Removal of aqueous-phase polynuclear aromatic hydrocarbons using aspen wood fibers

Roadway runoff derived polynuclear aromatic hydrocarbons (PAHs) impact the quality of surface and ground water. Inexpensive aspen wood fibers have been investigated as a means to remove dissolved PAH under laboratory conditions. Our isotherm experiments demonstrated that the uptake of naphthalene, fluorene, anthracene, and pyrene required up to 12.5 days to reach equilibrium. Aspen wood-water sorption coefficients, Kww, were linearly correlated to octanol-water partition coefficients and the molecular weight of the studied PAH compounds. The correlation between Kww and molecular weight was the most significant. Column experiments were carried out to study the sorption and desorption of fluorene, anthracene, and pyrene under dynamic conditions. The results indicate linear sorption, but non-linear desorption behavior. The degree of desorption was inversely correlated to a compound's hydrophobicity. Flow interruption experiments showed that sorption and desorption was rate limited. A mass balance of the sorption and desorption tests indicated that sorptive uptake exceeded desorptive release over a given number of pore volumes. Further, absolute mass-removal efficiency increased with the molecular weight and hydrophobicity of the PAH compound. Batch and column studies demonstrated that aspen wood has the potential to become an effective remedial agent for PAH in stormwater runoff or other PAH contaminated waters.     

Sustainable oil and grease removal from synthetic stormwater runoff using bench-scale bioretention studies.

One of the principal components of the contaminant load in urban stormwater runoff is oil and grease (O&G) pollution, resulting from vehicle emissions. A mulch layer was used as a contaminant trap to remove O&G (dissolved and particulate-associated naphthalene, dissolved toluene, and dissolved motor oil hydrocarbons) from a synthetic runoff during a bench-scale infiltration study. Approximately 80 to 95% removal of all contaminants from synthetic runoff was found via sorption and filtration. Subsequently, approximately 90% of the sorbed naphthalene, toluene, oil, and particulate-associated naphthalene was biodegraded within approximately 3, 4, 8, and 2 days after the event, respectively, based on decreases in contaminant concentrations coupled with increases of microbial populations. These results indicate the effectiveness and sustainability of placing a thin layer of mulch on the surface of a bioretention facility for reducing O&G pollution from urban stormwater runoff.     

Effectiveness of Smokeless Ashtrays

Abstract

Most environmental tobacco smoke (ETS) issues from the tips of smoldering cigarettes between puffs. Smokeless ashtrays are designed to reduce ETS exposure by removing particulate and/or gas-phase contaminants from this plume. This paper describes an experimental investigation of the effectiveness of four smokeless ashtrays: two commercial devices and two prototypes constructed by the authors. In the basic experimental protocol, one or more cigarettes was permitted to smolder in a room. Particulate or gas-phase pollutant concentrations were measured in the room air over time. Device effectiveness was determined by comparing pollutant concentrations with the device in use to those obtained with no control device. A lung deposition model was applied to further interpret device effectiveness for particle removal. The commercial ashtrays were found to be substantially ineffective in removing ETS particles because of the use of low-quality filter media and/or the failure to draw the smoke through the filter. A prototype ashtray using HEPA filter material achieved better than 90% particle removal efficiency. Gasphase pollutant removal was tested for only one prototype smokeless ashtray, which employed filters containing activated carbon and activated alumina. Removal efficiencies for the 18 gas-phase compounds measured (above the detection limit) were in the range of 70 to 95%.     

