Emission patterns of acrylonitrile and styrene around an industrial wastewater treatment plant in Iran

The uncontrolled releases of volatile organic compounds (VOCs) from wastewater treatment plants (WWTPs) have been highly concerned due to the associated public health risks. In petrochemical industries, WWTPs are responsible for various organic compound emissions into the atmosphere, which can considered as the main source of VOCs emission in such industries. The typical high-strength petrochemical wastewater is generated from an acrylonitrile–butadiene–styrene (ABS) resin manufacturing plant that usually needs pretreatment before discharging to the main WWTP. The objective of this study was to investigate the emissions and fates of acrylonitrile (ACN) and styrene (STM) through wastewater pretreatment units operated in an ABS manufacturing plant. In this study, the emission rates of ACN and STM were estimated by means of EPA’s Water9 emission model. Subsequently, the emission rates were used as the input data of AERMOD model to simulate the atmospheric behaviors of emitted ACN and STM. The results of Water9 model showed that 57 and 81 % of influent ACN and STM are emitted to the air through pretreatment units, respectively. For both of them, the equalization basin had the major portion of emission to the atmosphere. The concentration distribution profiles of ACN and STM resulted from AERMOD model indicted that the concentration of STM was lower than EPA reference concentration (RfC); however, the higher concentration of ACN (higher than RfC) occurred near the WWTP as well as the neighbor ambient.     

Diagnostic analysis of offensive odorants in a large municipal waste treatment plant in an urban area

A diagnostic study was conducted to examine the effectiveness of malodor removal from a large-scale municipal waste treatment plant in an urban area. To this end, the odor pollution status was investigated from a total of 16 spots in the treatment facility to cover the dual treatment lines consisting of regenerative thermal oxidation (first stage) and a wet chemical scrubber (second stage). As a simple means to learn more about the odorant removal efficiency of different treatment units, samples collected from ambient spots as well as before and after each treatment unit were analyzed for 22 key offensive odorants (i.e., reduced sulfur compounds, carbonyl compounds, nitrogenous compounds, volatile organic compounds, and fatty acids) along with dilution-to-threshold ratios based on the air dilution sensory test. The removal patterns differed greatly between different odorant groups across different processing units. The effectiveness of this dual treatment system was optimized for such odorants as hydrogen sulfide and ammonia, while it was not the case for others (e.g., some aldehydes and organic acids). The results thus suggest the need for the validation of the efficiency in many types of odor processing units and for establishing new control techniques to cover a list of odorants un-subordinate to preexisting methods.     

Study of anaerobic biodegradation of pharmaceuticals and personal care products: application of batch tests

This study evaluated three types of pharmaceuticals and personal care products (methylparaben, ibuprofen and triclosan) at concentration levels of 300, 500, 1000 and 2000 µg/L by implementing batch tests using anaerobic processes and granular biomass. The study aimed to identify the mechanisms of biodegradation and sorption in the degradation of these compounds. The inoculum was granular sludge from a laboratory-scale anaerobic reactor. The characterization results of the inoculum showed an anaerobic biomass with high activity, good sedimentation and a high percentage of organic matter. The results of the removal of the pollutants showed high degradation percentages for methylparaben (close to 99%), with negligible sorption in the sludge. The results also showed insignificant ibuprofen sorption but removal close to 0%. Triclosan showed high biomass sorption and low biodegradation. In addition, at the concentrations tested, none of the compounds had a negative or inhibitory effect on the microbial populations of the system.     

The influence of the Tula,Hidalgo complex on the air quality of the Mexico City Metropolitan Area

Using an air quality model, this study shows how emissions from the “Miguel Hidalgo” refinery of Petróleos Mexicanos (Pemex) and the thermoelectric plant “Francisco Pérez Ríos” of the Comisión Federal de Electricidad (CFE, Federal Electricity Commission) in Tula, Hidalgo influence the atmosphere of the Mexico City Metropolitan Area (MCMA). The model couples meteorology and chemistry. The weather scenario encompasses the period from October 20-28, 2005. Two scenarios are compared: the first assumes a 40% reduction in emissions of NO_x, SO₂, and volatile organic compounds (VOCs) from the Tula complex (reduction scenario), and the second considers the scenario without reduction (baseline scenario). The model is compared with measurements of the Red Automática de Monitoreo Atmosférico (Automatic Environmental Monitoring Network). We observe that under certain weather conditions, the energy sector of Tula, Hidalgo affects the air quality in the MCMA. The reduction scenario is effective in reducing SO₂ concentrations; however, despite a 40% decrease in the emissions of ozone precursors, their concentrations in the MCMA did not decrease.     

