Environmental Health Engineering and Management Journal
Volume:2 Issue: 3, Summer 2015

Environmental contamination by chromium (Cr) has become an important issue due to its adverse effects on human health and environment. This study was done to evaluate the application of modified bentonite using sulfuric acid as an adsorbent in the removal of hexavalent Cr from aqueous solution. Adsorbent features were determined using x-ray diffraction (XRD), fourier transformed infrared spectroscopy (FTIR) and scanning electron microscope (SEM) techniques. Thereafter, the effect of pH, contact time, adsorbent dosage and different concentrations of Cr was investigated. The experimental data was fitness in terms of kinetic and equilibrium adsorption processes. The maximum capacity (Qm) of Cr(VI) according to Langmuir model was obtained at 4.21 mg/g. The experimental data properly obeyed the Longmuir and pseudo-second-order models. The highest percentage of Cr(VI) adsorption was observed at pH = 3 and the process after 60 minutes reached the equilibrium state. In Langmuir expression, the dimensionless constant separation term (RL) values for the adsorption of Cr onto the modified bentonite was in the range of 0-1, indicating that the adsorption is a favorable process and the modified bentonite has good potential in removing hexavalent Cr using sulfuric acid.

This study assessed the removal of organic material and nutrients from full-scale subsurface flow (SSF) constructed wetlands (CWs) followed by anaerobic stabilization ponds under environmental conditions. The effluents were distributed evenly in 12 reed beds. Samples were taken twice monthly for a total of 6 months from several points in the wetland. Biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS), and nutrient removal from the system and the longitudinal effect of the reed beds for removal of pollutions were determined. A full-scale model of flow, BOD, and nutrients in SSF in the CWs is presented. The flow rate and concentrations of parameters indicated that removal of organic matter and nutrients in the cold months decreased rather than in the hot months, as expected. The removal efficiency for BOD, COD, and TSS and the strongest biological interactions showed no uniform trends. The beds showed the highest removal rates in the first few meters of bed. The hybrid Monod-Plug flow regime and the Stover-Kincannon models showed the best fit for the kinetics of the processes. Umax in the Stover-Kincannon model was 3.64 mg/l.d for nitrogen and 0.24 mg/l.d for phosphorus. These values are very low, which indicates lower consumption and inefficiency of the system for removing nitrogen and phosphorus. It can be concluded that the SSF in CWs are able to treat average wastewater as effectively as common mechanical systems at lower cost.

Forecasting of air pollutants has become a popular topic of environmental research today. For this purpose, the artificial neural network (AAN) technique is widely used as a reliable method for forecasting air pollutants in urban areas. On the other hand, the evolutionary polynomial regression (EPR) model has recently been used as a forecasting tool in some environmental issues. In this research, we compared the ability of these models to forecast carbon monoxide (CO) concentrations in the urban area of Tabriz city. The dataset of CO concentrations measured at the fixed stations operated by the East Azerbaijan Environmental Office along with meteorological data obtained from the East Azerbaijan Meteorological Bureau from March 2007 to March 2013, were used as input for the ANN and EPR models. Based on the results, the performance of ANN is more reliable in comparison with EPR. Using the ANN model, the correlation coefficient values at all monitoring stations were calculated above 0.85. Conversely, the R2 values for these stations were obtained <0.41 using the EPR model. The EPR model could not overcome the nonlinearities of input data. However, the ANN model displayed more accurate results compared to the EPR. Hence, the ANN models are robust tools for predicting air pollutant concentrations.

Infections are readily transmitted as a result of bacterial contamination of swimming pools. Therefore, hygiene and preventing the contamination of swimming pools is of particular importance. The objective of this study was to determine the amount of bacterial contamination in indoor pools of Yazd in 2013. In this descriptive and analytical study, all indoor swimming pools of Yazd (12 pools) were evaluated during the spring and summer of 2013, in terms of bacterial contamination. In order to determine contamination, a sterile cotton swab was used for sampling. On average, 45 samples were taken from different surfaces in each pool (shower, dressing room, sauna sitting places, platforms and around the pool). In total, about 540 samples from all pools were tested for bacterial contamination. The results show that from 540 samples, bacterial contamination was observed in about 93 samples (17.22%); and was seen more in showers, edges of the pool and jacuzzis, and the slippers used in swimming pools. The most important isolated bacteria types were E. coli, Actinobacteria, Pseudomonas alcaligenes, Pseudomonas aeruginosa and Klebsiella pneumonia. The results indicate the presence of bacterial contamination on the surface of these places. It is recommended that health authorities pay more attention to cleaning and disinfecting surfaces around the pool, showers, dressing rooms etc, to prevent infectious disease transfer as a result of contact with contaminated swimming pool surfaces.