The fate of the aqueous phase polycyclic aromatic hydrocarbon fraction in a detention pond system

The concentration of dissolved polycyclic aromatic hydrocarbons (PAH) in influent, effluent, and within a detention pond system was measured. The "soluble fraction" was operationally defined as the PAHs in solution that passed through a 1.2 μm filter. The results show that influent and effluent PAH concentrations were similar, indicating that dissolved PAH moved essentially unhindered through the detention pond system. In general, low molecular weight PAH were present at the highest concentrations and the highest PAH concentrations were measured in Summer. Also, year-to-year variations in PAH concentration were observed. At the end of sufficiently large storms, the pond was comparably unpolluted. During dry periods, the dissolved PAH concentration rose, possibly due to evapoconcentration and by partitioning of PAH from trapped contaminated sediment in the detention pond system. This study provides evidence that aqueous-phase PAH concentrations in runoff water were relatively unaffected by the passage through a conventional detention pond system.     

Capillary GC-MS analysis of PAH emissions from combustion of peat and wood in a hot water boiler

A preliminary investigation has been made on the emissions of Polynuclear Aromatic Hydrocarbons (PAH) when burning wood chips and peat in a modified commercial hot water boiler. The amount of the investigated eighteen PAH that were filter trapped from peat combustion averaged 2.7 times greater than that from wood combustion per cubic meter flue gas. The total emitted amount (particulate plus gas phase PAH) was 9.7 times greater than from wood combustion. The corresponding values for benzo(a)pyrene only were 1.7 and 3.5 times greater, respectively. The comparison of PAH emitted by the combustion of wood and peat showed a pronounced tendency towards the emission of high molecular weight PAH by the latter.Particulate phase-gas phase distribution ourves are presented for PAH in the boiling point range 336°C – 525°C. In addition, the emission of a polynuclear aromatic ketone is shown.     

Characterizing the passage of personal care products through wastewater treatment processes.

Wastewater treatment facilities use secondary treatment to stabilize the effect of discharged effluent on receiving waters by oxidizing biodegradable organic matter and reducing suspended solids and nutrients. The process was never specifically intended to remove trace quantities of xenobiotics, such as endocrine-disrupting compounds (EDCs) and pharmaceuticals and personal care products (PPCPs). Nevertheless, European studies performed at bench-scale or at small facilities have demonstrated that a critical minimum solids retention time (SRT) can achieve good reduction of many EDCs and pharmaceuticals. The objective of this study was to expand these findings to the removal performance for 20 PPCPs commonly found in the influent to full-scale facilities operating in the United States. The participating plants use SRT conditions ranging from 0.5 to 30 days and include facility capacities ranging from 19 000 m3/d (5 mgd) to greater than 1 136 000 m3/d (300 mgd). Two pilot membrane bioreactors were also included in the study. The 20 PPCPs were categorized into nine bin combinations of occurrence frequency and treatment reduction performance. While most compounds were well removed, galaxolide (a musk fragrance) occurred frequently and was resistant to removal. A minimum critical SRT, defined as the minimum SRT, needed to consistently demonstrate greater than 80% removal (SRT80), was compound-dependent, with most compounds removed at 5 to 15 days and a small group requiring longer SRTs. From limited data, no additional removal could be attributed to the use of membrane bioreactors, media filters, or longer hydraulic retention times. Reverse osmosis was effective in removing any remaining compounds.     

The ability of biologically based wastewater treatment systems to remove emerging organic contaminants—a review

Biologically based wastewater treatment systems are considered a sustainable, cost-effective alternative to conventional wastewater treatment systems. These systems have been used and studied for the treatment of urban sewage from small communities, and recently, it has been reported that they can also effectively remove emerging organic contaminants (EOCs). EOCs are a new group of unregulated contaminants which include pharmaceutical and personal care products, some pesticides, veterinary products, and industrial compounds among others that are thought to have long-term adverse effects on human health and ecosystems. This review is focused on reporting the ability of biologically based wastewater treatment systems to remove EOCs and the main elimination mechanisms and degradation processes (i.e., biodegradation, photodegradation, phytoremediation, and sorption) taking place in constructed wetlands, ponds, and Daphnia and fungal reactors.     