Biomass burning — a review of organic tracers for smoke from incomplete combustion

Biomass combustion is an important primary source of particles with adsorbed biomarker compounds in the global atmosphere. The introduction of natural product organic compounds into smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular compositions of organic matter in smoke particles are highly variable, the molecular tracers are generally still source specific. Dehydroabietic acid is typically the major tracer for conifer smoke in the atmosphere. Degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin) are also excellent tracers. Additional markers of thermally-altered and directly-emitted natural products in smoke have been defined which aids the assessment of the organic matter types and input from biomass combustion to aerosols. The precursor to product approach of compound characterization by organic geochemistry has also been applied successfully to provide source specific tracers for studying the chemistry and dispersion of ambient aerosols and the intermingling of natural with anthropogenic emissions and with smoke plumes. A brief review of the organic matter composition in aerosols derived from the major sources is also given, with emphasis on the detection of biomass burning components. These major sources are the natural background from biogenic detritus (e.g. plant wax, microbes, etc.) and anthropogenic particle emissions (e.g. oils, soot, synthetics, compounds, etc.). The emissions of organic constituents in coal smoke particulate matter are also reviewed and depend on combustion temperature, ventilation, burn time, and coal rank (geologic maturity). The components of peat and brown coal and to a lesser degree semi-bituminous coal consist mainly of hydrocarbons, biomarkers, and aromatic components, quite similar to burning of contemporary biomass. Dispersion from the source and long range transport of smoke particulate matter with the associated organic compounds is also discussed.     

Volatile organic compounds emitted from hardwood drying as a function of processing parameters

During the drying of wood, volatile organic compounds are emitted. These emissions contribute, in the presence of nitrogen oxides and sunlight, to the formation of ground level ozone and other harmful photo-oxidants. Emissions of volatile organic compounds from the drying of birch sawdust in a spouted bed were analyzed with a flame ionization detector and with a gas chromatograph-mass spectrometer. A D-optimal model of the emissions showed that the emissions increased exponentially with decreasing sawdust moisture content and that the final sawdust moisture content was influencing emissions about twice as much as the inlet drying medium temperature and the month of logging. At inlet temperatures of 140–170 °C, the emissions increased steeply when the moisture content of the sawdust reached 10%, whereas an inlet temperature of 200 °C caused a surge of thermal degradation products at 15% moisture content. The results of this study should help to reduce the emissions of volatile hydrocarbons during the drying of hardwood sawdust and wood chips.     

The fate and behavior of selected endocrine disrupting chemicals in full scale wastewater and sludge treatment unit processes

Endocrine disrupting chemicals are discharged into the environment mainly through wastewater treatment processes. There is a need for better understanding of the fate of these compounds in the unit processes of treatment plant to optimise their removal. The fate of oestrone, 17β-estradiol, 17α-ethinyestradiol and nonylphenol in the unit processes of full scale wastewater treatment plants in the UK, including activated sludge plant, oxidation ditch, biofilter and rotating biological contactor were investigated. The overall removal efficiencies of all the compounds ranged from 41 %to 100%. The removals were predominantly during the secondary biological treatment with the rates of removal related to the nitrification rates and the sludge age. The removal efficiency of the treatment processes were in the order activated sludge > oxidation ditch > biofilter > rotating biological contactors. Activated sludge plant configured for biological nutrient removal showed better removal of the endocrine disrupting chemicals compared to conventional activated sludge plant effluents. Tertiary treatment was also significant in the removal process through solids removal. Overall mechanisms of removal were biodegradation and sorption unto sludge biomass. Phytoremediation was also significant in the removal processes. The endocrine disrupting chemicals persisted in the anaerobic sludge digestion process with percentage removals ranging fro 10–48 %. Sorption of the endocrine disrupting chemicals onto the sludge increased with increasing values for the partitioning coefficients and the organic carbon contents of the sludge.     

