An evaluation of reactive filter media for treating landfill leachate

A laboratory bench-scale column study was conducted to evaluate permeable reactive filter materials as a new method for removal of heavy metals and inorganic nitrogen from landfill leachate. Mixtures of sand and peat, blast-furnace slag (BFS) and peat, and Polonite and peat were tested by loading columns with leachate collected from a pond at Tvetaverket Landfill, Sweden. Sand, peat and Polonite represent natural materials. BFS is a by-product from steel-works. The metal treatment efficiencies of the media were assessed and Polonite was found to perform best, where Mn, Fe, Zn and Cu concentrations were removed by 99%, 93%, 86% and 67%, respectively. This material was also able to reduce inorganic N by 18%. The BFS showed good removal efficiency for Cu (66%), Zn (62%), Ni (19%) and Mo (16%). The sand-peat mixture did not demonstrate a promising removal capacity for any of the elements studied with the exception of Cu (25%). The removal of different elements was suggested to be a combination of several factors, i.e. precipitation, ion exchange and adsorption. Prior to full-scale application of reactive filters at a landfill site, matrix selection, filter design and operational procedures must be developed.     

一种废气吸收新装置的传质试验

介绍了一种废气吸收装置的传质试验,该装置利用射流泵进行吸气和液气混合。在分析了喷射形式下传质吸收研究的资料后,对该装置进行了模拟废气吸收试验,结合泵的性能研究装置的传质吸收特性,对不同面积比射流泵的传质情况进行了分析。     

A study of the errors in x-ray quantitative analysis procedures for aerosols collected on filter media

A large number of experimental variables are utilized in the X-ray quantitative analysis of crystalline and amorphous components of aerosols collected by air filtration methods. The individual errors associated with these variables can be combined statistically through use of an error expression applied to the basic analytical equations providing that either measurements of standard deviations or their estimates can be obtained. This procedure has been developed for the variables of X-ray mass absorption, aerosol load density, transmission and diffraction intensities, and reference intensity constants, and has been applied in the quantitative analysis of two filter samples containing both crystalline and amorphous components. The results indicate that, despite some subjectivity in estimating some of the required parameters, reasonable error magnitudes for the component weight fractions are obtained.By being consistent in the way one obtains the initial standard deviations for the input data, one may determine which of the variables most seriously affects the accuracy of the determined weight fractions. For the samples studied here, a marked sensitivity of the resulting weight fractions to reference intensity constants and aerosol load density is revealed.     

Evaluation of thermal optical analysis method of elemental carbon for marine fuel exhaust

The awareness of black carbon (BC) as the second largest anthropogenic contributor in global warming and an ice melting enhancer has increased. Due to prospected increase in shipping especially in the Arctic reliability of BC emissions and their invented amounts from ships is gaining more attention. The International Maritime Organization (IMO) is actively working toward estimation of quantities and effects of BC especially in the Arctic. IMO has launched work toward constituting a definition for BC and agreeing appropriate methods for its determination from shipping emission sources. In our study we evaluated the suitability of elemental carbon (EC) analysis by a thermal-optical transmittance (TOT) method to marine exhausts and possible measures to overcome the analysis interferences related to the chemically complex emissions. The measures included drying with CaSO_4, evaporation at 40–180ºC, H₂O treatment, and variation of the sampling method (in-stack and diluted) and its parameters (e.g., dilution ratio, Dr). A reevaluation of the nominal organic carbon (OC)/EC split point was made. Measurement of residual carbon after solvent extraction (TC-C_SOF) was used as a reference, and later also filter smoke number (FSN) measurement, which is dealt with in a forthcoming paper by the authors. Exhaust sources used for collecting the particle sample were mainly four-stroke marine engines operated with variable loads and marine fuels ranging from light to heavy fuel oils (LFO and HFO) with a sulfur content range of <0.1–2.4% S. The results were found to be dependent on many factors, namely, sampling, preparation and analysis method, and fuel quality. It was found that the condensed H₂SO₄ + H₂O on the particulate matter (PM) filter had an effect on the measured EC content, and also promoted the formation of pyrolytic carbon (PyC) from OC, affecting the accuracy of EC determination. Thus, uncertainty remained regarding the EC results from HFO fuels.