Identification and removal of polycyclic aromatic hydrocarbons in wastewater treatment processes from coke production plants

Identification and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated at two coke plants located in Shaoguan, Guangdong Province of China. Samples of raw coking wastewaters and wastewaters from subunits of a coke production plant were analyzed using gas chromatography–mass spectrometry (GC/MS) to provide a detailed chemical characterization of PAHs. The identification and characterization of PAH isomers was based on a positive match of mass spectral data of sample peaks with those for PAH isomers in mass spectra databases with electron impact ionization mass spectra and retention times of internal reference compounds. In total, 270 PAH compounds including numerous nitrogen, oxygen, and sulfur heteroatomic derivatives were positively identified for the first time. Quantitative analysis of target PAHs revealed that total PAH concentrations in coking wastewaters were in the range of 98.5?±?8.9 to 216?±?20.2 μg/L, with 3-4-ring PAHs as dominant compounds. Calculation of daily PAH output from four plant subunits indicated that PAHs in the coking wastewater came mainly from ammonia stripping wastewater. Coking wastewater treatment processes played an important role in removing PAHs in coking wastewater, successfully removing 92 % of the target compounds. However, 69 weakly polar compounds, including PAH isomers, were still discharged in the final effluent, producing 8.8?±?2.7 to 31.9?±?6.8 g/day of PAHs with potential toxicity to environmental waters. The study of coking wastewater herein proposed can be used to better predict improvement of coke production facilities and treatment conditions according to the identification and removal of PAHs in the coke plant as well as to assess risks associated with continuous discharge of these contaminants to receiving waters.     

Removal of polycyclic aromatic hydrocarbons from aged-contaminated soil using cyclodextrins: experimental study

The removal of polycyclic aromatic hydrocarbons (PAHs) from soil using water as flushing agent is relatively ineffective due to their low aqueous solubility. However, addition of cyclodextrin (CD) in washing solutions has been shown to increase the removal efficiency several times. Herein are investigated the effectiveness of cyclodextrin to remove PAH occurring in industrially aged-contaminated soil. Beta-cyclodextrin (BCD), hydroxypropyl-beta-cyclodextrin (HPCD) and methyl-beta-cyclodextrin (MCD) solutions were used for soil flushing in column test to evaluate some influent parameters that can significantly increase the removal efficiency. The process parameters chosen were CD concentration, ratio of washing solution volume to soil weight, and temperature of washing solution. These parameters were found to have a significant and almost linear effect on PAH removal from the contaminated soil, except the temperature where no significant enhancement in PAH extraction was observed for temperature range from 5 to 35 degrees C. The PAHs extraction enhancement factor compared to water was about 200.     

Polycyclic aromatic hydrocarbon removal from water by natural fiber sorption.

The use of two natural sorbents, kapok and cattail fibers, were investigated for polycyclic aromatic hydrocarbon (PAH) removal from water. Naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, and fluoranthene were the PAHs studied. For comparative purposes, a commercial polyester fiber sorbent was included in the investigation. The PAH sorption and retention capabilities of the three fibers were determined through batch and continuous-flow experiments under non-competitive and competitive conditions. In the batch experiments, cattail fiber was the most effective sorbent. Kapok fiber provided the lowest PAH retention, while cattail fiber had slightly less PAH retention than polyester fiber. When two PAHs were present in the same system, a competitive effect on the much less hydrophobic PAH was observed. Similar results were obtained in the column experiments, except that polyester fiber performed much poorer on naphthalene. Cattail fiber is a promising sorbent for treating PAH-contaminated water, such as urban runoff.     

