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1.
The objective of this study was to investigate the feasibility of using a microbial biopolymer produced by Acetobacter xylinum as a carbon source for heterotrophic biological denitrification. The denitrification rate, COD availability and nitrite concentration
were response parameters. Under the experimental conditions, a denitrification rate of about 0.74 kg NO 3
−N/m 3d at 6 h retention time was achieved with microbial cellulose (MC). The reactor effluent contained significantly COD concentrations
(20–86 mg/L) so it was not carbon limited, and was receiving enough carbon to facilitate the denitrification process. The
maximum nitrite concentration in the effluent was found to be 0.4 mg/L. However, decreasing the retention time to 3 h significantly
reduced the efficiency. It can be concluded that the MC is a suitable carbon source for nitrate removal in a heterotrophic
biological denitrification process. 相似文献
2.
The anaerobic digestion performances of kitchen waste (KW) and fruit/vegetable waste (FVW) were investigated for establishing engineering digestion system. The study was conducted from lab-scale to pilot-scale, including batch, single-phase and two-phase experiments. The lab-scale experimental results showed that the ratio of FVW to KW at 5:8 presented higher methane productivity (0.725 L CH 4/g VS), and thereby was recommended. Two-phase digestion appeared to have higher treatment capacity and better buffer ability for high organic loading rate (OLR) (up to 5.0 g (VS) L ?1 d ?1), compared with the low OLR of 3.5 g (VS) L ?1 d ?1 for single-phase system. For two-phase digestion, the pilot-scale system showed similar performances to those of lab-scale one, except slightly lower maximum OLR of 4.5 g (VS) L ?1 d ?1 was allowed. The pilot-scale system proved to be profitable with a net profit of 10.173 $/ton as higher OLR (?3.0 g (VS) L ?1 d ?1) was used. 相似文献
3.
The feasibility of degrading 16 USEPA priority polycyclic aromatic (PAH) hydrocarbons (PAHs) with heat and Fe(II)-EDTA catalyzed
persulfate oxidation was investigated in the laboratory. The experiments were conducted to determine the effects of temperature
(i.e. 20 ∘C, 30 ∘C and 40 ∘ C) and iron-chelate levels (i.e., 250 mg/L-, 375 mg/L- and 500 mg/L-Fe(II)) on the degradation of dissolved PAHs in aqueous
systems, using a series of amber glass jars as the reactors that were placed on a shaker inside an incubator for temperature
control. Each experiment was run in duplicate and had two controls (i.e., no persulfate in systems). Samples were collected
after a reaction period of 144 hrs and measured for PAHs, pH and sodium persulfate levels. The extent of degradation of PAHs
was determined by comparing the data for samples with the controls.
The experimental results showed that persulfate oxidation under each of the tested conditions effectively degraded the 16
target PAHs. All of the targeted PAHs were degraded to below the instrument detection limits (∼4 μ/L) from a range of initial
concentration (i.e., 5 μ/L for benzo(a)pyrene to 57 μ/L for Phenanthrene) within 144 hrs with 5 g/L of sodium persulfate at
20 ∘ C, 30 ∘C and 40 ∘C. The data indicated that the persulfate oxidation was effective in degrading the PAHs and that external heat and iron catalysts
might not be needed for the degradation of PAHs.
The Fe(II)-EDTA catalyzed persulfate also effectively degraded PAHs in the study. In addition, the data on the variation of
persulfate concentrations during the experiments indicated that Fe(II)-EDTA accelerated the consumption of persulfate ions.
The obtained degradation data cannot be used to evaluate the influence of temperature and Fe(II) levels on the PAH degradation
because the PAHs under each of the tested conditions were degraded to below the instrument detection limit within the first
sampling point. However, these experiments have demonstrated the feasibility of degrading PAHs in aqueous systems with persulfate
oxidation. Additional tests are being conducted to evaluate the effectiveness of treating PAHs in soils and obtaining the
rate of degradation of PAHs with persulfate oxidation.