Cyclic organosilicon compounds in ambient air in Guangzhou,Macau and Nanhai,Pearl River Delta

Silicon is present in the Earth's atmosphere as a consequence of several processes including the release of Si compounds from anthropogenic sources, but little information is available on airborne Si compounds of anthropogenic origins. In this study ambient air samples from Guangzhou, Macau and Nanhai in the Pearl River Delta, South China were collected by sorbent tubes for the determination of concentrations of volatile organosilicon compounds. Samples were analysed by thermal desorption followed by a GC–MSD technique for compound identification and quantitative analysis. Hexamethylcyclotrisiloxane (D3) and octamethylcyclotetrasilo-xane (D4) were found to be the two dominant organosilicon compounds in the air. In Guangzhou, higher total D3 and D4 concentrations were observed in the industrial area, landfill and waste water treatment plant, while the lowest levels occurred in suburb forest. Two types of linear correlation between D3 and D4 were found in Guangzhou samples, indicating different sources of these organosilicon compounds. Samples in Macau and Nanhai showed different D3 and D4 relationships from the samples in Guangzhou.     

Surfactant-enhanced remediation of contaminated soil: a review

Extracting aqueous solutions with or without additives are employed to solubilize contaminants in soil. Since water solubility is the controlling removing mechanism, additives are used to enhance efficiencies. These additives can reduce the time to treat a site compared to the use of water alone. Additives must be of low toxicity and biodegradable. The research in this area has focussed mainly on halogenated volatile organic compounds (VOCs) and is still quite limited for metal removal. Additives include surfactants, organic and inorganic acids, sodium hydroxide, which can dissolve organic soil matter, water-soluble solvents such as methanol, displacement of cations with nontoxic ones, complexing agents such as EDTA, acids in combination with complexing agents or oxidizing/reducing agents. Cationic, anionic and nonionic surfactants are particularly used for soil washing or flushing. They contain both hydrophobic and hydrophilic portions, making them ideal for solubilization of hydrophobic compounds. Numerous studies have indicated that surfactants enhance recoveries of non-aqueous phase liquids (NAPLs). There have also been indications that pretreatment of soil with surfactant washing to solubilize hydrophobic compounds such as PAHs enhances biodegradation of these contaminants. A few in situ field studies have been performed with surfactants. Large-scale treatment has been done mostly for organic removal. Soil pH, soil type, cation exchange capacity (CEC), particle size, permeabilities and contaminants all affect removal efficiencies. High clay and organic matter contents are particularly detrimental. Understanding the chemistry of the binding of the contaminant and the hydrogeology of the site are very important. Once the water is pumped from the soil, it must be extracted and then treated to remove the hydrocarbons and metals. Several technologies exist such as sodium hydroxide or sodium sulfide precipitation, ion exchange, activated carbon adsorption, ultrafiltration, reverse osmosis, electrodialysis and biological processes. Recycling of the surfactants is desired to decrease treatment costs.

This paper will provide an overview of the laboratory research, field demonstration and full-scale application of surfactants for the remediation of contaminated soil. The majority of pilot scale in situ flushing tests, particularly in the United States, have involved the use of surfactants and co-solvents. There are only a few full-scale projects however. Recent laboratory scale efforts by the authors concerning the use of biosurfactants, biologically produced surfactants, to enhance the removal of copper, cadmium and zinc from contaminated soils and sediments are discussed. Three types of biosurfactants were evaluated for their effectiveness. They included a lipopeptide called surfactin from Bacillus subtilis, a rhamnolipid from Pseudomonas aeruginosa and a sophorolipid from Torulopsis bombicola. The results indicated the feasibility of removing the metals with the anionic biosurfactants even though the exchangeable fractions were not significant.     

