نشریه مهندسی بهداشت محیط
سال هفتم شماره 1 (پیاپی 25، پاییز 1398)

Gasoline fuel vehicles cause emissions of airborne pollutants that are poisonous and have a deleterious effect on human health and the environment while natural gas fuels have less harmful effects on the environment and humans due to their greater environmental compatibility. The propose of this study is to investigate the concentration of CO, HC, O2 in the exhaust outlet of gas and diesel cars that is referred to the technical examination center and to compare the distribution of these gases based on the fuel type of the vehicle and the lambda coefficient. 

This study was conducted on 1000 vehicles tested in technical examination centers in Shiraz city. To do this, the distribution of air pollutants including CO, H, O2 exhaust from Pride, Peugeot 405 and Samand, which were obtained with two types of gas and gasoline combustion and the relationship between the distribution of these gases with the lambda coefficient and the gasoline and gas type in these three types of vehicles was analyzed by t-test with a significant level (p <0.05).

The results showed that there is a significant relationship between vehicle fuel type and CO, HC and O2 emissions from car exhaust (p <0.05) and in gas-fueled cars, it was less gasoline-burned. Also, by increasing the lambda coefficient, the oxygen content of the exhaust was increased while the contaminants, HC, CO decreased. Therefore, with the desired performance of the combustion chamber and the optimum consumption of oxygen in the combustion process, fewer pollutants are produced and introduced into the air.

Also gas-fueled cars have higher lambda rates than gasoline cars and emit less pollution in the air.

Advanced Hybrid Oxidation Processes(AHOPs) have the ability to romove the pesticides. The aim of this study was optimization of sono-electroperoxone process (US-EP) in the removl of 2.4 D from aqueous via RSM.

The pilot that used to in this study included an ozone generator, an ultrasonic generator and an electric direct current source. Two graphene electrodes as  anodes and two titanium electrodes as cathodes were used. This electrodes connected to DC as direct monopolar connection. pH, direct electric current, ozone gas concentration, reaction time and initial 2,4 D concentration were optimized as  an independet and inffluence parameters. COD and TOC removal, kinetics of reaction, synergyist effects of variables, presence of radical scavangers and optimal electrolyte concentration were determined in optimum condition.

Efficiency of process was 55-90 percent in different runs. The optimized conditions are modeled was pH=6/04, ozone concentration equal to 2 mg/L.min, electric current equal to 1 amperes, 2, 4 D concentration equal to 30.3 mg/L and in 103 minutes reaction time in the presence of ultrasonic waves with frequencies 40 kHz. The Efficiency of US-EP in this situation was 95 percent. COD and TOC removal were 71% and 63%, respectively. The kinetics of the process follow the first order kinetics. The P-Value and F-value was determined by ANOVA analysis 0.0033 and 24.19 respectively, which indicates the model is significant. R2, R2 adj and R2 predicted were 0.94, 0.84 and 0.89, respectively.

US-EP process had a high performance in removing of 2.4 D. The process is an environmentally friendly process because don’t use of chemicals.

Water resource management in order to preserving and supplying of high-quality water, plays an important role on communities health. For this reason, humans have always used different methods to provide high-quality water. One of these methods is the use of Radial Collector wells. In this study, the effect of Radial Collector wells on the microbial and physicochemical quality of Doogh River during 5 years has been investigated.

In this study, we assessed some water quality parameters on Dough River (DR) and its adjacent Radial Collector Well (RCW) which supplies water shortage of Gonbad Kavous city, Golestan province, Iran. For this purpose, monthly samples during 2012 to 2016 were collected from DR and RCW, then parameters included nitrate, phosphate, turbidity, pH, fecal coliform, and temperature were measured. Finally, effect of time variation and infiltration of water from DR to RCW on qualitative parameters was analyzed.

According to the results, nitrate, phosphate, turbidity, pH, and fecal coliforms significantly decreased during infiltration process (P-Value <0.05). In addition, the time variation of nitrate, phosphate, turbidity, temperature, and fecal coliforms had significant difference.

