollution, it can be concluded that the pollution slope for the zinc and lead element was from northeast to southwest. The distribution of contaminated cadmium was different in three seasons. Stations 2 and 4 had the highest average pollution for the zinc element. Also, station 4 for the lead element showed the highest average pollution

Since use of domestic wastewater contain organic pollutants for irrigation of agricultural farms will lead to be adverse health effects, this study was conducted to compare the efficiency of brick kiln ash, thermal power plant ash and also commercial activated carbon for removal of chemical oxygen demand (COD) from domestic wastewater.

In order to removal of COD from domestic wastewater by studied adsorbents, under optimal conditions the effects of pH, amount of adsorbent, contact time and  agitation speed were evaluated. Also, equilibrium data were fitted to Langmuir (L) and Freundlich (F) isotherm models.

The results showed that the removal efficiency was increased by increasing in adsorbent dose, contact time and agitation speed. The optimum pH for COD removal was 7. Also, the results indicated that, the adsorption isotherm was well fitted by the Langmuir model with R2 = 0.997, 0.996 and 0.993 for commercial activated carbon, thermal power plant ash and brick kiln ash, respectively. Moreover, maximum adsorption capacity of COD for commercial activated carbon, thermal power plant ash and brick kiln ash were obtained 83.0, 28.6 and 14.9 mg/g, respectively.

Based on the results obtained, the commercial activated carbon found to be as an effective adsorbent for removal of COD from domestic wastewater compared to thermal power plant ash and brick kiln ash, but due to low cost of them, thermal power plant ash and also brick kiln ash could be used for removal of COD from wastewater.

Nowadays, increases in the extent of impervious surfaces in urban areas causes contributed to flooding and runoff contamination. Therefore, this study was conducted to assess Fe, Pb and Cd concentrations in surface runoff samples collected from regions with high traffic intensity in city of Malayer, west of Iran.

In the current study, a total of 15 surface runoff samples were collected from five selected stations. The samples were filtered (0.45 μm), stored in polyethylene bottles and were acidified at a pH lower than 2 by adding concentrated HNO3 in order to avoid metal adsorption onto the inner bottle walls. Element (Fe, Pb and Cd) concentrations were determined using ICP-OES (710-ES, Varian). All statistical analyses were done using SPSS version 20.0

The results showed that the mean concentrations of Fe, Pb and Cd in runoff samples were 0.220, 0.320 and 0.150 µg/l, respectively. Comparing the mean concentrations of analyzed elements with maximum permissible concentration (MPC) established by WHO and Iran DOE indicated that the mean concentrations of Pb and Cd were found to be higher than WHO permissible limits. On the other hand, the mean concentration of Cd was higher than Iran DOE permissible limits.

The results indicated that surface runoff from regions with high traffic intensity in city of Malayer were polluted with Pb and Cd, which could be threaten the surface water resources and health of citizens. Therefore, periodic monitoring and consequently treatment of runoff from rainfall before entering to surface water resources is recommended.