Two sets of laboratory experiments were conducted to evaluate the ability of sodium persulfate in oxidizing real world PAH-contaminated
soils collected from a Superfund site in Connecticut. The first set of soil sample were treated only with persulfate and to
the second batch, mixture of persulfate and Fe(II)-EDTA solutions were added. The results of the second test showed that within
24 hours, 75% to 100% of the initial concentrations of seven PAH compounds detected in the soil samples were degraded by sodium
persulfate mixed with FE(II)-EDTA. 相似文献
4.
A combined process comprised of ex-situ nitrification in an aged refuse bioreactor (designated as A bioreactor) and in-situ denitrification in a fresh refuse bioreactor (designated as F bioreactor) was constructed for investigating N 2O emission during the stabilization of municipal solid waste (MSW). The results showed that N 2O concentration in the F bioreactor varied from undetectable to about 130 ppm, while it was much higher in the A bioreactor with the concentration varying from undetectable to about 900 ppm. The greatly differences of continuous monitoring of N 2O emission after leachate cross recirculation in each period were primarily attributed to the stabilization degree of MSW. Moreover, the variation of N 2O concentration was closely related to the leachate quality in both bioreactors and it was mainly affected by the COD and COD/TN ratio of leachate from the F bioreactor, as well as the DO, ORP, and NO 3?-N of leachate from the A bioreactor. 相似文献
5.
In the present study, we investigated the effects of two bulking materials, Sphagnum peat and pine wood chips, on the early stages of biowaste composting in two pilot-scale processes. Emphasis was placed on studying the formation conditions of malodorous compost gases in the initial phases of the processes. The results showed that gas emission leaving an open windrow and a closed drum composting system contained elevated concentrations of fermentative microbial metabolites when acid Sphagnum peat (pH 3.2) was used as a bulking material. Moreover, the gas emission of the peat amended drum composter contained a high concentration of odour (up to 450,000 ou m ?3 of air). The highest odour values in the outlet gas of peat amended composts coincided with the elevated concentrations of volatile organic compounds such as acetoin and buthanedion. We conclude that the acidifying qualities of composting substrates or bulking material may intensify odour emission from biowaste composts and prolong the early stages of the composting process. 相似文献
6.
Much of the biogeochemical cycling research in catchments in the past 25 years has been driven by acid deposition research funding. This research has focused on vulnerable base-poor systems; catchments on alkaline lithologies have received little attention. In regions of high acid loadings, however, even well-buffered catchments are susceptible to forest decline and episodes of low alkalinity in streamwater. As part of a collaboration between the Czech and U.S. Geological Surveys, we compared biogeochemical patterns in two well-studied, well-buffered catchments: Pluhuv Bor in the western Czech Republic, which has received high loading of atmospheric acidity, and Sleepers River Research Watershed in Vermont, U.S.A., where acid loading has been considerably less. Despite differences in lithology, wetness, forest type, and glacial history, the catchments displayed similar patterns of solute concentrations and flow. At both catchments, base cation and alkalinity diluted with increasing flow, whereas nitrate and dissolved organic carbon increased with increasing flow. Sulfate diluted with increasing flow at Sleepers River, while at Pluhuv Bor the sulfate-flow relation shifted from positive to negative as atmospheric sulfur (S) loadings decreased and soil S pools were depleted during the 1990s. At high flow, alkalinity decreased to near 100 μeq L -1 at Pluhuv Bor compared to 400 μeq L -1 at Sleepers River. Despite the large amounts of S flushed from Pluhuv Bor soils, these alkalinity declines were caused solely by dilution, which was greater at Pluhuv Bor relative to Sleepers River due to greater contributions from shallow flow paths at high flow. Although the historical high S loading at Pluhuv Bor has caused soil acidification and possible forest damage, it has had little effect on the acid/base status of streamwater in this well-buffered catchment. 相似文献
7.
The amounts of harmful gas emissions from the process of composting swine waste were determined using an experimental composting
apparatus. Forced aeration (19.2–96.1 l/m 3/min) was carried out continuously, and exhaust gases were collected and analyzed periodically. With weekly turning and the
addition of a bulking agent in order to decrease the moisture content and increase air permeability, the temperature of most
of the contents rose to 70°C and composting was complete within 3–5 weeks. NH 3, CH 4, and N 2O emissions were high in the early stage of composting. About 10%–25% of the nitrogen in the raw material was lost as NH 3 gas during composting. The emission rate of NH 3 mainly depended on the aeration rate, so that as the aeration rate rose, the level of NH 3 emissions increased. The CH 4 and N 2O emissions could be kept lower with adequate treatment at more than 40 l/m 3/min aeration. N 2O may be mainly the result of the denitrification of NO
x
-N in the additional matured compost used as a composting accelerator.
