Defined as any substance in the air that may harm humans, animals, vegetation, and materials, air pollution poses a great danger to human health. It has turned into a worldwide problem as well as a huge environmental risk. Recent years have witnessed the increase of air pollution in many cities around the world. Similarly, it has become a big problem in Iran. Although ground-level monitoring can provide accurate PM2.5 measurements, it has limited spatial coverage and resolution. As a result, Satellite Remote Sensing (RS) has emerged as an approach to estimate ground-level ambient air pollution, making it possible to monitor atmospheric particulate matters continuously and have a spatial coverage of them. Recent studies show a high correlation between ground level PM2.5, estimated by RS on the one hand, and measurements, collected at regulatory monitoring sites on the other. As such, the present study addresses the relation between air pollution and satellite images. For so doing, it derives RS estimates, using satellite measurements from Landsat satellite images. Monitoring data is the daily concentration of PM2.5 contaminants, obtained from air pollution stations. The relation between the concentration of pollutants and the values of various bands of Landsat satellite images is examined through 19 regression models. Among them, the Ensembles Bagged Trees has the lowest Root-Mean-Square Error (RMSE), equal to 21.88. Results show that this model can be used to estimate PM2.5 contaminants, based on Landsat satellite images.

This study aimed to evaluate the concentration of heavy metals in liquid effluents and to quantify the mercury content in dental amalgam waste generated by dental clinics. Three neighbouring cities in Northeast Algeria were considered in this study (Constantine, Skikda, and Annaba). Heavy metals, such as Hg, Cu, Zn, Fe, Ni, Mn, Cr, Cd, and Pb, were analysed in wastewater and then compared with acceptable standard values. Special attention was given to mercurybecause of its dangerous effects. The results collected indicated the presence of heavy metal contamination in dental wastewater. Heavy metal concentrations were significantly high for all heavy metals and exceeded the allowed concentrations. However, Pb and Cr were shown to have acceptable concentrations. This study highlights the possible contamination of the environment by mercury and heavy metals generated by dental clinics. This study also demonstrates an order of magnitude of the concentration of these heavy metal in a large agglomeration with a population of 2.5 million people.

Air quality in greater Algiers, in Algeria was assessed analyzing aerosol particulate matter (PM10 and PM2.5) at a site influenced by heavy road traffic. Particulate matters were collected using a Gent sampler to characterize the atmospheric aerosol of Algiers. An Energy dispersive X ray spectrometer (EDXRF) was used to determine the heavy metal concentrations in the PM2.5 and PM10 size fractions. Principal Component analysis and Enrichment factor were used to identify the major sources of air pollutants for PM10 fraction in the studied area. Backward trajectories were calculated in order to identify potential distant sources that contribute to particulate pollution in our site. Significant concentrations of PM 2.5 and PM10 as well as associated heavy metals have been documented. The mean concentrations of heavy metals contained in PM10 and PM2.5 were, in descending order, Fe>Zn>Ni>Pb>Mn>Co>Cr; Pb>Mn>Co>Fe>Zn>Ni>Cr respectively. The contribution of road traffic to the levels of fine (PM2.5), and coarse (PM10) particles were studied.

Environmental pollution and strict emission norms are promoting researchers to explore the methods for reducing pollution and provide optimum solution. By considering these situation as the baseline, study was conducted to analyse the effect of exhaust gas recirculation (EGR) on performance and emission of the DI diesel engine. The effects of Injection Timings (IT), split injection and Exhaust Gas Recirculation on performance, emission characteristics of diesel engine fuelled neem biodiesel blends are investigated. Initially experiments are conducted with diesel, NB5, NB10 with original injection timing of 23° bTDC with direct injection and are considered as base reading. The fuel injection is optimized (at 19° bTDC and 16% split injection) and the effect of EGR rate at this optimized condition is analysed. Significant reduction of about 65.3%, 67% and 57% in the amount of NOx was obtained at full load as compared to base readings. Smoke emissions reduced by 2.8-3.4% and CO emissions reduced by around 52% for diesel and biodiesel blends at full load.