The control of mercury vapor using biotrickling filters

The feasibility of using biotrickling filters for the removal of mercury vapor from simulated flue gases was evaluated. The experiments were carried out in laboratory-scale biotrickling filters with various mixed cultures naturally attached on a polyurethane foam packing. Sulfur oxidizing bacteria, toluene degraders and denitrifiers were used and compared for their ability to remove Hg 0 vapor. In particular, the biotrickling filters with sulfur oxidizing bacteria were able to remove 100% of mercury vapor, with an inlet concentration of 300-650 microg m(-3), at a gas contact time as low as six seconds. 87-92% of the removed mercury was fixed in or onto the microbial cells while the remaining left the system with the trickling liquid. The removal of mercury vapors in a biotrickling filter with dead cells was almost equivalent to this in biotrickling filters with live cells, indicating that significant abiotic removal mechanisms existed. Sulfur oxidizing bacteria biotrickling filters were the most effective in controlling mercury vapors, suggesting that sulfur played a key role. Identification of the location of metal deposition and of the form of metal was conducted using TEM, energy dispersive X-ray analysis (EDAX) and mercury elution analyses. The results suggested that mercury removal was through a series of complex mechanisms, probably both biotic and abiotic, including sorption in and onto cellular material and possible biotransformations. Overall, the study demonstrates that biotrickling filters appear to be a promising alternative for mercury vapor removal from flue gases.     

Effect of VOC loading on the ozone removal efficiency of activated carbon filters

Activated carbon (AC) filters are used widely in air cleaning to remove volatile organic compounds (VOCs) and ozone (O(3)). This paper investigates the O(3) removal efficiency of AC filters after previous exposure to VOCs. Filter performance was tested using coconut shell AC and two common indoor VOCs, toluene and d-limonene, representing low and high reactivities with O(3). AC dosed with low, medium and high loadings (28-100% of capacity) of VOCs were exposed to humidified and ozonated air. O(3) breakthrough curves were measured, from which O(3) removal capacity and parameters of the Elovich chemisorption equation were determined. VOC-loaded filters were less efficient at removing O(3) and had different breakthrough behavior than unloaded filters. After 80 h of exposure, VOC-loaded AC samples exhibited 75-95% of the O(3) removal capacity of unloaded samples. O(3) breakthrough and removal capacity were not strongly influenced by the VOC-loading rate. Toluene-loaded filters showed rapid O(3) breakthrough due to poisoning of the AC, while pseudo-poisoning (initially higher O(3) adsorption rates that rapidly decrease) is suggested for limonene-loaded filters. Overall, VOC loadings provide an overall reduction in chemisorption rates, a modest reduction in O(3) removal capacity, and sometimes dramatic changes in breakthrough behavior, important considerations in filter applications in environments where both O(3) and VOCs are present.     

Determination of total and available fractions of PAHs by SPME in oily wastewaters: overcoming interference from NAPL and NOM

Background, aim, and scope  

Polycyclic aromatic hydrocarbons (PAHs) are often found in oily wastewaters. Their presence is usually the result of human activities and has a negative effect on the environment. One important step in addressing this problem is to evaluate the effectiveness of PAH removal by biological processes since these are the most cost-effective treatments known today. Many techniques are presently available for PAH determination in wastewaters. Solid phase microextracion (SPME) is known to be one of the most effective techniques for this purpose. When analyzing complex matrices with substances such as natural organic matter (NOM) and non-aqueous phase liquids (NAPL), it is important to differentiate the free dissolved PAH from matrix-bonded PAH. PAHs associated with the bonded fraction are less susceptible to biological treatment. The present study concerns the development of a simple and suitable methodology for the determination of the freely dissolved and the total fraction of PAHs present in oily wastewaters. The methodology was then applied to an oily wastewater from a fuel station retention basin.     

煤矸石堆积下多环芳烃的淋溶污染特征

淋溶是使有害物质析出的主要途径之一。为查明煤矸石堆放淋溶造成的有机污染效应,对不同风化强度煤矸石进行了动态淋溶模拟实验,系统研究了煤矸石中US EPA优先控制的16种多环芳烃（PAH16）的析出规律和迁移方式。获得煤矸石中多环芳烃（PAHs）淋溶特征如下：煤矸石堆积期遭受短期降雨（500~1 600 mm）作用后,煤矸石溶出的PAH16总质量浓度达125.6~451.2 ng/L。PAH16溶出量初期较高,在一定降雨期后又达到峰值,酸雨条件下,煤矸石山淋溶出的PAH16可由线性累加转为指数快速累加的趋势。淋溶液中优势组分为萘、二氢苊、芴和菲,4种组分之和占所测PAHs总量的80%~90%。煤矸石溶出的PAHs环数分布为2环〉3环〉4环〉5环、6环。迁移方式上,2环PAHs多以溶解相迁移,3环PAHs主要以颗粒态迁移,存在少量溶解形式,而4环以上PAHs则以颗粒相形式迁移。     