Received: September 11, 1998 / Accepted: November 8, 1999 相似文献
8.
For an effective decomposition and removal of organic halogenated compounds, a packed-bed non-thermal plasma reactor with
in situ absorption of the resulting halogenated products by alkaline sorbent incorporated was proposed. In the plasma reactor,
α-Al 2O 3 particles of 1 and 3 mm (mean particle diameter) were packed as solid dielectric medium to enhance the plasma power density
in the reactor. Further, alkaline sorbent of Ca(OH) 2 was doped onto the surface of α-Al 2O 3 particles, in order to remove halogenated products by in situ absorption with Ca(OH) 2. A high-voltage and high-frequency pulsed power of −15 to 15 kV and 1 kHz was applied to the wire electrode of the plasma
reactor by means of a DC power source. In the present study, as the sample of an organic halogenated compound that is most
popularly used, we selected dichloromethane (CH 2Cl 2), and 500 ppm of the initial concentration of CH 2Cl 2 was fed into the reactor accompanied by air at a fixed flow rate of 500 × 10 −6 m 3 min −1 at room temperature. As a result, it was recognized that the amount of CH 2Cl 2 decomposed by non-thermal plasma in an α-Al 2O 3 particle bed increased with an increase in plasma input power. The ratio of decomposition of CH 2Cl 2 was almost 100% at 13 kV of electric power and 1 kHz frequency, and CO 2, CH 3Cl, COCl 2, HCl, and Cl 2 were observed as the major reaction products. On the other hand, when CH 2Cl 2 was introduced into the plasma reactor where α-Al 2O 3 particles doped with Ca(OH) 2 were packed, the ratio of decomposition of CH 2Cl 2 became higher, compared to the case that α-Al 2O 3 particles were not doped with Ca(OH) 2. Moreover, there were no halogenated by-product gases detected in the outlet gas from the reactor. As the solid reaction
products, CaClOH and Ca(ClO) 2·4H 2O were detected on Ca(OH) 2 by X-ray diffraction. From these findings, it was recognized that CH 2Cl 2 was decomposed more effectively without producing unwanted harmful halogenated by-products in the proposed non-thermal plasma
reactor where α-Al 2O 3 particles doped with Ca(OH) 2 sorbent were packed. 相似文献
9.
The present study sought to evaluate the effectiveness of vermicomposting for the valorization of distilled grape marc, one of the main solid by-products of the winery sector during a 56-day pilot-scale trial. The increase in the density and biomass of earthworms (Eisenia andrei) during the earlier stages of the process reflected the suitability of the distilled marc (Vitis vinifera L. cv. Mencía) as feedstock in order to sustain large earthworm populations on a pilot-scale level. Supporting this, from 14 days onwards the pH of Mencía distilled marc fell within weak-alkaline levels and the electrical conductivity was between 0.21 and 0.11 mS cm−2 providing optimum conditions for earthworm growth. A rapid decrease in microbial activity as well as in the content of total polyphenols, both indicative of stabilized materials was also recorded after 14 days of vermicomposting. Moreover, the content of macro- and micronutrients in the end product matched with those considered to have the quality criteria of a good vermicompost with respect to plant health and safe agricultural use. Altogether, it underlines the feasibility of vermicomposting as an environment-friendly approach for the biological stabilization of distilled grape marc fulfilling both environmental protection and fertilizer production. 相似文献
10.
Solidification of sewage sludge has been actively investigated in Japan and Europe since the 1970s. Most previous studies
have focused on only the mechanical aspects of potential alternative cover soil made using sewage. Most solidification processes,
however, suffer from severe odor problems because of the high alkalinity of the material. The objectives of this study are
to develop a cost-effective solidifying agent for conversion of sewage sludge in order to reduce the odor generation, as an
alternative to the conventional cement lime-based solidifying agent, and to demonstrate its applicability in the field experimentally.
