نشریه مهندسی بهداشت محیط
سال هشتم شماره 4 (پیاپی 33، تابستان 1400)

Spread prevention actions (SPAs) during Coronavirus pandemic period, such as increased hand-washing, temporary lock-downs, preventions in transportation, and the reduction of recreational and industrial activities may change the routines in social behaviors. Accordingly, SPAs can be effective on the quality and quantity of raw municipal wastewater. This research evaluates the aforementioned hypothesis and recommends solutions for the proper operation of wastewater treatment plants (WWTPs). 

For this purpose, the quantity and quality of sewage in 23 municipal WWTPs in Isfahan province, as the study area, were surveyed and compared from 2015 to 2020. SPSS software (version 23) was used for statistical analysis.

Results indicated that the annual growth rate of sewage discharged in the spring and summer of 2020 (period of SPAs) in the study area is 24% more than the average of annual growth rate in long-term (2015-2019). This increase is 45% in small WWTPs, while it is only 5% in large WWTPs. Results also revealed that the concentration of chemical oxidation demand (COD) of sewage was reduced 24% on average in this period. In addition, the biodegradability of wastewater is increased in large WWTPs mainly due to the decrease of industrial activities.

Therefore, SPAs in the pandemic period of Coronavirus could increase the quantity of municipal wastewater and reduce its COD concentrations. These variations may provide more appropriate operational conditions for waste stabilization ponds rather than activated sludge units.

Increasing use of pesticides along with an inadequate discharging of agricultural effluents has polluted water resources and severely affected the environment. 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the herbicides which is widely used all over the world. The aim of this study was to evaluate the efficiency of an electro-photo catalytic process for the removal of the 2,4-D from aqueous media. In this regard, Zn-doped Ni anode was stabilized on FTO surface by sputtering method.

In the present study, the effects of different variables on the efficiency of the electro-photo catalytic process such as pH (3, 5, 7, 9, and 11), electricity current (1-2 mA/cm2), electrode surface area (16-32 cm2), initial concentration of 2,4-D (10-50 mg/L) and retention time (0-90 min) were investigated in a batch model and on a laboratory scale. Besides, mineralization and kinetics of the process under the optimal conditions were studied. The residual concentration of 2,4-D was measured by HPLC at 283 nm.

The results showed that the highest removal efficiency of 2,4-D was obtained under the following conditions: pH=7, electricity current=2 mA/cm2, electrode surface area=32 cm2, initial concentration=10 mg/L and retention time=90 min. Under the optimal conditions, the maximum removal efficiency (i.e., 100%) and TOC of 79.5% were achieved. In addition, the kinetic studies revealed that the current process followed the first-kinetic-order model.

According to the obtained results, the applied electro-photo catalytic process can be considered as a suitable method for the removal of 2,4-D in aqueous solutions.

Air pollution is one of the most important environmental problems. Asphalt plants are the sources of air pollutants, especially particulate matters. The purpose of this study is to investigate the emission rate of PM2.5 and PM10 emitted from asphalt plants in the southwest of city of Tehran, also the present study was conducted to estimate the dispersion of particulate matters concentrations on surranding areas of a mining complex and city of Tehran.

This descriptive-cross sectional study was performed on the asphalt plants in a mining complex in the southwest of Tehran. In this study, at first the concentrations of PM2.5 and PM10 emitted from asphalt plants located in the southwest of Tehran were calculated using emission factors suggested by the US Environmental Protection Agency. Then, the dispersion of particulate matters concentrations was estimated on the surrounding areas of the mining complex with a radius of 50 km using the AERMOD model for the average times of 24 hours and annually using emission rate, meteorology and topography data. At last, the simulated concentrations were compared to EPA and WHO standards.

The maximum particulate matter concentrations are in the mining complex, and is gradually reduced by moving away from it. Dispersion of particles in the directions of dominant winds has been uniform. The maximum PM2.5 and PM10 concentrations have been estimated about 1 µg/m3 and 2 µg/m3 in Qods, 1 µg/m3 and 2 µg/m3 in Shahriyar, 0.6 µg/m3 and 1 µg/m3 in Andisheh and 0.2 µg/m3 and 0.4 µg/m3 in Tehran respectively in a 24-hour period. The amount of PMs that reached the west of Tehran continues to the eastern regions of the city. PMs concentrations were not significant in the average annual period.