Chlorobenzenes removal from municipal solid waste incineration fly ash by surfactant-assisted column flotation

The organic contaminants in municipal solid waste incineration (MSWI) fly ash, including chlorinated aromatic compounds and polycyclic aromatic hydrocarbons, have high toxicity and a potential negative impact on the environment. An effective and low energy consumption technique to remove the organic contaminants from MSWI fly ash is required urgently. Organic contaminants, such as chlorobenzenes (CBzs), in MSWI fly ash are known to become enriched in the unburnt carbon (UC) fraction. It is proposed that removal of UC from fly ash will result in the effective removal of most organic micropollutants. In this research, we use a technique of surfactant-assisted column flotation to decontaminate MSWI fly ash by removal of the CBzs-enriched UC from MSWI fly ash. We find that 39.8% of CBzs can be removed from fresh MSWI fly ash with 61.7% UC removal efficiency, whereas only 33.2% of CBzs can be removed from weathered MSWI fly ash with a low UC removal efficiency of 33.7%. By adding a mixture of two kinds of surfactants: sorbitan mono-oleate and polyoxyethylene (20) sorbitan mono-oleate to the weathered fly ash, 47.0% of CBzs were removed at the hydrophile lipophile balance value of 13.5, while the UC removal efficiency increased to 49.0%. The results show that surfactants can enhance CBzs and UC removal efficiencies during the column flotation process. Higher CBzs and UC removal efficiencies can be expected by further optimizing the conditions of surfactant-assisted column flotation.     

Atmospheric Polycyclic Aromatic Hydrocarbons at a Point Source of Emissions. Part A: Identification and Determination of Polycyclic Aromatic Compounds in Airborne Particulate Matter Near a Horizontal Stud Soderberg Plant

Abstract

This paper summarizes the sampling and analytical methods developed to identify and measure polycyclic aromatic hydrocarbons (PAH) and related aromatic compounds near a Horizontal Stud Soderberg plant at Jonquiere, Quebec, Canada. The primary source of PAH is the coal tar pitch used as a binder in Soderberg anodes. Twice a week at a number of sampling sites, airborne particulate matter was collected on glass-fiber filters using a Hi-Vol sampler for a twenty-four hour period. Organics on the filter were Soxhlet extracted with benzene.

Identification was done by gas chromatography-mass spectrometry (GC-MS). The vast majority of compounds present were PAH, but small amounts of alkyl PAH and polycyclic aromatic compounds with heteroatoms such as nitrogen, oxygen and sulfur were also identified. Based on the GC-MS identification, a group of 14 PAH was selected for monitoring. Frequent PAH determinations revealed that the ratio of Benzo(a- )Pyrene to total PAH on the Hi-Vol filters is relatively constant in ambient air from one sampling station to another.     

Removal of two cationic dyes from a textile effluent by filtration-adsorption on wood sawdust

