The impact of meteorological parameters on PM10 and visibility during the Middle Eastern dust storms

Air pollution is one of the most pressing issues in populated Middle Eastern cities, in particular for the city of Ahvaz, Iran, imposing deleterious effects on the environment, public health, economy, culture, and other sectors. In this study, we investigate the relationship between meteorological parameters, PM₁₀, AOD, air mass source origin, and visibility during severe desert dust storms (Average_3h PM₁₀ > 3200 µg m^-3) between 2009 and 2012. Six of seven such events occurred between February and March. Interestingly, for the seven cases there was always an alarming PM₁₀ mass concentration peak (137-553 µg m^-3) between 12:00-18:00 (local time) that was 18-24 h before the dominant peak of the storm (3279-4899 µg m^-3). The maximum wind speed over the multi-day periods examined for the dust storms is usually observed 6 h before the alarming PM₁₀ peak. The minimum relative humidity, dew point temperature and air pressure occurred ± 3 h around the time of the alarming PM₁₀ peak. Wind speed was the meteorological parameter that was consistently higher around the time of the first peak as compared to the second peak, with the reverse being true for sea level pressure. Based on four years of daily data in Ahvaz, PM₁₀ was positively correlated with wind speed and air temperature and inversely correlated with sea level pressure and RH. An empirically-derived equation with R² = 0.95 is reported to estimate the maximum PM₁₀ concentration for severe desert dust events in the study region based on meteorological parameters. Finally, AOD is shown to correlate strongly (R² = 0.86) with PM₁₀ during periods with severe desert dust storms in the region.

Life cycle assessment for municipal solid waste management: a case study from Ahvaz, Iran

This study assessed the available status of waste management system in Ahvaz and its impact on the environment, as well as seven other scenarios in order to quantitatively calculate potential environmental impacts by utilizing the life cycle assessment (LCA) method. These scenarios were as follows: scenario 1: landfilling without biogas collection; scenario 2: landfilling with biogas collection; scenario 3: composting and landfilling without biogas collection; scenario 4: recycling and composting; scenario 5: composting and incineration; scenario 6: anaerobic digestion, recycling, and landfilling; scenario 7: anaerobic digestion and incineration. Emissions were calculated by the integrated waste management (IWM) model and classified into five impact categories: resource consumption, global warming, acidification potential, photochemical oxidation, and eco-toxicity. In terms of resource consumption and the depletion of non-renewable resources, the third scenario showed the worst performance due to its lack of any recycling, energy recovery, and conversion to energy. In terms of greenhouse gas emissions and the effect on global warming, scenario 1 and scenario 2 showed that disposing the whole amount of waste resulted in the most amount of greenhouse gases produced. Moreover, 50% gas and energy recovery from landfills, in comparison with the non-recovery method, reduced the index of global warming by 12%. Finally, scenarios which were based on producing energy from waste showed a reasonably positive performance in terms of greenhouse gases emissions and the influence on global warming.

Phytoremediation potential of vetiver grass irrigated with wastewater for treatment of metal contaminated soil

A field experiment was conducted to understand the potential of vetiver grass (Vetiveria zizanioides) in heavy metal uptake from the soil and wastewater. Four main irrigation treatments including T₁ (treated industrial wastewater), T₂ (1:1 ratio of municipal:industrial wastewater), T₃ (treated municipal wastewater) and T₄ (fresh water) were applied. Moreover, the effect of arbuscular mycorrhizal fungus (AMF), Glomus mosseae, on plant growth and heavy metal concentration was evaluated. Three main criteria including bioconcentration factor (BCF), translocation factor (TF) and heavy metal uptake were applied to assess the potential of vetiver grass in accumulation and translocation of heavy metals to aerial parts. The highest concentration of heavy metals was found in plant and soil irrigated with T₁ treatment followed by T₂, T₃ and the lowest concentrations were found in T₄ treatment. Irrigation with treated municipal wastewater led to a significant increase in plant biomass and heavy metal uptake compared to other treatments. In T₁ treatment (industrial wastewater), vetiver grass caused a significant decrease in Zn, Fe, Cu, Cd and Pb concentrations in soil as compared to no-plant treatment (without planting vetiver grass). Therefore, vetiver grass, irrigated with treated industrial wastewater, is a promising method for the development of urban and industrial green space.

Organo-Clay/Anthracite Filtration for Oil Removal

Abstract

A bentonite organo-clay/anthracite mixture in the granular form (EC-100) was used in filtration (column) studies in treating four representative oil-in-water emulsions. The oil-in-water emulsions used were as follows: Standard Mineral Oil (SMO); Kutwell 45 (KUT) and Valcool (VAL), two cutting oils; and Refinery Effluent (RE) from the Co-operative Oil Refinery, Regina, Saskatchewan. The concentrations of oil in the oily waters varied from 8.3 to 69.3 mg/L. Eight-hour column studies were conducted in a 19 mm ID, 450 mm/1200 mm long cast acrylic pipe with an organo-clay/anthracite depth of 300 mm/1,000 mm. The SMO, KUT, and VAL oil-in-water emulsions were pumped into the column at four flow rates of 3, 6, 9, and 12 mL/min (0.3, 0.5, 0.8, and 1.0 gpm/ft2, respectively). Column breakthrough studies were conducted in a 19 mm ID, 1,200 mm long cast acrylic pipe using the organo-clay/anthracite mixture of 1,000 mm depth. The study was conducted for SMO, KUT, VAL and RE oil-in-water emulsions with a flow rate of 12 mL/mim (1 gpm/ft2). The eight-hour column tests with 300 mm bed depth and all oil-in-water emulsions indicated that generally, the oil removal efficiencies decreased with an increase in flow rate. The percentage reduction in oil removal efficiency was 29 and 37 for SMO, 51 and 59 for KUT, and 9 and 57 for VAL when the flow rate was increased from 3 mL/min to 6 and 9 mL/min, respectively. The results of the eight-hour experiments with a 1,000 mm depth of organo-clay/anthracite bed and with a flow rate of 12 mL/min showed that oil removal efficiency for SMO, KUT, and VAL varied between 65 and 70﹪. In the ase of RE, which is a treated and highly stable emulsion, the oil removal efficiency was found to be 99.5﹪. The results from the breakthrough studies clearly indicated that the Thomas equation provides a reasonable fit of the data. The oil-sorption capacities (x/m) based on a mass balance analysis were found to be 0.0036, 0.0019, 0.0015, and 0.0018 for SMO, KUT, VAL, and RE, respectively. The analysis of the breakthrough data using the Thomas model resulted in similar values of x/m. The results also showed that uptake of oil by an organo-clay/anthracite mixture can well be described by a simple equation involving time, such as Weber and Morris model.

Introduction

Organo-clay can be described as modified bentonite. The modification process becomes complete by exchanging the inorganic cations (sodium and calcium) present on the surfaces and interlayer spaces of clays by the nitrogen end of a Quaternary amine, and, thus, changing the hydrophilic nature of clays to organophilic(1, 2).

As a result, organo-clays become excellent sorbents for hydrophobic organics such as oil(3). An advantage of organo-clay compared to other sorbents is that it can selectively remove organic pollutants from contaminated waters.

The sorptive nature of bentonite organo-clay for some organic pollutants has been extensively studied(4-8). However, the effectiveness of organo-clay/anthracite mixture as a filter in the removal of oil from water has not been studied extensively.