Implications: The work supports one part of the decision making in black carbon (BC) determination methodology. If regulations regarding BC emissions from marine engines will be implemented in the future, a well-defined and at best unequivocal method of BC determination is required for coherent and comparable emission inventories and estimating BC effects. As the aerosol from marine emission sources may be very heterogeneous and low in BC, special attention to the effects of sampling conditions and sample pretreatments on the validity of the results was paid in developing the thermal-optical analysis methodology (TOT).     

中置生物活性炭滤池的选炭

实验通过对传统臭氧-生物活性炭工艺的调整,采用臭氧-曝气生物活性炭滤池-砂滤池工艺,对比研究了4mm柱状炭、4 mm破碎炭和1.5 mm柱状炭3种不同类型活性炭用于给水深度处理的运行效果。结果表明,粒径为1.5 mm的柱状炭对有机物和氨氮的去除效果以及出水浊度方面优于其他2种活性炭,但炭滤池水头损失偏大,且不够稳定,适当增加柱状炭的粒径可稳定和降低滤池的水头损失。     

An evaluation of the protein mass of particulate matter

This research study provides the characterization of mass percent of protein-based particulate matter in total ambient particulate matter collected in a metropolitan area of NC. The project determined the percentages of protein-based ambient bioaerosols for particles in the 2.5–10 μm range and for particles in the range of 2.5 μm or less in 298 samples taken over a six-month period. The analysis of total protein mass was used as an all-inclusive indicator of biologically based aerosols. These organic bioaerosols may have nucleated with inorganic non-biological aerosols, or they may be combined with inert aerosols. The source of these bioaerosols may be any combination of pollen, mold, bacteria, insect debris, fecal matter, or dander, and they may induce irritational, allergic, infectious, and chemical responses in exposed individuals. Ambient samples of PM_2.5 and PM_10−2.5 were analyzed for gravimetric mass and total protein mass. The results for 19 of 24 sample periods indicated that between 1% and 4% of PM_10−2.5 and between 1% and 2% of PM_2.5 mass concentrations were made of ambient protein bioaerosols. (The remaining 5 of 24 sample periods yielded protein results which were below detectable limits.)     

Development of an improved optical transmission technique for black carbon (BC) analysis

A new optical transmission technique for black carbon (BC) analysis was developed to minimize interferences due to scattering effects in filter samples. A standard thermal analysis method (VDI, 1999) is used to link light attenuation by the filter samples to elemental carbon (EC) concentration. Scattering effects are minimized by immersion of the filters in oil of a similar refractive index, as is often done for microscopy purposes. Light attenuation was measured using both a white light source and a red LED of 650 nm. The usual increase in overestimation of BC concentrations with decreasing BC amount in filter samples was found considerably reduced. Some effects of BC properties (e.g. fractal dimension, microstructure and size distribution) on the specific attenuation coefficient B_ATN, however, are still present for the treated samples. B_ATN was found close to 1 m² g⁻¹ for dry-dispersed industrial BC and 7 m² g⁻¹ for nebulized BC. Good agreement was found between the oil immersion, integrating sphere and a polar photometer technique and Mie calculations. The average specific attenuation coefficient of ambient samples in oil varied between 7 and 11 m² g⁻¹ for white light and 6 and 9 m² g⁻¹ for red light (LED). B_ATN was found to have much less site variation for the treated than for the untreated samples. The oil immersion technique improved also the correlation with thermally analyzed EC. This new immersion technique therefore presents a considerable improvement over conventional optical transmission techniques and may therefore serve as a simple, fast and cost-effective alternative to thermal methods.     

