活性焦吸附处理一硝基甲苯(MNT)废水

一硝基甲苯(MNT)废水是一种具有高毒性、难降解的火炸药废水。以活性焦为吸附剂,研究了活性焦对MNT废水中COD的吸附性能及pH、时间、温度和活性焦用量对吸附效果的影响,并分析了吸附前后MNT废水水质和急性毒性的变化。实验结果表明,pH、时间和活性焦用量是影响吸附效果的主要因素,吸附过程符合拟二级动力学,吸附速率常数为1.01×10-2g/(mg·min),可以用Freundlich吸附等温线来描述,等温线常数为Kf=1.14×10-4,n=0.58;在pH为3,温度为20℃,活性焦用量为80g/L的条件下吸附MNT废水3 h,COD的去除率达到72.0%,急性毒性下降了98.6%,表明活性焦能有效地吸附处理MNT废水。     

Fate of polycyclic aromatic hydrocarbons during vitrification of incinerator ash in a coke bed furnace

Fate of polycyclic aromatic hydrocarbons (PAHs) during the vitrification of fly ash and bottom ash from the municipal waste incinerator in a coke bed furnace was investigated. In this system, both coke and lime were added to enhance the melting reaction. The major PAH sources in this system were ash and coke, which respectively contributed 97% and 3% of PAHs in the input-mass. During vitrification process, low molecular PAHs (LM-PAH, 2-3-ring), median molecular PAHs (MM-PAH, 4-ring) and high molecular PAHs (HM-PAH, 5-7-ring) mass respectively accounted for >99%, >99% and 84% of the output-mass emitted as the stack flue gas; while those discharged from the slag were <1%, <1% and 16%, respectively. The O/I (output-mass/input-mass) ratio of LM-, MM- and HM-PAHs were 0.063, 0.002 and <0.001, respectively. The high distribution in flue gas and O/I ratio of LM-PAHs is reasonable since they are more easily evaporated, hence difficult to be removed by air pollution control devices. On the contrary, the HM-PAHs, having lower vapor pressure, primarily stays mainly in slag. Based on the 21 total PAH content in feeding ash and slag, the reduction efficiency of the coke bed furnace was >99.9%. To minimize the risk of secondary pollution, the efficiency of coke bed furnace should be improved to reduce the PAH emission into ambient air.     

Air Quality Effects from Quenching Coke with Fresh versus Process Water

Because of the extreme difficulties in sampling the discharge from coke-quench towers, only limited data have been available on the magnitude and effect of the emissions from this source. To evaluate this process better, U.S. Steel retained TRC Environmental Consultants, Inc., to undertake a test program at Gary Works (1) to conduct the necessary sampling tests to develop particulate emission factors for the coke-quenching operation during quenching with fresh water and with waste process water makeup to the quench system and (2) to estimate the impact of the emissions on ambient air quality for both conditions by means of dispersion modeling.

The test results for a new offset quench tower provided with impingement baffles show particulate emissions of 0.35 pound per ton of coal (Ib/ton) for fresh water and 0.45 Ib/ton for process water quenching. The results for an older, straight-through, low-velocity quench tower, also provided with baffles, show 0.32 and 0.64 Ib/ton for fresh and process water quenching, respectively. The results of the dispersion model studies indicate a minimal effect on ambient air concentration of particulates due to coke quenching with either fresh or process water.     