Air is one of the precious natural resources that are essential for animal including the human being. It is also the most important gift of nature without which human cannot survive. Pollution in the urban areas like Cairo, Delhi, Mexico and Dhaka far surpasses the acceptable limits set by the World Health Organization (WHO). Urban air pollution in the South Asian region is approximated to cause more than 300,000 deaths and billions of cases of respiratory disease per year. In Bangladesh, about 200000 people die each year due to the air pollution as the WHO estimates in 2018. The air in Dhaka City, the capital of Bangladesh, has become worsen to a level that the city has been identified as one of the most polluted cities in the world. Taking the problem with utmost importance into consideration as it is related with the public health, air pollution is being treated as one of the priority issues. The level of pollution at roadside environment is deeply connected with the density of motor vehicles plying on the roads. This situation is expected to worsen further in the upcoming days due to the increasing number of motor vehicles resulted from rapid economic growth and industrialization. This paper aims to provide the present statues of the air pollution in Dhaka city and some specific recommendations for making the city as a better living place through reducing its air pollution.

It has been more than 20 years that the Measurement of Pollution in The Troposphere (MOPITT) mission onboard the NASA Terra satellite keeps providing us CO atmospheric concentration measurements around the globe. The current paper observes CO mixing ratio from the MOPITT Version 8 (MOP03J_V008) instrument in order to study the spatiotemporal analysis of CO (spanning from April 2000 to February 2020) in the Troposphere of Iran. Results indicate that the average CO in Iran’s troposphere has been 133.5 ppbv (i.e., 5.5 ppbv lower than the global mean CO). The highest distribution of CO (with an average of 150 ppbv) belongs to the city of Tehran (the capital of Iran) as well as the Caspian Sea coastal area, while the lowest value (with an average of less than 110 ppbv) has been estimated on the Zagros Mountains (southwestern Iran). The highest and lowest CO values have been observed in cold and hot months, respectively. Seasonally speaking, it is also clear that the highest and lowest carbon monoxide values occur in winter and summer, respectively. The vertical profile of MOPITT CO shows the maximum CO concentration at lower levels of the troposphere. It has been expanded up to 150 hPa. The trend is investigated by means of Pearson correlation coefficient statistical method. Overall, long-term monitoring of MOPITT CO in Iran indicates a decreasing trend of tropospheric CO over the 20 years (Y=-0.008X+449.31). Possible reasons for such a decrease can be related to improved transportation fleet, increased fuel quality, plans for traffic control, promotion of heating systems, and promotion of industrial fuels and factories.

Sludge/TiO2 composite was synthesized from drinking water treatment sludge, as a waste material and TiO2 , by a sol- gel method. Various sludge adsorbent / TiO2 ratios (1:1, 1:2 and 2:1 w/w) were prepared, and characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray Fluorescence (XRF), and BET. The prepared composites were applied successfully for photodegradation of methylene blue (MB) dye from a solution. The photocatalytic degradation of MB dye was investigated using UV irradiation, or UV/H2O2. Initial dye concentration, solution pH, composite dosage, and UV irradiation time were applied to study the optimum conditions for MB degradation. The results revealed the highest MB dye degradation with composite (2:1). It was found that the maximum MB degradation efficiency was at pH=7, 4 h irradiation time, 0.125 g composite dose, and 50 ppm initial dye concentration. MB removal efficiency was 95.7% using UV irradiation, and 99.8% of that using UV/ H2O2. The rate of MB dye degradation followed the first order kinetics. Results from this study offer the best conditions for recycling drinking water treatment sludge, and use it for wastewater treatment.