The present dataset demonstrated that RCW has a good efficiency for reduction of measured parameters. Also, monthly variations can be effective on water quality of resources.

Microbial contamination is one of the main concerns about the use of treated wastewater in irrigation. Therefore, the present study conducted to investigate the effect of treated wastewater on microbial contamination of urban landscape soils in Zahedan.

In this study, a 1600 m2 plot of palm trees in Zahedan were irrigated with treated wastewater and one plot were irrigated with well water (control treatment) were selected. From the soil of two plot, a random sample of 16 samples from 0 to 50 cm depth were collected in 1397. Sampling were done from treated wastewater and well water. Physical, chemical and microbiological properties of treated wastewater and well water and microbial parameters of soil samples were measured according to standard methods. Data were analyzed using a randomized complete block design with MSTAT-C softwares.

Based on the results of analysis of variance, the application of treated wastewater has a significant effect on the microbial parameters of irrigated soils in a 1% statistical level. The results of comparison of meanings by LSD showed, the application treated wastewater at compared to well water significantly (p<0.05) were increased total coliforms, fecal coliforms and egg parasites of soils to 93.3%, 86.8% and 80% respectively. Also, the soil microbial parameters of palm trees were higher than that of the control treatment and the standard limit for agricultural land.

The chemical quality of Treated Wastewater of the Zahedan was consistent with the standards of the Iranian environmental organization in terms of its application in agriculture. However, number of the total coliforms, fecal coliforms and egg parasites of treated Wastewater, as well as in the surface soil of palm trees were irrigated with this wastewater was relatively high that could be accepted for limited irrigation according to the Global Health Guidelines.

Nowadays, soil pollution with total petroleum hydrocarbons (TPH) is one of the major environmental issues caused serious problems to human and other living organisms. One of the best and most reliable methods of bioremediation is the use of earthworms known as vermin-remediation. In this study, bioremediation of gasoline-contaminated soil using Eisenia Fetida, the mixture of activated sludge and compost was evaluated.

In order to determine the efficiency of bioremediation to removal gasoline from contaminated soil, cow compost and urban sewage sludge with a weight ratio of 1: 0.35:0.25, was used. Experiments were carried out in 6 reactors with different concentrations of diesel (10 and 30 g / kg soil), a different number of Eisenia Fetida earthworm (10 and 20) at ambient temperature during 90 days. To compare the performance of biodegradation of gasoline using Eisenia Fetida earthworm, two control reactors that contained only contaminated soil with two ratios of gasoline, vermicompost and activated sludge, were used. The (TPH) decomposition rate was measured by GC-FID. Results of this study were analyzed by Minitab version 17 software.

Results indicated reactor No.3 has the best removal efficiency of light hydrocarbons during 90 days. the removal efficiency of average hydrocarbons was  70% and heavy hydrocarbons with the highest removal efficiency of 68% in reactor No. 4 with characteristics Soil polluted with 10 g / kg of soil + 20 number of Eisenia Fetida, With a significant difference of other reactors.

Based on the results of this study, the degradability of hydrocarbons has increased significantly with the addition of organic modifying materials and the increase in the number of earthworms.

In this research, TiO2-Zr nano-photocatalyst was firstly developed with the aim of improving the photocatalytic activity of titanium dioxide via sol-gel method. The recovery of catalysts in acidic, alkaline and thermal conditions was also studied.

This research was done on a laboratory scale. The structures and properties were recognized with (BET), (FT-IR), (FE-SEM), and (XRD) methods and the band gap value of the synthesized nano photocatalyst found to 3 eV with DRS. Also, the effect of color concentration, soluble pH, catalyst powder concentration and contact time was kept constant in order to economically effect on the efficacy of dyeing. Then, photocatalytic activity was evaluated for degradation of organic pollution days Acid yellow 36 in aqueous solution specimen by the UV-Vis spectrophotometer and total organic carbon (TOC).

