نشریه مهندسی بهداشت محیط
سال هفتم شماره 2 (پیاپی 27، زمستان 1398)

Recent industrial developments have led to the rapid development of electricity production successively; it leads to power grids and high voltage utilization. The effects of electromagnetic fields have been investigated on the organism by researchers. In many cases, it is not possible to conclusively comment, because of the slowness impact of fields of life-cycle processes and the long-term studies. According to the harmful effects of exposure to electromagnetic waves, this study was conducted to investigate the electric field intensity and magnetic field at high voltage substations (230 kv) in Golestan province.

This Cross-sectional study (descriptive-analytical) was performed at 230 kv substations in Golestan Province (1396). The electric field and the magnetic field density were measured by instrument model TM-190 at 5 posts in Golestan province and compared with the standards.

100 % of the measured electric field intensity and magnetic field of the 230 kv substations in Golestan Province is less than the standard.

The magnitude of the electric and magnetic fields is in the occupational limits.

The discharge of pharmaceutical effluent containing antibiotics into water resources is a great of concern associated with environmental pollution. In addition, conventional treatment systems are not capable of eliminating these antibiotics which commonly used in dealing with treatment of humans. Furthermore, over-consuming of antibiotics over the past few decades has forced researchers to find new techniques in order to deal with this environmental issues of great concern. In the present work, TiO2 was employed as a catalyst in the non-homogenous catalytic ozonation process for removal of Ceftazide antibiotics from synthetic sewage.

This fundamental-practical study was conducted in a pilot scale. The magnetic TiO2 nano-sized particles were synthesized through a sol-gel method. The properties of magnetized titanium dioxide nanoparticles as catalyst were characterized using SEM, XRD and EDX. The effects of variables: pH, catalyst dose, reaction time, pollutant concentration on the performance of catalytic process were investigated. The residual concentration of Ceftazide was analyzed by a high performance liquid chromatography (HPLC).

The findings of present study indicated that the high removal efficiency of Ceftazide occurs in alkaline conditions and a direct relation was observed between removal efficiency and pH. The catalyst dose of 2 g/l was determined as optimum dosage and the Ceftazide removal efficiency was improved by decreasing the initial concentration as time proceeded. The results showed that the removal of Ceftazide by this catalytic process are fitted with the first-order model.

The results show that the catalytic ozonation process with magnetized titanium dioxide nanoparticles has high efficiency for removal of Ceftazide from aqueous media. The catalytic ozonation process can be considered as an effective way to remove Ceftazide antibiotics from aqueous environment.

In the recent years, the use of municipal wastewater for irrigation has attracted the consideration of arid countries. Despite the potential use of municipal wastewater in plants irrigation as sustainable strategy, the environmental impacts need to be investigated. The aim of this study was to evaluate the use of treated wastewater in irrigation crop plants.

The present study was carried out to assess levels of iron, zinc, chrome, copper, manganese and nickel, in plants irrigated with water from different sources. Impact of different irrigation sources on metals uptake by plants were determined using Statistical tests.

According to the results, the type of water source (well water, treated wastewater) had a significant effect at 5% level on the mean concentration of Cu in barley leaves, Cr, Cu and Ni in barley root and Cu and Ni in soil around barley root. In this study, nickel concentration was higher than critical value in the soil around the roots for both plants and both irrigation sources due to the presence of nickel in the ultramafic rocks. Due to the proper performance of Birjand treatment plant stabilization ponds in reducing heavy metals from municipal wastewater, the concentration of most heavy metals in plant and soil in irrigation with treated wastewater was significantly lower than in irrigation with well water. The proximity of farms to heavy-duty vehicles increased the concentration of copper in all the situations studied which were close to the critical range. The concentration of chromium in shoots of plant was lower than other metals.

As a result, the values of heavy metals in different parts of plants were below the acceptable levels as suggested. In comparison to plants, the soil presented higher concentration of all studied metals. However, the regular monitoring of levels of these metals from well water and treated wastewater, in plants and soil is essential to prevent excessive build-up of these metals in the food chain.