焦炉装煤烟尘治理方案的探讨

焦炉装煤烟尘含有害物质,污染环境,危害人体健康。袋式除尘器的使用,消除了烟尘的污染,但因投资大、运行费用高、操作复杂,难以得到快速、广泛的推广。根据实验结果和已有应用情况,本文推荐了三相流化床除尘装置和颗粒层除尘器,它们可用于焦炉装煤烟尘治理,其投资和运行费用会大大降低。     

焦炉装煤烟尘治理方案的探讨

焦炉装煤烟尘含有害物质，污染环境，危害人体健康。袋式除尘器的使用，消除了烟尘的污染，但因投资大、运行费用高、操作复杂，难以得到快速、广泛的推广。根据实验结果和已有应用情况，本文推荐了三相流化床除尘装置和颗粒层除尘器，它们可用于焦炉装煤烟尘治理，其投资和运行费用会大大降低。     

Fugitive coke oven gas emission profile by continuous line averaged open-path Fourier transform infrared monitoring

Although most coke oven research is focused on the emission of polycyclic aromatic hydrocarbons, well-known carcinogens, little has been done on the emission of volatile organic compounds, some of which are also thought to be hazardous to workers and the environment. To profile coke oven gas (COG) emissions, we set up an open-path Fourier transform infrared (OP-FTIR) system on top of a battery of coke ovens at a steel mill located in Southern Taiwan and monitored average emissions in a coke processing area for 16.5 hr. Nine COGs were identified, including ammonia, CO, methane, ethane, ethylene, acetylene, propylene, cyclohexane, and O-xylene. Time series plots indicated that the type of pollutants differed over time, suggesting that different emission sources (e.g., coke pushing, quench tower, etc.) were involved at different times over the study period. This observation was confirmed by the low cross-correlation coefficients of the COGs. It was also found that, with the help of meteorological analysis, the data collected by the OP-FTIR system could be analyzed effectively to characterize differences in the location of sources. Although the traditional single-point samplings of emissions involves sampling various sources in a coke processing area at several different times and is a credible profiling of emissions, our findings strongly suggest that they are not nearly as efficient or as cost-effective as the continuous line average method used in this study. This method would make it easier and cheaper for engineers and health risk assessors to identify and to control fugitive volatile organic compound emissions and to improve environmental health.     

Use of benzo[a]pyrene relative abundance ratios to assess exposure to polycyclic aromatic hydrocarbons in the ambient atmosphere in the vicinity of a Söderberg aluminum smelter

The purpose of this study was to investigate the use of benzo[a]pyrene (B[a]P) relative abundance ratios (RARs) to assess exposure to polycyclic aromatic hydrocarbons (PAHs) in the urban atmospheric air in the vicinity of a horizontal stud S?derberg aluminum reduction facility. The B[a]P RARs refer to the concentration of individual PAHs measured in a given sample divided by the concentration of B[a]P found in the same sample. This study compared the B[a]P RARs calculated for the facility stack and three sites near the S?derberg aluminum smelter for three different sampling periods. Interperiod differences were significant for many of the PAHs, and the differences between the stations proved insignificant at p < 0.05. The differences between each individual station and the facility stack were significant for all PAHs. B[a]P RARs increased in value at the stations compared with the stack, indicating that B[a]P may be degraded or removed from the atmosphere at a rate greater than that of the majority of the measured PAHs. It is concluded that B[a]P and B[a]P RARs may be poor markers of exposure to PAHs in the vicinity of this S?derberg aluminum refinery for the entire mixture of PAHs present in the ambient atmosphere.     

Use of Benzo[a]pyrene Relative Abundance Ratios to Assess Exposure to Polycyclic Aromatic Hydrocarbons in the Ambient Atmosphere in the Vicinity of a Söderberg Aluminum Smelter

ABSTRACT

The purpose of this study was to investigate the use of benzo[a]pyrene (B[a]P) relative abundance ratios (RARs) to assess exposure to polycyclic aromatic hydrocarbons (PAHs) in the urban atmospheric air in the vicinity of a horizontal stud Söderberg aluminum reduction facility. The B[a]P RARs refer to the concentration of individual PAHs measured in a given sample divided by the concentration of B[a]P found in the same sample. This study compared the B[a]P RARs calculated for the facility stack and three sites near the Söderberg aluminum smelter for three different sampling periods. Interperiod differences were significant for many of the PAHs, and the differences between the stations proved insignificant at p < 0.05. The differences between each individual station and the facility stack were significant for all PAHs. B[a]P RARs increased in value at the stations compared with the stack, indicating that B[a]P may be degraded or removed from the atmosphere at a rate greater than that of the majority of the measured PAHs. It is concluded that B[a]P and B[a]P RARs may be poor markers of exposure to PAHs in the vicinity of this Söderberg aluminum refinery for the entire mixture of PAHs present in the ambient atmosphere.     