TECHNICAL NOTE An experimental investigation of air flow patterns in saturated soils during air sparging

Air sparging is an emerging method used to remediate saturated soils and groundwater that have been contaminated with volatile organic compounds (VOCs). During air sparging, air is injected into the subsurface below the lowest known depth of contamination. Due to buoyancy, the injected air will rise through the zone of contamination. Through a variety of mechanisms, including volatilization and biodegradation, the air will serve to remove or help degrade the contaminants. The contaminant-laden air will continue to rise towards the ground surface, eventually reaching the vadose zone, where the vapours are collected and treated using a soil vapour extraction (SVE) system.Air sparging performance and ultimately contaminant removal efficiency is highly dependent on the pattern and type of subsurface air flow. This paper presents the results of a laboratory experimental study which investigated the injected air flow pattern development within an aquifer simulation apparatus. The test apparatus consisted of a tank measuring 61 cm long by 25.4 cm wide by 38.1 cm high. The apparatus was equipped with one air injection well and two vapour extracton wells. Three different soils were used to simulate different aquifer conditions, including a sand, a fine gravel and a medium gravel. Experiments were performed with different injected air pressures combined with different vacuum and groundwater flow conditions. Experiments were also conducted by injecting air into simulated shallow aquifers with different thicknesses. The air flow patterns observed were found to depend significantly on the soil type, groundwater flow conditions and system controls, including injected air pressure, flow rate and applied vacuum. © Rapid Science Ltd. 1998     

Impact of activated sludge acclimation on the biodegradation of toluene absorbed in a hydrophobic ionic liquid

Classical hydrophobic ionic liquids such as 3-butyl-1-methylimidazolium bis(trifluoroethylsulfonyl)imide or 3-butyl-1-methylimidazolium hexafluorophosphate application, as a non-aqueous liquid phase in a two-partitioning bioreactor to biodegrade hydrophobic volatile organic compounds by activated sludge, have been already reported in the literature, especially when the activated sludge was beforehand acclimated to the targeted volatile organic compound. In this study, four hydrophobic ionic liquids were used as non-aqueous liquid phase in a two-phase partitioning bioreactor to biodegrade toluene using non-acclimated activated sludge. The preliminarily results allowed to select two ionic liquids, 1-octylisoquinolinium bis(trifluoromethylsulfonyl)imide and allyl-diethylsulfonium bis(trifluoromethylsulfonyl)imide. The activated sludge was acclimated to both toluene and the considered ionic liquid. The results were compared to those obtained with non-acclimated activated sludge. The use of non-acclimated activated sludge for toluene biodegradation led to long lag times and low biodegradation rates. Thus, the acclimation to toluene improved the biodegradation rates; however, acclimation to both toluene and ionic liquid did not result in a significant improvement in the biodegradation rate compared to an acclimation to toluene alone. The activated sludge acclimation had a positive impact on toluene biodegradation and allowed to totally overcome the inhibitory effect of the presence of ionic liquid. The most relevant acclimation strategy seems to be a prior acclimation to toluene, whereas acclimation to the non-aqueous liquid phase can be achieved during the culture, namely by performing successive batches for instance, or a continuous operation.     

The Air-Coastal Sea Chemical Exchange: A Case Study on the New Jersey Coast

The coastal marine atmosphere adjacent to large urban and industrial centers is in general strongly impacted by pollution emissions, resulting in high loading of pollutants in the ambient air. Among the airborne substances are certain trace elements from a variety of emission sources that can serve as micronutrients to marine organisms in coastal waters. High concentrations of such elements in coastal air can result in enhanced air-to-sea deposition fluxes to coastal waters. They could also be transported over the open ocean, affecting the composition of the remote marine atmosphere and then ocean ecosystems. To provide better understanding of the extent of air-to-sea deposition processes on the New Jersey coast, a heavily polluted coastal region on the US East Coast, a synthesis of observation data was carried out for selected trace elements, including Fe, Cd, Cr and Cu, derived from measurements of both size-segregated and bulk aerosol particles, as well as precipitation around the New Jersey coast. The atmospheric input of Hg was also estimated based on measurement data. Results indicated that the total deposition fluxes of most trace elements were higher in Northern coastal NJ compared to Southern coastal NJ, reflecting the differences in the source strengths of these element emissions between the two coastal regions. Dry deposition processes were more significant for common dust-derived elements, particularly Fe and Al, compared with their wet deposition fluxes. However, the processes of precipitation scavenging appeared to be more important for the elements that were often enriched in fine particles including Zn, Cu, Pb and Ni. The removal of Hg from the ambient air was overwhelmingly dominated by atmospheric wet deposition. In the future, atmospheric measurements at more sites on the NJ coast should be performed simultaneously to reduce the spatial and temporal uncertainties associated with atmospheric deposition fluxes estimated in this study.     

