نشریه مهندسی بهداشت محیط
سال ششم شماره 4 (پیاپی 24، تابستان 1398)

Dyes are resistant organic matter because they have an aromatic rings. Sulfate radical (SO4●-) is a powerful oxidative radical. The design via CCD, cause the process was done by high accurate and low-cost. The aim of this study was modeling of UV-EPS process to degradation of Acid Blue 25 dye via the CCD from aqueous.

In this experiment study, used to a photoelectrochemical reactor with two iron electrodes as an anode and two titanium electrodes as a cathode and Low-pressure mercury lamp (254 nm). The pH (2-4), Direct Current (0.75-1/5 A), S2O82- concentration (0/5-1/5 mg/l), reaction time (20-40 min) and initial concentration of AB25 (50 -100 mg/l) as a main independed variables were chosen. Also, COD, synergist effect, presence of radical scavenger and kinetic of reaction were studied in optimum conditions. Dye concentration and COD were measured by spectrophotometer (DR5000).

The results illustrate that the efficiency of process is affected by the variables. Optimum condition obtained in pH=3/01, DC was 1/08 A, PS was 1/30 mg/l, reaction time was 34 minute and initial concentration equal to 50 mg/l. In this situation efficiency of process was 91 percent. The COD removal in these conditions was 69 percent. The correlation coefficient was 0.84 which indicates that the quadratic model is suitable for process design. The kinetics of reaction followed the first order kinetics. Reduce of efficiency of process in the presence of radical scavenger occur.

Optimizing via CCD reduces the number of runs and increases accuracy. This process has a high efficiency in dye and COD removal and this process can be used to reduce the pollutant loading form industrial wastewater, such as textile wastewater, before discharging into the environment.

Antibiotics are considered due to health and environmental problems and therefore they counted as a major threat to human health. The aim of this study was to determine the absorption efficiency of magnetic-chitosan nanocomposite in the removal of antibiotic tetracycline from aqueous solutions.

In this study, the experiments were performed by spectrophotometer. The magnetic-chitosan nanocomposite were considered as an antibiotic adsorbent which its adsorption efficiency was measured by changing the variables such as temperature, time, PH, dosage of magnetic-chitosan nanocomposite, concentration of tetracycline, concentration of interactive ions of chlorine, sulfate and carbonate. Synthesis of magnetic-chitosan nanocomposite was based on co-precipitation method. The Freundlich, Langmuir and Temkin isotherms were used to determine the isotherm and the absorption kinetics.

The results showed that the best antibiotic removal efficiency was obtained at pH = 6. The highest removal efficiency was obtained at 90 minutes and equal to 91.23%. Moreover, the removal efficiency of tetracycline was significantly reduced in alkaline pH. Also, by increasing the absorbent dose from 0.1 g/L to 0.5 g/L, the removal efficiency of the pollutant increased from 72.24% to 90.22% at 90 minutes. In addition, with an increase in pollutant concentration between 5-30 mg/L, the removal efficiency of the pollutant decreased from 93.4% to 53.7%. In order to study the thermodynamics of the tetracycline pollutant absorption process by magnetic-chitosan nanocomposite, the removal efficiency of the pollutant dropped from 91.23% to 45.1% at 20, 30 and 45 degrees of Celsius. The presence of interfering ions has a decreasing effect on the removal efficiency of tetracycline, which the removal efficiency were reduced from 91.23% at 90 minutes (in the absence of ions) to 70.16% (for chlorine ion), 65.96% (for ion Carbonate) and 54.2% (for sulfate ions).
               

Finally, the use of magnetic- chitosan nanocomposite adsorbent is recommended in the removal of antibiotic tetracycline.

Cr (VI) is a highly toxic and carcinogenic contaminant and that are used in the steel industry and other chemical industries such as the leather industry, pigment production, electroplating of metals and the production of anticorrosive compounds. Its waste enters the environment and subsequently enters the water and food sources. Therefore, in order to protect the environment as well as human health, it is necessary to remove this pollutant from the environment, including soil, using appropriate methods.