Aerial Detection of Vegetation Damage Utilizing a Simple 35-mm Camera System

The body of information presented in this paper is directed to environmental scientists interested in the detection of vegetation damage from air pollution. A dual 35-mm camera bank, manually operated from a small aircraft, was tested as a sensor system for detecting vegetation damage caused by air pollution. The cameras were filled with color and color infrared film and attached to a frame so that simultaneous exposure was possible. This gave a matched pair of photographs for each scene.

A test site was selected that contained three very large coal-fired power plants and a complex of beehive coke ovens. The power plants burn medium-sulfur coal (2 to 3%) which, after coal preparation, results in stack emissions of between 1500 and 2000 ppm sulfur dioxide (S0₂). The coke ovens are relatively old and have effectively no pollution controls. The ovens emit hydrogen sulfide, sulfur dioxide, a variety of benzene-based organics, and heavily dust-laden smoke. The areas near the power plants and coke ovens were monitored by photographic overflights on a regular basis. A variety of aerial photographs were made to test for optimum light conditions, exposure times, and altitudes. Field trips were carried out to examine photographed areas at the ground level.

Two areas were found to have vegetation damage on a scale that made aerial photographs useful. One area was damaged from effluent from the coke ovens; another area exhibited symptoms characteristic of oxidant-type damage where low sulfur dioxide concentrations may have been a contributing factor. In each case the 35-mm camera system was a success in terms of detecting and recording the stress. The chief advantages of such a technique are ease of operation, flexibility, and economy. Compared with conventional aerial photography, the savings are considerable. The disadvantages are small area coverage per photograph and difficulty in obtaining vertical photographs that would have a uniform scale. However, for this particular project, these were not serious drawbacks.     

褐煤活性炭吸附处理焦化废水

研究褐煤活性炭吸附处理焦化废水的性能,为褐煤活性炭用于废水处理提供理论依据和技术指导。以河南某气化厂的焦化废水为吸附原水,进行褐煤活性炭对酚吸附性能的静态和动态实验。静态实验表明,褐煤活性炭对酚的吸附性能符合弗兰德里希（Freundlich）吸附方程式。在室温条件下,对于150 mL焦化废水,当活性炭的用量为10 g,吸附反应时间为1 h,酚的去除率可达92%以上。动态实验研究表明,当进水酚浓度为3 800 mg/L,吸附1.5 h,活性炭的吸附容量可达21.38 mg/g。水处理的实验研究表明,利用褐煤制备的活性炭,对焦化废水具有良好的处理效果。     

dry coke quenching,air pollution and energy: a status report

Dry quenching of incandescent coke after it has been pushed from the coking ovens is a proved, reliable process that is presently being used in several industrialized countries. Foremost among dry quenching’s advantages are: (1) virtual elimination of air pollutants emitted during quenching; (2) elimination of potential water pollution associated with wet quenching; (3) improvements in the working environment; (4) saving substantial amounts of energy in usable forms; (5) producing more usable coke that is superior to wet-quenched coke. By continuously circulating inert gases through a cooling chamber that contains hot coke, dry quenching recovers waste-heat energy that can be used to produce steam, to produce electricity, to preheat combustion air, to preheat coal, to dry coal, and to preheat feed water supplied to fuel-fired boilers. The pay-out period on the capital investment (approximately $7,100,000) for an installation capable of processing 5500 tons of coke/day is less than four years.     