Finally, after obtaining the optimum conditions for degradation efficiency, it was compared with titanium dioxide photocatalyst, which revealed that increase in efficiency due to changes in the band gap and, as a final point, shows the power of photocatalytic activity of synthetic doped material in degradation organic environmental pollutants.

It founded that doping Zr ions to the TiO2 lattice causes decreasing band gap value, so As a result, the necessary energy to stimulate the electrons from the valence band reduced in results wavelength shift up. The photocatalytic activity has a significant impact on color reduction and has a high potential for the decolorization organic dye wastewater.

Because of the importance of the role of energy in the world and nonrenewability of fossil fuels and caused environmental issues by these fuels in recent years, many studies have been conducted to find an appropriate alternative to fossil fuels in different countries of the world. Biofuels such as (biodiesel and bioethanol) have been introduced as one of the most desirable alternatives.The purpose of this study is investigation the production of biodiesel from waste frying oils in the presence of a homogeneous catalyst.

This study is an experimental-laboratory. In this study, the impact of three parameters including reaction time (60,70 and 80 minutes), weight percent of catalyst (.5, 1 and 1.5 percent) and molar ratio of methanol to oil (3:1, 6:1 and 9:1) Was investigated at three levels. The biodiesel production efficiency was calculated using the produced biodiesel mass from the amount of consumed primary oil.

The maximum production efficiency of biodiesel in the presence of sodium hydroxide as homogeneous catalyst was obtained 86.6 ± 3.23%. Optimum conditions for the maximum efficiency were methanol to oil molar ratio of 6:1, weight percent of catalyst 1 and reaction time of 70 minutes. In this study the reaction temperature and mixing intensity were considered of 65 ° C and 500 rpm respectively.

The waste frying oils of restaurants that are producing a lot in our country are a great source for biodiesel production and energy supply.

Water interfering anions can cause major problems in the quality of drinking water as well as entering water to the industry. The purpose of this study was to determine the efficacy of granulated metallic-magnetic chitosan nanocomposite for adsorption of interfering anions in aqueous solutions (sulfate, chloride, carbonate and bicarbonate.

Synthesis of granulated metallic-magnetic chitosan nanocomposite was conducted based on co-precipitation method. The anions chloride (300-50 mg / L), carbonate (150-50 mg / L), bicarbonate (50- 150 mg / L) and sulfate (50-300 mg / L) were considered. The pH range of the study was between 5- 8 and the remaining time was 0-90 minutes. For the study of the adsorption process, the Langmuir and Freundlich isotherms were considered as pseudo-first and pseudo-second kinetics order at temperatures in the range of 20-45 Celsius.

The results showed that the best removal efficiency of anions was obtained at pH = 5. With an increase in chlorine concentration from 50 mg / L to 300 mg / L, the removal efficiency decreased from 80.06% to 38.22%. This trend has also been observed for other anions in the study, which decreased from 57.82% to 37.69% for sulfate at similar concentrations. In carbonate and bicarbonate, at 50-50 mg / L concentrations, the removal efficiency decreased from 61.15% to 41.17% and 79.66%, respectively, to 49.36%. The percentage of removal of chlorine ion with an amount of adsorbent between 1-5 g / L increased from 62% to 91%. However, increasing the amount of absorbent after 4 g / L did not have a significant difference in removal of chlorine. The same effect was observed for other anions in the study, so that the removal efficiency of carbonate, bicarbonate and sulfate anions in exchange for an increase in the absorbent dose increased from 1 g / L to g / L 5, which was 56% to 93%, 52% to 96% and 53% to 80%. The results of the study showed that the adsorption process follows Langmuir isotherm model and the adsorption of anions is superficial. The absorption model also follows the pseudo-second order kinetic model. In addition, as the temperature rises, the removal efficiency decreases.

The results of the study showed that granulated metallic-magnetic chitosan nanocomposite adsorbent was able to remove the interfering anions from water resources.