滤布滤池强化处理城市二级出水中试研究

采用滤布滤池对南方某城市污水处理厂二级出水进行强化处理中试研究,以达到中水回用的目的。实验选用氯化铁(FeCl₃)、聚合氯化铝铁（PAFC）和聚合氯化铝（PAC）作为强化滤布滤池除磷效果的混凝剂。当不投加混凝剂时,滤布滤池对TP和COD的平均去除率为28.76%和8%,其中TP的去除效果受进水水质影响较大;当投加氯化铁、聚合氯化铝铁与聚合氯化铝强化滤布滤池时,滤布滤池对TP的平均去除率分别为63.58%、60.13%和66.94%,TP去除效果受进水水质影响较小;对SS的平均去除率分别为70.7%、64.3%和49.1%;对COD平均去除率分别为17.7%、26.3%和27.7%。滤布滤池对TN和NH₃-N去除效果不稳定。     

Feasibility of coupling a thermal/optical carbon analyzer to a quadrupole mass spectrometer for enhanced PM2.5 speciation

A thermal/optical carbon analyzer (TOA), normally used for quantification of organic carbon (OC) and elemental carbon (EC) in PM_2.5 (fine particulate matter) speciation networks, was adapted to direct thermally evolved gases to an electron impact quadrupole mass spectrometer (QMS), creating a TOA-QMS. This approach produces spectra similar to those obtained by the Aerodyne aerosol mass spectrometer (AMS), but the ratios of the mass to charge (m/z) signals differ and must be remeasured using laboratory-generated standards. Linear relationships are found between TOA-QMS signals and ammonium (NH₄⁺), nitrate (NO₃^?), and sulfate (SO₄^2-) standards. For ambient samples, however, positive deviations are found for SO₄^2-, compensated by negative deviations for NO₃^?, at higher concentrations. This indicates the utility of mixed-compound standards for calibration or separate calibration curves for low and high ion concentrations. The sum of the QMS signals across all m/z after removal of the NH₄⁺, NO₃^?, and SO₄^2- signals was highly correlated with the carbon content of oxalic acid (C?H?O?) standards. For ambient samples, the OC derived from the TOA-QMS method was the same as the OC derived from the standard IMPROVE_A TOA method. This method has the potential to reduce complexity and costs for speciation networks, especially for highly polluted urban areas such as those in Asia and Africa.

Implications: Ammonium, nitrate, and sulfate can be quantified by the same thermal evolution analysis applied to organic and elemental carbon. This holds the potential to replace multiple parallel filter samples and separate laboratory analyses with a single filter and a single analysis to account for a large portion of the PM_2.5 mass concentration.     

Effects of post-sampling conditions on ambient carbon aerosol filter measurements

Ambient carbonaceous material collected on quartz filters is prone to measurement artifacts due to material gained or lost during post-sampling field latency, shipping, and storage. In seventeen sampling events over a one year period, ambient PM_2.5 aerosols were collected on quartz filters (without denuders) and subjected to various filter treatments to assess the potential for and extent of artifacts. The filter treatments simulated post-sampling environments that filters may be exposed to and included: storage at 40 °C for up to 96 h, storage at ?16 °C for 48 h, and storage at room temperature (～21 °C) for 48 h. Carbon mass on the filters was measured using a thermal-optical method. The total carbon (TC), total organic carbon (TOC) and total elemental carbon (TEC) as well as carbon thermal fraction masses were obtained. Statistical analyses were performed to identify significant differences in carbon fraction concentrations between filters analyzed immediately after sampling and after being subjected to treatment.TOC and TC concentrations decreased by on average 15 ± 5% and 10 ± 4%, respectively, for filters maintained at 40 °C for 96 h but did not change for filters stored at room temperature or frozen for 48 h. TEC did not change for any of the filter treatments. The mass concentration for the organic carbon thermal fraction that evolves at the lowest temperature step (OC1) decreased with increasing storage time at 40 °C with average losses of 70 ± 7% after 96 h. Therefore, OC1 is not a stable measurement due to post-sampling conditions that may be encountered. This work demonstrates that TOC and TC can have substantial measurement artifacts on filters subjected to field latency and other non-temperature controlled post-sampling handling, compared to the carbon loadings on the filter at the end of the sampling period.     