Magnesium oxide is one of the alkaline earth metal oxides which due to its catalytic properties has been widely used in the analysis of hazardous chemicals. The main purpose of this study was to remove tetracycline antibiotics using magnesium nano oxide.

In this study, magnesium oxide nanoparticles were synthesized in the presence of cetyl trimethyl ammonium bromide. Synthesized nanoparticles were analyzed by X-ray diffraction (XRD), thermal analysis (TGA), transmission microscopic analysis (TEM), particle size distribution analysis (DLS), infrared radiation analysis (FTIR) and electron diffraction (FES) electron microscopy (FES). In the next step, the efficiency of the synthesized nanoparticles in the batch system was investigated by changing one parameter and keeping the other parameters constant in removal of the tetracycline antibiotic.

Increasing the pH from 3 to 7 caused efficiency increase, but decreased again to pH = 11. As the contact time increases, the efficiency increases. This increase was steepest for 60 minutes and is almost constant after 60 minutes. According to other available concentrations,the contact time of  60 minutes was chosen as the optimum time. The efficiency without the presence of interfering ions in optimum condition was 81.68%. By adding the interfering ions the efficiency at the lowest concentration level of the interferers was 62.29% (nitrate), 40.11% (sulfate), 55.32% (Cu) and 43.56% (fluoride) decreased. The highest reduction was obtained with sulfate ion at 300 ppm which showed an efficiency of 15%.

The results of this study showed that MgO adsorbent can efficiently remove tetracycline contaminants from water resources.

Today, the issue of urban solid waste or urban waste is one of the most serious problems in the whole world. Composting plants have a significant amount of time from the production and production stage to the sale and consumption stage. In this study, the effect of compost age on the quality of the compost factory was carried out in Isfahan City waste management organization.

To conduct this study, a compost mass of about 300 tons of newly produced compost and prepared for sale at a particular site from the plant and was done in a special place of four and nine weeks. There are ammonia, nitrate, ammonium, phosphorus, potassium, total nitrogen, mineral nitrogen, organic nitrogen, sodium, calcium, magnesium, carbon, density, EC, pH, oxygen, sulfur, and the ratio of carbon to nitrogen was done at any time with three iterations of the experiment.

Findings indicate that ammonia, nitrate, ammonium, total nitrogen, mineral nitrogen, EC, pH, moisture, density, and the ration of carbon to nitrogen in the initial compost are respectively as follows: 1800, 58.35, 28.2314, 14000, 2400, 11600, 145.7, 245.7, 85.6, 286, and 54.12. Finally in the 9th week, they changed as follows: 145.873, 325.81, 61.1122, 63.15065, 63.1215, 13850, 71.5, 35.7, 005.5, 5.279 and 04.22. The amount of ammonia, ammonium phosphor, mineral nitrogen, EC, moisture and density was reduced with a significant difference whereas other factors increased with a significant difference. The results of phosphor were not significantly different. Also, the results of the study revealed that ammonia, ammonium, phosphorus, total nitrogen, nitrogen, EC and COD in the zero weeks were respectively as follows: 244.26, 314.05, 298.73, 1153.6, 325.36, 6289.2, 37.088 and 3635.24, whereas in the ninth week, they changed as follows: 110.36, 141.89, 285.43, 366, 148.98, 217, 728.15, 5733.76. The amount of ammonia, nitrate, ammonium, total nitrogen, mineral nitrogen, organic nitrogen, as well as EC reduced with a significant difference, but the amount of COD increased with a significant difference. The results of phosphor and nitrate were not significantly different. 

Ultimately it can be concluded that the quality of compost is decreased with time lapse and the more it passes after the compost production, the less the food elements in the compost consumed by vegetarians would be.