Chromium resistant bacteria were isolated from the chromium contaminated soil and adapted by serial culture in Cr (VI) concentrations of 50-400 mg/L and microorganism growth and Cr (VI) reduction were measured. Then the soil was artificially contaminated at the laboratory by Cr (VI) compound (CrO3) and Organic compounds were added to soil at the Specified amount. Finally, a separated bacterial mix was added to the soil to initiate the bioaugmentation process.

After 3 stages of sampling and data analysis, the results of the study showed that Cr (VI) reduction efficiency by the bacterial mix reduced decrease by Cr (VI) concentration increase. So, under similar conditions, the efficiency of Cr (VI) reduction of soil, at a concentration of 50 , 200 and 350 mg / l, is about 86%, 51% ,and 26% respectively .Organic compound adding also increase bioaugmentation efficiency.

The results of this study showed that optimizing soil conditions could improve the biodegradation process, especially in low concentrations of contaminants.

Unsustainable development of agriculture and aquaculture has reduced the water quality of rivers. The most important aim of this study is assessing of water quality in the Ghezel Özan basin in Zanjan province.

18 sites were selected based on standard criteria including land use, geology, biodiversity points, accessibility and standard distributions. Content of Dissolved Oxygen, Temperature, Turbidity and Electrical Conductivity were measured in-situ while number of Fecal Coliform, amount of BOD, COD, Phosphate, Nitrate, Nitrite, Ammonia, Sulfate and Chlorine were measured at laboratory.

One-sample T.test showed a significant difference between the Coliform and its standard. Results have illustrated the remarkable impacts of agricultural and aquaculture activities on the river health. Also, among all quality parameters, Nitrate and Fecal Coliform show a significant difference in two regions, Tarom and Mahneshan. There is the best water quality in site 7 (upstream site) located far from human access. IRWQI index (Iranian water quality index for surface water) shows the best results because of more overlap with land-uses and the trend of variables.

Olive cultivation and unsustainable aquaculture development in Tarom and Mahneshan, respectively, are main reasons for decreasing of water quality. So, integrated water resources management, training local people, assessing environmental impacts and determining the ecological potential are highly recommended to improve the water quality of the studied river.

Due to the large volume of water consumed in textile industry and producing the colored wastewater containing non-biodegradable organic dyes, in the present study the interaction of hydrogen peroxide and nanophotocatalyst in the advanced oxidation process was investigated.

In this research, after synthesizing of nanophotocatalyst (ZnO:Ag:Nd) the effect of hydrogen peroxide on dye removal process, and its interaction with the catalyst was investigated. photocatalyst was characterize by  (FESEM) Field-emission Scanning Electron (EDS) Energy-dispersive X-ray spectroscopy (XRD) X-ray diffraction methods. Then, the effect of important operating parameters such as dye concentration (10-30 ppm), pH (3-9), The amount of photocatalyst (0.02-0.1g.L-1) temperature (30-50°C), hydrogen peroxide concentration (F=2-11) was evaluated in AOPs process. Process modeling was done by using the response surface methodology.

The results showed that by adding hydrogen peroxide to photocatalyst particles, the efficiency of decolorization was increased, but the addition of catalyst to the optimum amount of hydrogen peroxide reduced the efficiency of decolorization. Also, the optimum conditions for the removal of dye matter (pH=6.21) and the amount of photocatalyst 0.08g.L-1, F=9was achieved. The results of the thermodynamic studies showed the endothermic reaction of the process, and process modeling indicated that the theoretical result were in accord with the experimental results.

Based on the results, combination of using catalysts and hydrogen peroxide is an effective technique for dye removal of aqueous solution.

Leachate from solid waste in uncontrolled landfills can have many effects on the environment and human health. The purpose of this study was to investigate the variation of physical and chemical properties of leachate from Isfahan Compost Plant Reception Hall during time.