Preparation of electrospun polyurethane filter media and their collection mechanisms for ultrafine particles

Electrospinning is a simple and versatile process to produce polymer nanofibers, which are useful for ultrafine particle filtration. In this study, a polyurethane filter with an average fiber diameter of 150–250 nm was prepared through the electrospinning process and its filtration characteristics were investigated. We found that the electrospun fiber diameter was highly dependent on the polyurethane concentration, electric field, and tip-to-collector distance. As the polyurethane concentration, electric field, and tip-to-collector distance under the same electric field increased, the fiber diameter increased. We also found that the produced filter media had a minimum collection efficiency at particles sizes from 80 to 100 nm, which implies an electrostatic attraction between the filter and the test particles. Furthermore, we observed that interception was a predominant collection mechanism at Peclet numbers higher than 10 in nanofiber filtration for ultrafine particles.

Implications:

A polyurethane nanofiber filter with excellent mechanical properties was prepared, and the effect of operating conditions on fiber morphology was examined. The filter fabricated by an electrospinning process is charged and has high filtration efficiency due to electrostatic force. Therefore, it can be a good alternative to control hazardous ultrafine particles.     

填料在净化污水过程中渗透性能变化趋势的研究

选取腐殖垃圾和砂以及两者质量比分别为4:1、3:2、2:3的混合物共5种填料,在1.0 m/d的水力负荷下,进行人工快速渗滤系统净化生活污水的试验,研究填料在进水过程中渗透性能的变化趋势.结果表明,腐殖垃圾的初始饱和水力渗透系数(K)最大,为3.32×10-2cm/s,而砂的初始K只有5.14×10-3cm/s,腐殖垃圾含量越大的混合物其仞始K也越大.在净化污水的过程中,5种填料的K逐渐减小,腐殖垃圾含量越大的混合物其K降幅也越大.随着进水时间的延长,各个填料柱填料层50～250 mm处的水头损失占总水头损失(填料层50～450mm处)的比例均逐渐增加,最终各个填料柱均发生堵塞,堵塞均发生在填料层50mm以上范围内.     

The IMPROVE_A temperature protocol for thermal/optical carbon analysis: maintaining consistency with a long-term database

Thermally derived carbon fractions including organic carbon (OC) and elemental carbon (EC) have been reported for the U.S. Interagency Monitoring of PROtected Visual Environments (IMPROVE) network since 1987 and have been found useful in source apportionment studies and to evaluate quartz-fiber filter adsorption of organic vapors. The IMPROVE_A temperature protocol defines temperature plateaus for thermally derived carbon fractions of 140 degrees C for OC1, 280 degrees C for OC2, 480 degrees C for OC3, and 580 degrees C for OC4 in a helium (He) carrier gas and 580 degrees C for EC1, 740 degrees C for EC2, and 840 degrees C for EC3 in a 98% He/2% oxygen (O2) carrier gas. These temperatures differ from those used previously because new hardware used for the IMPROVE thermal/optical reflectance (IMPROVE_TOR) protocol better represents the sample temperature than did the old hardware. A newly developed temperature calibration method demonstrates that these temperatures better represent sample temperatures in the older units used to quantify IMPROVE carbon fractions from 1987 through 2004. Only the thermal fractions are affected by changes in temperature. The OC and EC by TOR are insensitive to the change in temperature protocol, and therefore the long-term consistency of the IMPROVE database is conserved. A method to detect small quantities of O2 in the pure He carrier gas shows that O2 levels above 100 ppmv also affect the comparability of thermal carbon fractions but have little effect on the IMPROVE_TOR split between OC and EC.     

Evaluation of an activated carbon filter for the retention of selected pesticide vapours

Abstract

An activated charcoal bed unit (ACBU) was constructed using teflon stock. The unit duplicated the flow and bed design of a commercially available tractor mounted filter for removing pesticides from the air.

Eight pesticides (4 herbicides and 4 insecticides) were used to test the retention efficiency of ACBU over a 12–48 h period with the ACBU in place. Polyurethane foam (PUF) plugs in series trapped any residual pesticide that came through the ACBU.