Pesticide uses and transfers in urbanised catchments

An investigation on herbicide uses in two semi-urban catchments was performed simultaneously with sampling campaigns at six stations inside both watersheds from April to July 1998. Urban uses of herbicides exceeded agricultural uses, and transfer coefficients were also higher in urban areas. Therefore, the most used product in urban areas (diuron) was by far the most contaminating product. Householders accounted for 30% of all uses. The highest measured diuron concentration in water surface was 8.7 microg l(-1) due to its use on impervious surfaces. Compared to EEC standards for drinking water production (0.1 microg l(-1)), it is clear that suburban uses of herbicides may severely endanger drinking water production from river water.     

Water flume study of the enhancement of buoyant rise in pairs of merging plumes

When multiple stacks are grouped or ganged together at a site, the effluent plumes are often observed to merge downwind, forming a single buoyant plume whose rate of rise is enhanced relative to the rise of the plumes individually. The magnitude of this rise enhancement depends on many factors, and the few available models for rise enhancement do not always agree with one another. In the present study the rise behaviour of pairs of merging, buoyant plumes was studied by physical modelling in a water flume at 1:500 scale. The experiments were conducted at several stack separation distances and various exit velocity ratios for stack pairs aligned with, or perpendicular to, the ambient flow. Limited experiments were also done with the stacks aligned at other angles to the flow. The stack releases were made buoyant by heating the source water, and the resulting plumes were measured with an array of sensitive temperature probes. From these measurements it was possible to determine the plume structure and rise rates. For small stack separations when the stacks are aligned with the ambient flow, the experimental results show that the enhanced rise is close to, and sometimes above, the maximum theoretical rise enhancement factor of 2^1/3. For the perpendicular orientation there is little or no rise enhancement. The rise enhancement for other stack orientations is somewhere between these two extremes. A plausible physical explanation for the observed behaviour is given, based on initial momentum shielding and line vortex dynamics in the merging plumes.     

Extreme learning machines: a new approach for modeling dissolved oxygen (DO) concentration with and without water quality variables as predictors

In this paper, several extreme learning machine (ELM) models, including standard extreme learning machine with sigmoid activation function (S-ELM), extreme learning machine with radial basis activation function (R-ELM), online sequential extreme learning machine (OS-ELM), and optimally pruned extreme learning machine (OP-ELM), are newly applied for predicting dissolved oxygen concentration with and without water quality variables as predictors. Firstly, using data from eight United States Geological Survey (USGS) stations located in different rivers basins, USA, the S-ELM, R-ELM, OS-ELM, and OP-ELM were compared against the measured dissolved oxygen (DO) using four water quality variables, water temperature, specific conductance, turbidity, and pH, as predictors. For each station, we used data measured at an hourly time step for a period of 4 years. The dataset was divided into a training set (70%) and a validation set (30%). We selected several combinations of the water quality variables as inputs for each ELM model and six different scenarios were compared. Secondly, an attempt was made to predict DO concentration without water quality variables. To achieve this goal, we used the year numbers, 2008, 2009, etc., month numbers from (1) to (12), day numbers from (1) to (31) and hour numbers from (00:00) to (24:00) as predictors. Thirdly, the best ELM models were trained using validation dataset and tested with the training dataset. The performances of the four ELM models were evaluated using four statistical indices: the coefficient of correlation (R), the Nash-Sutcliffe efficiency (NSE), the root mean squared error (RMSE), and the mean absolute error (MAE). Results obtained from the eight stations indicated that: (i) the best results were obtained by the S-ELM, R-ELM, OS-ELM, and OP-ELM models having four water quality variables as predictors; (ii) out of eight stations, the OP-ELM performed better than the other three ELM models at seven stations while the R-ELM performed the best at one station. The OS-ELM models performed the worst and provided the lowest accuracy; (iii) for predicting DO without water quality variables, the R-ELM performed the best at seven stations followed by the S-ELM in the second place and the OP-ELM performed the worst with low accuracy; (iv) for the final application where training ELM models with validation dataset and testing with training dataset, the OP-ELM provided the best accuracy using water quality variables and the R-ELM performed the best at all eight stations without water quality variables. Fourthly, and finally, we compared the results obtained from different ELM models with those obtained using multiple linear regression (MLR) and multilayer perceptron neural network (MLPNN). Results obtained using MLPNN and MLR models reveal that: (i) using water quality variables as predictors, the MLR performed the worst and provided the lowest accuracy in all stations; (ii) MLPNN was ranked in the second place at two stations, in the third place at four stations, and finally, in the fourth place at two stations, (iii) for predicting DO without water quality variables, MLPNN is ranked in the second place at five stations, and ranked in the third, fourth, and fifth places in the remaining three stations, while MLR was ranked in the last place with very low accuracy at all stations. Overall, the results suggest that the ELM is more effective than the MLPNN and MLR for modelling DO concentration in river ecosystems.     