Street dust is an environmental medium with complex composition in urban environment. Heavy metals remain in urban dust for a long time and re-suspended in the atmosphere. This study aimed to evaluate the metal richness and degree of contamination in Tehran street dust. 

Dust samples were collected from nine locations in Tehran in 2018. Heavy metals (Cd, Cr, Pb, Zn, Fe, and Al) were analyzed in street dust using ICP-MS. Metal richness and degree of contamination were determined using Enrichment Factor (EF), Geoaccumulation Index (Igeo), degree of Contamination (Cd) and modified degree of contamination (mCd). Pearson correlation (PC) and Hierarchical cluster analysis (HCA) were also used for analysis.

The mean concentration trend of elements was as Al (53486.54)> Fe (46535.07)> Zn (638.14)> Pb (200.33)> Cr (111.94), Cd (0.49) mg/kg. The highest metal enrichment was due to Pb and Zn. The geoaccumulation index also showed that Cd and Pb had the highest values. Degree of contamination indices also showed high levels of contamination in street dust. Significant correlation was observed between Zn-Cr-Pb and Pb-Cd. Significant negative correlation was also observed between relative humidity-Pb-Zn. Elemental clustering also showed that Pb, Zn, Cr, and Cd had anthropogenic sources and Fe and Al had natural sources of diffusion.    

The results of this study showed that the street dust of Tehran is highly polluted. Therefore, this environmental medium can have significant negative effects. Therefore, continuous monitoring of street dust is essential.

One of the most important problems facing the water treatment plants is seasonal turbidity removal from the drinking surface waters. In this work, the efficiency of turbidity removal from water surface has been studied using a batch rotary reactor model and electrocoagulation process and different electrodes including iron and aluminum were tested. Finally, the optimum values of the studied parameters were evaluated at different operating conditions.

In order to eliminate the turbidity from drinking water, the discontinuous rotary reactor model with monopolar electrodes was used in parallel connection. The sample volume in the experiments was 377 liters, and the rotation of the model caused all fluid particles, sediments, and contaminants to be homogeneously touched with the electrodes. This model provided a higher efficiency of turbidity removal due to not having pump blades and return pipes.

Results of this study showed that the maximum efficiency of turbidity removal from drinking water would be achieved by using the material of aluminum for electrode and considering time duration of 60 min,  rotation speed of the model equal to 1.3 rpm, current density of 18.8 A/m2 in pH=7.4 and electrode gap distance of 3 cm. At these conditions the maximum turbidity removal efficiency was obtained 84.1 and 93.3% for the iron and aluminum electrodes, respectively.

Results of this work showed that the proposed batch rotary reactor model, in addition to its easy application, is able to remove turbidity from the aqueous solutions at a the high efficiency. Therefore this model would be strongly suggested for application in drinking water treatment plants.

The Physical, chemical and biological parameters one of the most important factors determining the quality of drinking water. The overall purpose of this project is to investigate how the quality of water entering the plant in changing the water-color and creating the foams in different units of water purification. 

 This study is a case study and in real scale on the raw water inlet to the Koohsabz drinking water treatment plant has been done. The study was conducted over a period of 6 months (February 2016 to July 2017). In the first stage, the raw water quality was assessed according to standard methods. In the second step, the effect of each of the parameters on the color and foam formation in the water treatment process units and the mechanism of effects have been examined.

Average changes in temperature, turbidity, the color of the water entering the plant during the study period were 15.8oC, 6NTU, and 6TCU respectively and pH ranges from 6.9 to 8.4. Mean change of EC, TOC and DOC respectively is; 765 μS / cm, 5.8mg /l and 3.53mg /l. The average change UV254 and SUVA were 0.178 l / m and 5.856 L/ mg, respectively. Also, the mean changes of humic acid, surfactant, and chlorophyll a in the input raw water were 0.24, 0.05 mg / l and 2.4 μg/m2, respectively.

Investigations showed that the water quality parameters of water entering the treatment plant are effective in creating color and foam in water treatment process units.