The ACBU retained 93–100% of the pesticides tested. The unit thus provides an efficient mechanism for removing airborne pesticides.     

Evaluation of alternative filter media for particulate matter emission testing of residential wood heating devices

The performance of Teflon-coated glass fiber filter media (Pallflex Emfab TX40) is evaluated for particulate matter (PM) sampling of residential wood heating devices in a dilution tunnel. Thirty samples of varying duration and PM loading and concentration were collected from an U.S. Environmental Protection Agency (EPA) Method 28 dilution tunnel using dual Method 5G sample trains with untreated glass fiber and Emfab filters. Filters were weighed soon after the end of sampling and again the next day after equilibration at 35% relative humidity (RH). PM concentrations from both types of filters agreed very well with 1-day equilibration, demonstrating that Emfab filters are appropriate for use in measuring PM from residential wood burning appliances in a dilution tunnel and have performance equal to or better than the glass fiber filter media. Agreement between filter media without equilibration was erratic, with PM from glass fiber filter samples varying from slightly less than the Emfab samples to as much as 2.8 times higher. Some of the glass fiber filters lost substantial mass with equilibration, with the highest percent loss at lower filter mass loadings. Mass loss for Emfab samples was a small percentage of the mass and very consistent across the range of mass loadings. Taken together, these results may indicate water uptake on the glass fiber media that is readily removed with 1-day equilibration at moderate RH conditions.

Implications: EPA regulations now allow the use of either glass fiber or Teflon filter media for wood appliance PM emission testing. Teflon filter media minimizes the potential for acid-gas PM artifacts on glass fiber filters; this is important as EPA moves toward the use of locally sourced cordwood for testing that may have higher sulfur content. This work demonstrates that the use of Teflon-coated glass fiber filters can give similar PM measurement results to glass fiber filters after 1 day of equilibration. With no equilibration, measured PM from glass fiber filters was usually higher than from Teflon-coated glass fiber filters.     

An evaluation of measurement methods for organic, elemental and black carbon in ambient air monitoring sites

The carbonaceous components of Particulate Matter samples form a substantial fraction of their total mass, but their quantification depends strongly on the instruments and methods used. United Kingdom monitoring networks have provided many relevant data sets that are already in the public domain. Specifically, hourly organic carbon (OC) and elemental carbon (EC) were determined at four sites between 2003 and 2007 using Rupprecht and Pattashnik (R & P) 5400 automatic instruments. Since 2007, daily OC/EC measurements have been made by manual thermo-optical analysis of filter samples using a Sunset Laboratory Carbon Aerosol Analysis instrument. In parallel, long term daily measurements of Black Smoke, a quantity directly linked to black carbon (measured by aethalometers) and indirectly related to elemental carbon, have been made at many sites. The measurement issues associated with these techniques are evaluated in the context of UK measurements, making use of several sets of parallel data, with the aim of aiding the interpretation of network results. From the results available, the main conclusions are that the R & P 5400 instruments greatly under-read EC and total carbon (TC = OC + EC) at kerbside sites, probably due to the fact that the smaller particles are not sampled by the instrument; the R & P 5400 instrument is inherently difficult to characterise, so that all quantitative results need to be treated with caution; both aethalometer and Black Smoke (converted to black carbon) measurements can show reasonable agreement with elemental carbon results; and manual thermo-optical OC/EC results may under-read EC (and hence over-read OC), whether either transmittance or reflectance is used for the pyrolysis correction, and this effect is significant at rural sites.     