Field test results showed compressive strength well above the 1.0 kg/cm 2 criterion for landfill cover soil in Korea. Also, the permeability coefficient was far below the 5 × 10 −5 cm/s design criterion for landfill cover soil. Even in harsh weather conditions, such as in winter and summer, the compressive
strength was increased. In addition, the permeability was decreased from 3.45 × 10 −6 cm/s to 4.78 × 10 −7 cm/s, and from 2.27 × 10 −6 cm/s to 3.62 × 10 −7 cm/s, at 7 days after placement in January and August, respectively. It can therefore be postulated that the proposed solidification
process is an appropriate alternative for production of daily landfill cover material. Concerning the odor problem, 5 min
of mixing of sewage with TS103, one of the proprietary agents used in this work, was sufficient to suppress the concentration
of ammonia emitted to below 10 ppm. Considering all of these experimental field test results, it is expected that the proposed
method could be a competitive approach for manufacture of alternative landfill cover material. 相似文献
11.
A sample of polyvinyl chloride (PVC) powder was milled with CaO powder in a planetary mill for various mill operational parameters.
The milled product consisted of dechlorinated hydrocarbon and water-soluble CaOHCl. The dechlorination rate of PVC was determined
by the concentration of Cl − ions measured in solution after dispersing the milled product in water. To evaluate the power consumption during PVC dechlorination,
the mill power consumption was measured during each experimental run. In addition, media motion during planetary milling was
simulated using the discrete element method (DEM), enabling calculation of the mill power consumption. The power consumption
calculated by the DEM simulation compared well with the power consumption measured experimentally. The dechlorination rate
correlated well with the specific mill power consumption, regardless of the sample weight. The dechlorination rate of PVC
when milled with oyster shells (CaCO 3) was observed to be faster than that of the PVC/CaO system, and oyster shells could be used as a reactant for the treatment
of PVC wastes. This work should be useful for the design of a reactor for the dechlorination of PVC.
Chemical Feedstock Recycling & Other Innovative Recycling Techniques 6 相似文献
12.
Chemical recycling of polyamide waste in water was studied using 0.5 L high pressure autoclave at temperatures of 150, 200,
210, 220,230 and 240 °C and at various pressures of 100, 200, 300, 400, 500, 600 and 700 psi (pound per square inch). Viscosity
average molecular weight of the polyamide waste sample was determined by Ostwald method and recorded as 1.928 × 10 3. The reaction was found to be first order with velocity constant in order of 10 −2 min −1. The velocity constant and percent conversion of depolymerization reaction at 240 °C and 700 psi pressure were recorded as
2.936 × 10 −2 min −1 and 99.99% respectively. The velocity constant was obtained on the basis of measurement of amine value. Kinetic and thermodynamic
parameters such as energy of activation, frequency factor, enthalpy of activation were found to be 10.6 kJ mole −1, 0.3719 min −1 and 6.3 kJ mole −1 respectively, at the optimum conditions for maximum depolymerization of polyamide waste. 相似文献
13.
A process of partial nitrification and denitrification in a sequencing batch reactor (SBR) treating leachate was simulated
by applying a modified version of activated sludge model no. 3 (ASM3), named ASM3_2step. This model modifies the ASM3 model
by separating nitrification and denitrification into two steps with nitrite as an intermediate substrate. Three periods, including
long term period, steady state and cycle evolution, were used for calibration. Three main processes were observed, including
biomass production, nitrification (focusing on nitrite accumulation) and denitrification. The kinetic and stoichiometric parameters
(
m \textA_NH \mu_{{{\text{A\_NH}}}} ,
Y\textA_NH Y_{{{\text{A\_NH}}}} ,
Y\textA_\textNO2 Y_{{{\text{A}}\_{\text{NO}}_{2} }} ,
Y\textH_\textO2 Y_{{{\text{H}}\_{\text{O}}_{2} }} , b
A,
K\textA_NH K_{{{\text{A\_NH}}}} ), were determined from biokinetic and respirometry tests. Some of the default values of kinetic and stoichiometric parameters
available in the ASM3 model and in the literature were kept constant, while some others were adjusted step by step until observed
state variables fit with experimental data. The maximum specific growth rate of nitrite oxidizing bacteria (0.108 day −1) (simulated by the model) and that of ammonium oxidizing bacteria (0.61 day −1) (from biokinetic tests) are the parameters which have the highest influence on the nitrite accumulation, even more than
oxygen supply intensity or Kla value. Other important parameters were
K\textAO_NH K_{{{\text{AO\_NH}}}} and
K\textAO_\textNO2 K_{{{\text{AO}}\_{\text{NO}}_{2} }} , calibrated at the values of 1.37 and 1.59 mg O 2/L, respectively. The modified model and values of the kinetic and stoichiometric parameters obtained from the modeling process
will be used for optimization of the partial nitrification in the next study. 相似文献
14.