Determination of ammonia removal from aqueous solution and volumetric mass transfer coefficient by microwave-assisted air stripping

In this study, the removal of ammonia from synthetically prepared ammonia solution at pH 11 was investigated by using microwave radiation heating. Initially, conventional and microwave radiation heating were compared with respect to ammonia removal efficiency and overall volumetric mass transfer coefficient at five different temperatures. Overall volumetric mass transfer coefficient was calculated from the material balance for ammonia at unsteady-state condition. The effects of temperature, initial ammonia concentration, air flow rate, stirring speed, and microwave radiation power on both ammonia removal efficiency and overall volumetric mass transfer coefficient in liquid phase were also examined. The results of the experiments revealed that microwave-assisted air stripping allowed to the higher ammonia removal efficiency and overall volumetric mass transfer coefficient value compared to the conventional heating air stripping. Additionally, temperature and air flow rate were determined as the most substantial parameters affecting both ammonia removal efficiency and overall volumetric mass transfer coefficient value.     

Soiling of limestone in an urban environment characterized by heavy vehicular exhaust emissions

The inorganic and organic chemical composition of weathering sulphate patinas on the limestone walls of Emmanuel College, Cambridge, UK, have been analysed by FT-IR spectroscopy, pyrolysis gas-chromatography/mass spectrometry and scanning electron microscopy. The College location is characterized by heavy vehicular exhaust emissions including those from diesel powered public transport vehicles due to its proximity to the main Cambridge coach station. A complex mixture of gaseous and particulate air pollutants are found deposited in the weathering patinas including organic compounds (such as PAHs), which represent markers for present-day vehicular pollution. Slight differences in composition between patinas collected at different heights on the building facades with, in particular, more evidence for a biogenic overprint in samples collected at roof level as opposed to ground (street) level are found. Analytical results confirm how building stones in urban areas acted in the past and still do today as passive repositories for any kind of gaseous and particulate air pollutant present in the surrounding atmosphere; accordingly, weathering patinas are slowly changing their composition to accommodate new classes of present-day air pollutants.     

The effects of trust in government on earthquake survivors’ risk perception and preparedness in China

Natural Hazards - The accumulation of volatile organic compounds (VOCs) in ambient air affects air quality through the generation of surface level ozone and secondary organic aerosol. A study of...     

Distribution of volatile organic compounds around a polluted river

The objectives of this study were to investigate the species and the concentration distribution of volatile organic compounds around a heavily polluted river. Air samples were collected seasonally at different locations near the polluted river. Samples were then analyzed by gas chromatography (electron capture detector for chlorinated organic compounds and flame ionization detector for ordinary hydrocarbons). The data was then analyzed by the statistical product and service solutions software. The results showed that total of 26 species of volatile organic compounds were identified. Each individual had its own concentration distribution pattern at different seasons and aliphatic volatile organic compounds displayed much higher concentrations than most benzenoic volatile organic compounds. In aliphatic volatile organic compounds, 1,2-dibromo-3-chloropropane, hexachlorobutadiene and 1,2-dibromoetane had much higher concentrations at the nearby environment of the river and they have been claimed to be carcinogenic to some experimental animals and possibly to human. Therefore, It is in doubt that for a long term, the volatile organic compounds evaporating out of the stream may threat the health of the residents living very close to the river. The concentrations of tetrachloroethene, 1,1,2,2-tetrachloroethane, hexachlorobutadiene, dibromoetane, dichlorobenzene and sec-butylbenzene appeared at the nearby environment of the river had significant correlations (P < 0.05) with those of each other or many other volatile organic compounds.     

Evidence for bacterial degradation of hydrocarbons in uranium deposits

The biodegradation of free hydrocarbons migrated in reservoir faaes has often been observed in petroleum exploration. This bacterial alteration is characterized by the progressive removal of different classes of hydrocarbons. One of the most important consequences of biodegradation is the reduction of sulphate, as noted in several Pb-Zn deposits. Biodegradation of oils spatially associated with uranium deposits has also been observed in Lodeve (France), Grand Canyon (Arizona, USA), Temple Mountain (Utah, USA) and leads to the transformation of fluid oils into solid bitumens. Within this study emphasis has been laid on the relationships between the effects of biodegradation on organic matter (oxidation or aromatization) and the nature of aqueous solutions analysed in fluid inclusions trapped in authigenic minerals. Different mechanisms are proposed to explain the transformations of organic matter during biodegradation and their possible links with ore-forming processes.     