不同滤料及挂膜方式对养殖污水处理效果的研究

实验研究了填装不同滤料的4种生物滤池在3种挂膜方式下生物功能启动的情况。结果表明,相同挂膜方式下不同生物滤池中,氨氮浓度都随着系统运行时间的延长而逐渐下降,亚硝态氮浓度先上升达到峰值后下降,但悬浮球形滤料处理污水的效果明显优于其他滤料。悬浮球形滤料下不同挂膜方式,系统稳定时间不同,自然挂膜、活性污泥挂膜、优势菌挂膜三者依次约为39、30和21 d,但采用优势菌挂膜由于生物膜容易脱落,氨氮的处理效果较差。采用活性污泥法加入悬浮球形生物滤料是处理养殖污水行之有效的方法。系统运行27 d可使氨氮的浓度降低到0.033 mg/L,系统运行33 d,亚硝态氮浓度可下降到0.045 mg/L左右。     

不同填料组合的曝气生物滤池前置反硝化工艺特性的比较研究

研究了2组不同填料组合的前置反硝化曝气生物滤池（BAF）脱氮工艺：陶粒 沸石工艺（C-Z BAF）和沸石 陶粒工艺（Z-C BAF）,比较二者在不同的水力停留时间（HRT）、气水比和回流比条件下的工艺特性。当进水COD、氨氮和TN容积负荷分别为0.72～5.97、0.09～0.60和0.11～0.78 kg/（m3·d）时,C-Z BAF和Z-C BAF的最佳HRT、气水比和回流比分别为1.5 h、5∶1、1∶1和1.5 h、5∶1、2∶1,相应COD、氨氮和TN的平均去除率分别为94.7%、99.0%、62.2%和93.2%、99.5%、70.1%。单因素方差分析结果表明,HRT对2组工艺的各种污染物的去除率均有显著影响;回流比对Z-C BAF的TN去除率存在显著的影响,而对C-Z BAF的TN去除率几乎没有影响。污染物沿程分布分析结果表明,两组工艺的COD去除主要发生在缺氧滤池以及好氧滤池0～0.3 m的填料区;硝化作用主要发生在好氧滤池的0～0.6 m填料区,Z-C BAF工艺的硝化速率高于C-Z BAF工艺。Z-C BAF工艺存在明显的同步硝化反硝化作用,且Z-C BAF工艺的脱氮性能优于C-Z BAF工艺。     

电增强活性炭滤芯吸附去除水中微污染物

选取了10种市售活性炭滤芯并测试其相关理化性质,筛选出比表面积高、导电性好的滤芯用于电增强吸附二氯乙酸(DCAA)、左氧氟沙星(LVFX)和环丙沙星(CIP) 3种典型饮用水中的微污染物。3种污染物的电增强吸附符合二级动力学模型,电增强活性炭滤芯吸附DCAA、LVFX和CIP的最佳初始吸附速率v₀分别达到12.4 mg·(g·h)⁻¹ (2 V)、45.3 mg·(g·h)⁻¹ (−2 V)和93.1 mg·(g·h)⁻¹ (−2 V),相比不加电情况下提高了1.2~1.7倍;3种污染物的电增强吸附等温线符合Langmuir模型,电辅助下DCAA、LVFX和CIP的最大吸附容量q_m可达到26.3 mg·g⁻¹ (2 V)、207.9 mg·g⁻¹ (−2 V)和106.1 mg·g⁻¹ (−2 V),相比于不加电时提升了1.2~3.2倍。在流动态吸附实验中,活性炭滤芯在电增强吸附下的出水的DCAA质量浓度比不加电时更低,出水水质更佳。电增强吸附下的处理水量达到1 300床体积,比不加电条件下提升了2.2倍。以上研究结果表明活性炭滤芯的电增强吸附在饮用水深度处理中有着较好的应用前景。     

Enhancement of organic and nitrogen removal in up-flow floating filter media reactor for piggery wastewater treatment

Integrated up-flow floating media system utilised sponge cube floating bed for microbial attachment and suspended solid clarification. The first reactor was operated under anaerobic condition where high organic removal of more than 85% was reached. It was followed by anoxic/aerobic floating media reactors or chemical coagulation/air stripping units. When biological post treatment was employed, overall organic removal efficiency was up to 98%. In case of chemical post treatment, alum was applied at optimal dose of 1.0 gL⁻¹ with COD, SS and colour removal of 88%, 97% and 93%, respectively. The air stripping process further removed more than 75% of ammonia nitrogen, yielding comparable effluent qualities to the biological process.