Although dust emission rate from asphalt plants in the southwest of Tehran is acceptable, but it affects on the air quality in the surrounding areas of the mining complex and to some extent in Tehran. The cumulative effects of different industries can increase the potential health risks in the communities vicinity of this mining complex.

Surface and groundwater are important vital resources around the world. This study examines the quality of surface and groundwater resources in the catchment area of Latian Dam during the years 1396 to 1398 using GIS tools and water quality indices.
materials and ways  In order to evaluate the quality of water resources, samples were taken from 10 selected stations in two rainy and low rainfall seasons during three years and the physical, chemical and microbial parameters of the samples were evaluated. Then, using water quality indicators and hydrogeochemical characteristics, the quality of water resources was determined and the zoning map of the indicators was prepared using ArcGIS software. The resulting hydrogeochemical data were also interpreted using Piper, Schuler, Wilcox graphical diagrams and statistical analysis.

The results show that on average, during the rainy seasons, the whole region had good quality (30.644). For surface water stations, 3 stations in high rainfall season were of excellent quality (44.243), 2 stations in low rainy season were of excellent quality (40.145) and other stations were of good quality (69.92). According to the piper diagram, the samples are in two states Ca-Mg-SO4-Cl and Ca-Mg-HCO3 and the results of the study of cation and anion combination are mainly Ca-Mg-HCO3. Correlation coefficient between the main variables, there was a significant relationship between IRWQIGC groundwater and its GWQI (r = 0.87) and between IRWQISC surface water and its WQI (r = 0.68) but there is no significant relationship between groundwater and surface water quality. The average groundwater quality during the study period was good (29.143).

Anzali Wetland is one of the most important international wetlands located on the southern shore of the Caspian Sea. This wetland is habitat to valuable fish, aquatic animals and birds that are of ecological and economic importance. As a result of the increasing industrialization of wetlands, concerns about the impact of human activities on the survival of these valuable ecosystems are increasing. As a result of this study, the aim is to measure the pollution of some heavy metals in the water of the wetland and to estimate the potential risk of metals on the life of the wetland.

Water samples were collected from three parts of east, west and center of the wetland. The collected samples were poured into polyethylene containers, then pH of the samples was lowered below 2 with nitric acid and transferred to the laboratory and kept at 4 ° C until the final tests. To analyze the samples, an atomic absorption spectroscopy device equipped with a graphic furnace made by GBC Company from Australia, Sens AA model was used. Statistical analysis was performed using SPSS 19 software

The results indicate that the highest concentration of all studied metals was observed in the eastern part of the wetland. The mean concentrations of heavy metals in the wetland water were 4.943 for cadmium, 9.924 for lead, 82.4 μg / L for mercury and 0.115 for zinc and 0.03 mg / l for copper in the eastern part of the wetland, respectively. . In this study, the order of concentrations of the studied metals in water samples in all three regions was reported as Cu> Pb> Cd> Hg> Zn. Comparison between the concentrations of lead, cadmium, copper and zinc metals studied with world health standards (WHO) showed that these values were lower than the standard level while the concentration of mercury in the water of this wetland was 99% (P <0.001). ) Was higher than the standard. Also, the concentration of all studied elements in the water of Anzali wetland is in the range of no potential danger or low potential danger in both acute and chronic conditions.

The report of high concentration of metals in the eastern part indicates that the most pollution is in the eastern part of the wetland and this area is affected by various human activities. Also, the comparison of the present results with the previous results indicates an increasing trend, and unless special measures are taken by the relevant organizations, we will see the destruction of this valuable wetland in the not too distant future.

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely used in various treatments including inflammatory disorders, pain relief and fever. The permanent presence of these compounds in water resources and possible adverse effects due to toxicological and chemical properties is very important. The aim of this study was to evaluate of the efficiency of P4VP-Fe3O4 nanocomposite on the removal of diclofenac from aqueous solutions.