Impact of emissions from natural gas production facilities on ambient air quality in the Barnett Shale area: A pilot study

Rapid and extensive development of shale gas resources in the Barnett Shale region of Texas in recent years has created concerns about potential environmental impacts on water and air quality. The purpose of this study was to provide a better understanding of the potential contributions of emissions from gas production operations to population exposure to air toxics in the Barnett Shale region. This goal was approached using a combination of chemical characterization of the volatile organic compound (VOC) emissions from active wells, saturation monitoring for gaseous and particulate pollutants in a residential community located near active gas/oil extraction and processing facilities, source apportionment of VOCs measured in the community using the Chemical Mass Balance (CMB) receptor model, and direct measurements of the pollutant gradient downwind of a gas well with high VOC emissions. Overall, the study results indicate that air quality impacts due to individual gas wells and compressor stations are not likely to be discernible beyond a distance of approximately 100 m in the downwind direction. However, source apportionment results indicate a significant contribution to regional VOCs from gas production sources, particularly for lower-molecular-weight alkanes (<C6). Although measured ambient VOC concentrations were well below health-based safe exposure levels, the existence of urban-level mean concentrations of benzene and other mobile source air toxics combined with soot to total carbon ratios that were high for an area with little residential or commercial development may be indicative of the impact of increased heavy-duty vehicle traffic related to gas production

ImplicationsRapid and extensive development of shale gas resources in recent years has created concerns about potential environmental impacts on water and air quality. This study focused on directly measuring the ambient air pollutant levels occurring at residential properties located near natural gas extraction and processing facilities, and estimating the relative contributions from gas production and motor vehicle emissions to ambient VOC concentrations. Although only a small-scale case study, the results may be useful for guidance in planning future ambient air quality studies and human exposure estimates in areas of intensive shale gas production.     

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.     

Summary report of the corech (COGAR) workshop on the evaluation of air pollution episodes and associated control measures

Discussions within COGAR during 1981 indicated that collective information on the types of meteorological conditions when large, single sources like power stations contributed to pollution episodes, the frequency with which they occurred and the implications for intermittent control procedures, was important to all member utilities. This paper summarizes the findings of a working group set up by COGAR to study these problems.The investigation was concerned with SO₂ episodes and how feasible it would be to reduce their intensity by such measures as a substitution of low sulphur fuel or switching generation to areas where the probability of an episode developing is less.There has been a considerable reduction in SO₂ emissions in most urban areas in the last two decades. Nevertheless, in many locations, 24-h air pollution episodes can still be attributed to small or medium-sized emissions from low or medium level stacks, rather than to power stations and other large industrial sources with tall stacks. The worst cases in flat terrain where power stations do contribute for many hours are either stagnant conditions persisting for 24 h or a steady wind blowing consistently from an area containing several power stations. Single stations can present problems when topography interferes with dispersion or the stack height is inadequate for the emissions.Data on the frequency with which episodes occur in a given location and the ability to forecast episode conditions in advance, so that if appropriate, preventative measures may be taken, are the desired objectives. Achievement of these objectives requires a detailed understanding of the role of each type of source in relation to different meteorological situations and the local topography. The end product of such studies should be either;

• 1.(a) the specification of a procedure for implementing intermittent emission control
• 2.(b) a demonstration that intermittent control is not an effective option in the area under study.