High concentration of salt makes biological treatment impossible due to bacterial plasmolysis. The present research studies the process of electrochemical oxidation efficiency and optimal levels as important factors affecting pH, salt concentration, reaction time and applied voltage. The sample included graphite electrodes with specifications of 2.5 cm diameter and 15 cm height using a reactor with an optimum capacity of 1 L. Sixty samples were obtained with the aid of the experiments carried out in triplicates for each factor at 5 different levels. The entire experiments were performed based on standard methods for water and waste water treatments. Analysis of variance carried out on effect of pH, salt concentration, reaction time and flow intensity in elimination of chemical oxygen demand (COD) showed that they are significant factors affecting this process and reduce COD with a coefficient interval of 95% and test power of 80%. Scheffe test showed that at optimal level, a reaction time of 1 hour, 10 g/L concentration, pH = 9 and 15 V electrical potential difference were obtained. Waste waters containing salt may contribute to the electro-oxidation process due to its cations and anions. Therefore, the process of electrochemical oxidation with graphite electrodes could be a proper strategy for the treatment of saline wastewater where biological treatment is not possible.

Traffic noise is one of the major sources of environmental pollution that can cause permanent or temporary loss of hearing in drivers. The purpose of this study was to estimate the prevalence of hearing loss among professional long-distance drivers in Bandar Abbas freight terminal. One thousand long distance occupational drivers in Bandar Abbas freight terminal not certified by underlying medical conditions were selected for this study. The demographic background, experience, type and kind of vehicles were recorded in a check list. Audiometry test was done at 500, 1000, 2000, 3000, 4000, 6000, and 8000 Hz using Welton 1300 audiometer equipped with AD-19 supra-aural earphones. Statistical analysis was done using analysis of variance (ANOVA). The age, experience, vehicle kind and weight of drivers were 34.02 ± 13.19, 8.21 ± 7.84, and 8.73 ± 6.12 years and 68.30 ± 15.61 kg. Approximately 52% of drivers studied had a degree of hearing loss. The most common type of hearing loss was sensorineural with mild loss of 69% and 70.9% for the left and right ears, respectively. Periodic medical examination with emphasis on the audiometry can be a way of diagnosing hearing loss in the drivers In addition to providing training courses for the drivers on hearing protection, the use of ear muffs equipment in the truck noise can also be considered as a solution.

This study quantified the effect of four popular culture media in a biodiesel production study on the qualitative and quantitative lipid content, dry biomass, and lipid productivity of Nannochloropsis oculata. Culture of microalgae was done separately in Walne, F/2, Sato, and TMRL media. In the logarithmic and stationary growth phases, biomass production and lipid accumulation of microalgae were measured and the constituents were identified by gas chromatography. N. oculata exhibited the highest rate of cell growth and biomass productivity of 0.2616 day-1 and 2.652 gl-1 in the Walne medium. The highest level of biomass conversion into lipids in TMRL medium revealed a cell dry weight of 37.22%. Walne medium proved to have the most efficient lipid productivity which was 0.1057 gl-1 day-1. The highest amount of triacylglycerol (TAG) was obtained in Sato medium in the stationary growth phase and was 75.25% of the fatty acids. The present study provides a practical benchmark, which allows the introduction of Walne as a suitable culture medium for N. oculata in biodiesel studies.

Composting as a waste management technology is becoming more widespread. The purpose of this study was to assess the feasibility and to find the most effective composting process for the ratio of green waste, digested and dewatered sludge from Chonibieh wastewater treatment plant in the west region of Ahvaz. The composting time was 23 days and the evaluated parameters in this period of the study were organic carbon, total nitrogen, phosphorus, carbon to nitrogen ratio (C/N), moisture content and pH. The C/N ratio was maintained at 30 with weight:weight ratio of 1:1, 1:2, 1:3 (digested and dewatered sludge to green waste). It was observed that vessel R3 produced higher quality of compost with final total nitrogen (1.28%), final total phosphorus (0.71%), final total organic carbon (TOC) (25.78%) and C/N (20.65%) within the 23 days of composting. While vessel R1 produced higher final total nitrogen and total phosphorus with lower amount of total coliform indicating suitable quality of composting. Therefore, the results showed that the characteristics of dewatered sludge mixed with green waste proportion of green waste significantly influenced the compost quality and process dynamics. The results also showed that the quality of final products in all the conditions was in agreement with Global Organic Textile Standard (GOTS) and World Health Organization (WHO) guidelines. However, the moisture content ratios were lower than the mentioned guidelines. With regards to microbial quality, all three ratios were in agreement with US Environmental Protection Agency (EPA) and Iranian guidelines. It is suggested that the final product of composting can be safely used in farmland and green space.