In the present study, samples were collected from leachate of a compost plant in Isfahan for 12 months during the years in 2016 and 2017. Different physico-chemical properties including biochemical oxidation, chemical oxygenation, total soluble solids, total suspended solids, nitrate, total nitrogen, phosphorous, pH, EC, sodium, calcium and potassium, as well as concentration of 9 metallic elements of iron, lead, nickel, chromium, cadmium, magnesium, zinc, copper and manganese in the leachate were measured during the time.

Concentration of potassium, calcium, sodium, sulfate, nitrate, phosphorus, total nitrogen, TSS, TDS, COD, BOD in leachate samples was in the range of 2150-5216.04, 698-70000, 1530-4600, 1302-4547, 192-3944.30, 0-4149, 7-7900, 9614-87000, 8368-77850, 71200-116800, 47800-75000 mg/l, respectively. The pH and EC of the leachate varied in the range of 4.23-5.30 and 21.30-49.7 dS/M, respectively. In addition, the concentration of heavy metals of iron, lead, nickel, chromium, cadmium, magnesium, zinc, copper and manganese, ranged from 49-220, 0.57- 23, 0.5-0.25, 0.5-7.5, 0.1-0.94, 0.03-2.50, 566-1090, 12.50-39, 0.28-9 and 3.50-33 mg/l, respectively.

The amount of BOD5 and COD was higher in April and March, in which the average rainfall was higher than other months. Also, TDS in June, with zero rainfall, was higher compared to other months. Comparing the mean concentration of elements (except chromium), the physical and chemical parameters of the leachate with the effluent discharge standards of the Iranian Environmental Protection Agency indicated that the concentrations was several times higher than the standard limit. The results of leachate analysis showed that leachate from municipal waste from the compost station line of Isfahan had a high potential of environmental contamination, which should be controlled and monitored continuously.

Emission inventory of mobile sources is an essential element for studying the air quality. In order to support the development of public policies with an approach to reducing the overall mass emissions of air pollutants, the aim of the current study was preparation of a GIS based emission inventory of Karaj mobile sources air pollutants.

In the present study in 2016, the International vehicle emission model (IVE) was used to estimate the amount of emissions of CO2, CO, NOx, VOCs, SOx and PM and the GIS environment was used to show the distribution of pollutants emissions during the morning rush hours in Karaj pathways.

The results showed that the maximum amount of air pollutants released during morning rush hours was as CO2 (5944.07)> CO (297.55)> NOx (32.70)> VOCs (31.16)> PM (21.24)> SOx (1.102) Kg/h in Karaj. Heavy vehicles were responsible for maximum emission of CO2, NOx and PM and light vehicles were responsible for the release of CO, VOCs and SOx.

This inventory is useful for politicians and researchers to better understand the current conditions of air pollution in the region and will provide a vital input for air quality modeling and policy making.

Population growth and increased human activities in urban communities lead to large volumes of waste. This waste volume causes problems for human health and environmental pollution. Recently, a living environment assessment has been developed to improve the situation. The purpose of this study is to compare the environmental impacts of four urban waste disposal scenarios in Rasht city.

In this research, the amount of waste and the data required for logging were first determined and then the four life cycle assessment stages were performed in relation to each of the defined scenarios. Finally, the results were analyzed using the IWM1 model it placed.

The results of this study indicate that by disposing of some of the waste in the organic fertilizer plant by composting and landfilling, part of it in the district of sanitary and energy extraction and increasing the recovery rate, we can see a significant reduction in the emission of pollutants was environmental. The ecological index was the best scenario is -2.10E+6 And for the most devastating scenario +2.39E+07 was obtained.

According to the environmental assessment and comparison of the results of the life cycle logbook, the first scenario (collection; compost; recycling; landfill) with an ecological index plays an important role in reducing pollution and energy consumption and the title has been chosen as the top management option and has been made available to experts and decision-makers.