In case (a), input data required are

• 1.(i) the vertical structure of the atmosphere
• 2.(ii) ground level concentrations of pollutant plus, in complicated topography
• 3.(iii) the three-dimensional distribution of pollutant.

COGAR is a group set up to coordinate atmospheric research in the electrical supply industry in Europe.     

Seasonal Fluctuation in Heavy Metal Pollution in Iran´s Siahroud River - A Preliminary Study (7 pp)

Background The management of its available water resources has become a key issue for Iran. During the last few decades, the water quality of Siahroud River in the coastal plain of the Caspian Sea in Gilan Province in Northern Iran has significantly degraded. The scarcity of water has been compounded by rapid population growth and increasing pollution from fertilizers, pesticides, and municipal and industrial wastes. One of the sources of this degradation is the movement of heavy metals from the river's watershed into the various water systems supported by the river, including the water system for Rasht City. Methods To study the magnitude of heavy metal pollution in the Siahroud River, seven heavy metals including Zn, Cu, Pb, Cd, Mn, Fe, and Ni were measured in duplicate from replicated water samples collected over five consecutive seasons and analyzed by Atomic Absorption Spectrometry. In situ measurements of pH were taken with the samples and total organic carbon (TOC) was analyzed by IR gas measurement. Results The results demonstrated that four of the seven heavy metals including Pb, Fe, Cd, and Mn exceeded permissible safe levels as established by the United States Environmental Protection Agency. Multivariate factor analysis suggested that industrial land-use was the main contributing factor for the high levels of Fe and Mn in the Siahroud River, whereas, Cd was principly from agricultural activities in the watershed. The data also suggested that pH and TOC had an important role in the behaviour of Pb and Mn, and that the elevated levels of these two heavy metals in Siahroud River was the consequence of other anthropogenic sources. Only negligible levels of Zn, Cu and Ni were detected. Finally, all the sampling stations were subjected to cluster analysis. The results indicated that three different zones could be distinguished according to the levels of pollution. In addition, it was shown that the urban areas did not have a significant impact on the heavy metal pollution in the river. This observation stems from the fact that the data from the sampling stations before and after Rasht City were not significantly different. Recommendation . Preventive measures need to be undertaken in the land-use systems and watersheds of the Siahroud River to reduce the pollution levels of Pb, Cd, Mn and Fe.     

小型焦炉废气和废水处理方法

焦炉装煤和推焦烟气合用 1套收集系统。除尘废水经吸附后用于熄焦 ,熄焦水经吸附后用于湿式除尘 ,实现循环零排放。煤气洗涤水循环为废水中氨氮的处理提供了可行的方法     

A Microscopic Classification of Settled Particulates in the Vicinity of a Found Coke-Making Operation

The purpose of this study was the specific identification of the components of settleable particulate samples collected near a coke-making operation. The identification technique employed is a new application of reflected-light microscopic examination of polished sections of the material. The inherent optical characteristics of the individual particles are utilized to classify them as coal (high?, medium?, and low-volatile), coke (coke balls, pyrolytic carbon, slot-oven coke, and char), fly ash or mineral matter. The application of this method of analysis is unique in that classification of particles is based on these inherent optical properties and not on shape, color, or other subjective criteria. This microscopic classification technique is based on accepted methods and should be generally applicable by petrographers on the basis of the photomicrographs and the detailed procedures which are included. On the basis of the data obtained during a six-month study near a coke-making operation it is concluded that material handling and stockpiling operations are major contributors to settled particulate deposition, while coke oven charging was not a major source. This study has shown that a broad program of engineering control will be required to significantly reduce settled particulate deposition in the immediate vicinity of a coke-making operation.