Adsorbent properties were determined by TEM, SEM, VSM and FTIR techniques. Effect of independent variables such as pH (3-9), adsorbent dose (0.1-2 g/L), contaminant concentration (2-20 mg/L), mixing speed (100-250 rpm), temperature (25-40°C) and the presence of interfering ions (120 min) were investigated. The adsorption process was evaluated using Langmuir, Freundlich, Tamkin isotherm models, and kinetic models of the adsorption process as well as thermodynamic studies.

Results showed that by examining the size and shape of P4VP-Fe3O4 composite, the composite had properties such as nano range size, polygonal structure and non-uniform shape. The peak of the pyridine ring in the results of FT-IR analysis of P4VP@Fe3O4 composite indicated the presence of C=C bands. In the adsorption process, the optimal removal conditions for diclofenac (contaminant concentration 15 mg/L, pH=5, contact time 75 min, adsorbent dose 1 g/L), the maximum removal efficiency of diclofenac 93.34% and adsorption capacity (qe) 9.33 mg/g was obtained. Also, the study of adsorption isotherm and kinetics showed that diclofenac adsorption followed Freundlich isotherm (R2 <0.956) and quasi-quadratic kinetic model (R2 <0.976). The results of thermodynamics also showed a spontaneous reaction.

P4VP-Fe3O4 composite can be used as an effective and useful adsorbent in the adsorption of diclofenac and pharmaceutical compounds from aqueous media due to its advantages such as simple and fast separation, recyclable, cost-effective and high removal efficiency.

Pre-ozonation in water treatment is used for various purposes such as; improving the coagulation process, reducing the production of trihalomethanes, color removal, removal of iron and manganese, control of microorganisms, and removal of organic matter. The main objective of this paper is to investigate the effects of pre-ozonation on the physical, chemical, and biological properties of drinking water.

This study on a real scale was conducted on the pre-ozonation unit of the Koohsabz drinking water treatment plant for 6 months. In this study, sampling of raw water entering the pre-ozonation unit and ozonized water was done randomly with glass sampling containers. 4 samples per month and a total of 24 samples were taken to evaluate the trends of changes in the parameters. The necessary tests according to the method presented in the standard method book (twentieth edition) on the samples have been done to investigate the effects of pre-ozonation on the physicochemical and biological parameters.

The studies showed that the turbidity and TOC (Total Organic Carbon) removal efficiency in the pre-ozonation process of the Koohsabz drinking water treatment plant was about 62% and 18. 83%, respectively, and it has no effect on pH. Also, the removal rate of Fe and Mn in the pre-ozonation process was 91.5 and 82%, respectively. Evaluate the effectiveness of pre-ozonation in watercolor removal showed that, by increasing the dosage and the concentration of ozone injection, significant changes did not occur on further reduction of color and color precursors and the removal rate of color precursor compounds, such as the chlorophyll a, is about 21%.

The results indicated that ozone could not change any physical parameters such as pH and color, but it has a significant effect on the chemical properties and reduced biological parameters by about 21%.

With the increase in recent droughts and shortage of drinking water resources led to planning to desalinate water and set up mobile stations. The purpose of this study is to determine the microbial and physicochemical quality of water discharged from desalination plants and tankers in Qom.

This descriptive cross-sectional study was conducted for one year with monthly sampling of water from domestic water purifiers and mobile tankers. Samples were analyzed for microbial contamination and physicochemical quality (pH, TDS, turbidity and chlorination) according to standard methods. The data were analyzed using SPSS and Excel software and compared with the standards.

Positive values of fecal coliform contamination was 13.34% in tankers and 4.35% in domestic water purifiers. The pH, TDS, turbidity was in accordance with the national and WHO standards. T-TEST statistical analysis showed, microbial quality of water had a significant relation with variables of dewatering containers (P<0.021), tank washing (P<0.001), outlet valve contamination (P<0.011), contact with dust (P<0.014), the personal health of the distributor (P<0.026), temperature (P<0.033), water retention time (P<0.019) and environmental sanitation (P<0.003). ). . But there was no significant difference in the distribution of water between tankers and desalination plants (P < 0.068).

By preventing secondary pollution, the water quality of these places can be considered desirable. Therefore, periodic and regular water evaluation and training on maintenance and health issues should always be considered