BACKGROUND: Wastewater from textile industry contains various contaminants such as dyes, surfactants and heavy metals. Textile dyes have synthetic origin and complex aromatic molecular structures that make them difficult to biodegrade when discharged in the ecosystem. The objective of this study was to examine the decolourisation of textile effluents containing cationic dyes by filtration-adsorption on wood sawdust from two different origins; fir as an example of a conifer tree, and beech as an example of a deciduous one, and to explain the adsorption mechanism. METHODS: The process of dye removal was applied to a synthetic effluent in batch mode. Adsorption experiments were performed by suspending sawdust in the effluent and analyzing the supernatant by spectrophotometry. The effectiveness of the treatment process was evaluated by measuring coloration. RESULTS AND DISCUSSION: Experimental results showed a significant potential for wood sawdust, especially coniferous sawdust, to remove cationic dyes from textile effluents. Adsorption kinetics was influenced by the initial dye concentration, nature and amount of sorbent as well as sorbent particle size. The adsorption followed a pseudo first-order kinetics. For both basic dyes, the Langmuir adsorption equation showed a better fit than the Freundlich equation. CONCLUSION: Filtration-adsorption using an inexpensive and readily available biosorbent provided an attractive alternative treatment for dye removal, and it does not generate any secondary pollution. Recommendations and Perspectives. Laboratory studies provide promising perspectives for the utilization of wood sawdust as renewable adsorbent for reducing pollution while enhancing the reuse of textile effluents. However, the treatment process needs to be applied to the other textile dye classes in order to be used on an industrial scale.     

粉煤灰合成沸石去除城市暴雨径流中氨氮

采用粉煤灰为原料,通过耦合碱熔-两步合成法制得3种合成沸石产品,并以合成沸石制备大粒径的功能填料。通过氨氮吸附速率实验和等温吸附实验探讨了合成沸石及功能填料的氨氮吸附速率和最大吸附容量(Qm),以功能填料构建模拟人工快速渗滤系统,研究其对城市暴雨径流中氨氮的去除效果。结果表明,合成沸石对氨氮的吸附速率极快,5min去除率约达到75%,氨氮最大吸附容量为11.36～16.13 mg/g;功能填料对氨氮的最大吸附容量有所下降,但氨氮吸附速率仍较快,应用于模拟人工快速渗滤系统时能在较高的水力负荷下快速去除城市暴雨径流中的氨氮。碱处理再生法更适于进行合成沸石功能填料原位再生,氨氮吸附容量一次再生率达到67%～87%。     

Demonstration of Microfiltration Technology

The U.S. Environmental Protection Agency (EPA), in cooperation with E.I. DuPont de Nemours & Company, Inc. (DuPont) and the Oberlin Filter Company (Oberlin), undertook a field demonstration project to evaluate microfiltration technology for removal of zinc and suspended solids from wastewater. The microfiltration system utilized DuPont's Tyvek T-980 membrane filter media in conjunction with the Oberlin automatic pressure filter. The project was undertaken at the Palmerton Zinc Superfund site in April 1990 to verify the ability of the technology to remove dissolved zinc from the site's shallow groundwater. Pretreatment of the groundwater with lime for pH adjustment to precipitate dissolved zinc and other metals was included as part of the technology demonstration program. Analysis of the treated filtrate indicated that the system removed precipitated zinc and other suspended solids at an efficiency greater than 99.9 percent. The filter cake produced during the study passed both the Extraction Procedure (EP) Toxicity and the Toxicity Characteristic Leaching Procedure (TCLP) tests.     

Direct analysis of polycyclic aromatic hydrocarbons in cloud-water aerosol filtrates using laser desorption mass spectrometry

A novel technique for the rapid screening of polyaromatic hydrocarbons (PAHs) in atmospheric particulates is presented. Two-step laser desorption laser photoionisation time-of-flight mass spectrometry was used to assay for PAHs in cloud-water particulates collected near Peebles in southern Scotland. The particulates were examined in situ on their host filters removing the requirement for time-consuming sample extraction and separation. The mass spectra obtained from a single filter are shown. The principal components of these are assigned to PAH contaminants and phthalate contaminants. A distribution of PAHs was observed using 193 nm laser photoionisation. The mass spectrum obtained on using 248 nm laser photoionisation exhibits a different intensity distribution demonstrating an ionisation wavelength dependence. The utility of the technique for rapid screening of PAHs and other polyaromatic species is discussed.