The aim of this study was to determine the levels of Cd, As, Hg, Pb, and Cr in the edible part of eleven most consumed fish species collected from the north-east coast of Persian Gulf, Iran, during 2017. An inductively coupled plasma atomic emission spectroscopy (ICP-AES) instrument was used to measure the concentration of heavy metals. The results were compared within acceptable limits for human consumption set by various health institutions. The order of heavy metals about total accumulation was Cr>As>Pb> Cd> Hg. The mean heavy metals concentrations of fish species muscle decreased in the order of Acanthopagrus latus> Planiliza subviridis> Lutjanus lemniscatus > Alectis indica> Epinephelus areolatus> Otolithes ruber> Epinephelus chlorostigma> Lethrinus crocineus> Euryglossa orientalis > Cynoglossus arel > Grammoplites suppositus. Probably the difference in the concentration of metals between samples depends on fish species, diet, and habitat. These species were declared to exhibit a low probability of causing non-cancerous diseases. The comparison of the accumulation and hazard risk of consuming the five heavy metals existing in the eleven species that were sampled from the coasts of Khuzestan, Maah-shar Harbour, with the WHO and USEPA guidelines showed that although consuming these fish species does not threaten the consumers' health, pregnant women and children should be cautious about consuming them. The HI was calculated for 70 kg body weight of adults and 14.5 kg body weight of children. The amount of optimal consumption is different for different weights of consumers.

Hydrocarbon storage tanks, the major source of volatile organic compounds (VOCs) emission, have unfavorable effects on atmospheric chemistry and human health. The present study aims at calculating the amount of VOCs’ loss with an emphasis on benzene, toluene, ethylbenzene, and xylene (BTEX). It has been performed by means of TANKs 4.0.9d and WATER9 Software Programs, as well as field measurement for validation. It, then, provides control strategies to reduce the amounts of VOCs in the shipping port area. Emission sources include 32 internal and external floating roof storage tanks, 7 pump houses, and one wastewater treatment pool. Field sampling has been done, using SKC sampling pump and activated carbon adsorption tube according to NIOSH 1501 standard. The obtained samples have been analyzed with FID and GC-MS. Results show that the total emission of VOCs has been equal to 933.25 tons/year, the majority of which (881.74 tons/year ) comes from storage tanks, followed by pump houses and wastewater treatment pool (47.88 and 3.63 tons/year, respectively). BTEX emission includes 1.49 tons/year of benzene, 3.2 tons/year of toluene, 0.57 tons/year of ethylbenzene, and 1.53 tons/year of xylenes. In order to reduce the emission of VOCs from the storage tanks, the paper proposes to change the design of tanks’ roof and sealing. As a result, the total emission of VOCs could be reduced by 18.27%, equivalent to 158.16 tons/year. The total cost of the oil vapors loss is estimated at 253’000 $/year, part of which (i.e., up to 43’000 $/year) could be saved by applying the proposed control strategies.

Currently, the reduction of reactive dyes present in the textile effluent is a big challenge due to the threat to the environment. Existing physical and chemical methods contains many drawbacks. In the present scenario microbial reduction pays much attention and current focus of research. Therefore, the present study isolated dye decolorizing bacterium Exiguiobacterium aurantiacum (TSL7) from activated sludge and identified by molecular techniques and 16S rDNA sequences. Decolorization was not established in Bushnell hass broth composition in accordance with absence of carbon and nitrogen source. The three environmental factors pH, starch and beef extract were selected from Plackett-Burman design experiments. The central composite design was employed to optimize the maximum removal of remazol golden yellow (91.83%) with pH, 6.89, starch, 0.49% (w/v) and beef extract 0.67% (w/v) respectively, These key factors playing a major role in the bacterial dye removal and the interactions were evaluated statistically. The optimal value of significant factors supports to maximize the dye removal competency of isolated bacterium. Thus results exhibited that local salt tolerant bacterium Exiguiobacterium aurantiacum (TSL7) could be a potential candidate for an in situ-bioremediation of inorganic salts abundant textile effluents in the textile industry.