Impact of the ambient air quality due to the dispersion of non-methane organic compounds from Barka Landfill

This study used the CALPUFF modeling system to study the impact of an area’s geophysical and meteorological conditions on the dispersion of non-methane organic compounds (NMOCs) into the atmosphere from the 17-year-old Barka Landfill. Barka Landfill is located in Barka, Batinah, in the north of the Sultanate of Oman. It receives waste from nearby regions such as Nakhal, Seeb, and Wadi Al-Maawel, affecting the town of Barka with landfill gas (LFG) pollution. The present study was conducted to evaluate the impact of the air dispersion of one group of NMOC gases on Barka and the region around it. The top five values of the concentrations with different average time periods, namely 1, 3 and 23 h, were compared with the allowable emission rate defined by the US Environmental Protection Agency (EPA). The results demonstrated that the present integrated modeling system (consisting of a 3D diagnostic CALMET model and Lagrangian puff dispersion CALPUFF model) could be utilized as a useful tool for evaluating the top five peak values of the NMOC emissions of the different time periods.     

Remediation of saturated Shanghai sandy silt contaminated with p-xylene using air sparging

Air sparging is an effective technique for the remediation of soil and groundwater polluted by volatile organic compounds. In this paper, this technique was investigated by conducting air-sparging test in the laboratory on the Shanghai sandy silt that was artificially contaminated with p-xylene. A test tank was designed for this purpose. During the air-sparging process, aqueous p-xylene solutions were extracted from the observation holes, and their concentrations were quantified by the spectrophotometric detection method. The mechanism of mass transfer process of p-xylene in the vicinity of sparging well and the remediation of the contaminated groundwater by air sparging were explored. The results showed that the removal zone of the p-xylene was mainly located within a radius of about 20?cm around the air injection well, with 90?% p-xylene removed after 20-day air sparging. Within the initial 5-day sparging, the concentration of p-xylene decreased rapidly in the mass transfer zone. By contrast, in the area far from the injection well, the p-xylene concentration decreased evenly and slowly. Thus, the remediation of contaminated soil and groundwater by air sparging is space?Ctime dependent. For further analysis, the adsorption of silt was taken into account, and the distribution coefficient, K _d , was introduced to the modified Shackleford??s mass transfer model. The comparison between the simulated and measured results indicates that the modified model can satisfactorily describe the p-xylene mass transfer observed in this study.     

Co-contamination of water with chlorinated hydrocarbons and heavy metals: challenges and current bioremediation strategies

Chlorinated hydrocarbons can cause serious environmental and human health problems as a result of their bioaccumulation, persistence and toxicity. Improper disposal practices or accidental spills of these compounds have made them common contaminants of soil and groundwater. Bioremediation is a promising technology for remediation of sites contaminated with chlorinated hydrocarbons. However, sites co-contaminated with heavy metal pollutants can be a problem since heavy metals can adversely affect potentially important biodegradation processes of the microorganisms. These effects include extended acclimation periods, reduced biodegradation rates, and failure of target compound biodegradation. Remediation of sites co-contaminated with chlorinated organic compounds and toxic metals is challenging, as the two components often must be treated differently. Recent approaches to increasing biodegradation of organic compounds in the presence of heavy metals include the use of dual bioaugmentation; involving the utilization of heavy metal-resistant bacteria in conjunction with an organic-degrading bacterium. The use of zero-valent irons as a novel reductant, cyclodextrin as a complexing agent, renewable agricultural biosorbents as adsorbents, biosurfactants that act as chelators of the co-contaminants and phytoremediation approaches that utilize plants for the remediation of organic and inorganic compounds have also been reported. This review provides an overview of the problems associated with co-contamination of sites with chlorinated organics and heavy metals, the current strategies being employed to remediate such sites and the challenges involved.