The objective of the study was to develop a low cost and environmentally friendly liner system for a landfill bioreactor to
harness energy from waste. The landfill bioreactor test cell was constructed and evaluated for performance under dry tropical
conditions of Sri Lanka. The research was carried out from March 2009 to September 2010. The clay-waste polyethylene-clay
composite liner system was developed and permeability was tested. The permeability values of the liner under both saturated
and unsaturated conditions at the high estimated hydraulic head of 86.2 cm were in between 6.3 × 10 −8 and 2.6 × 10 −8 cm/s. The permeability of the liner under waste filled condition varied between 2.17 × 10 −9 and 8.15 × 10 −9 cm/s, which satisfies the standard permeability value. Thus, the results were below the minimum requirement at very high
estimated leachate head. After loading the test cell, leachate and permeate characteristics were analyzed for 273 days, from
January 2010 to September 2010. The study showed the relationships among various parameters including pH, electrical permeability,
chemical oxygen demand, biological oxygen demand, ammonia, nitrate, phosphate, total solids, volatile solids, total suspended
solids and volatile suspended solids. The results of the analysis indicated that there are significant differences in the
values of leachate and permeate parameters. The permeate parameters had values very much lower than those of leachate. It
reveals that the clay-waste polyethylene-clay composite liner system reduced the concentration of these parameters when the
leachate passed through the liner. The biofilm formed in waste polyethylene within the liner may have degraded most of organic
materials found in the leachate when it passed through the liner. Therefore, the clay-waste polyethylene-clay composite liner
system can be applied for full scale landfill bioreactors, particularly for Asian developing countries, due to better performance
and more environmentally friendly characteristics. 相似文献
15.
Liming and/or application of specific nutrients have been proposed as countermeasures to the acidification of forest soils
in southern Sweden. In this study the stem growth of Picea abies (L.) Karst. growing on acidic mineral soils in SW Sweden was investigated 10 years after additions of lime (Ca; 3000 kg lime
ha −1), lime plus P (25 kg ha −1) and K (80 kg ha −1), or N in low doses (2 × 10 kg ha −1 yr −1) (treatments: CaPK, Ca, N, CaPKN, and 2Ca2P2K, respectively). Compared with the control, stem growth was increased following
all treatments involving lime additions, including liming alone. The PK addition did not seem to affect growth. The most plausible
cause of the observed growth increases was that the lime additions indirectly increased the supply of plant-available N. The
annual low-dose N addition did not significantly affect growth. This suggests that air-borne deposition of N, which supplies
very small doses of N throughout the year, has a minor or even negligible influence on P. abies growth. 相似文献
16.
In 1989, a watershed acidification experiment was begun on the Fernow Experimental Forest in West Virginia, USA. Ammonium
sulfate fertilizer (35.5 kg N ha −1 yr −1and 40.5 kg S ha −1 yr −1) was applied to a forested watershed (WS3) that supported a 20-year-old stand of eastern deciduous hardwoods. Additions of
N and S are approximately twice the ambient deposition of nitrogen and sulfur in the adjacent mature forested watershed (WS4),
that serves as the reference watershed for this study. Acidification of stream water and soil solution was documented, although
the response was delayed, and acidification processes appeared to be driven by nitrate rather than sulfate. As a result of
the acidification treatment, nitrate solution concentrations increased below all soil layers, whereas sulfate was retained
by all soil layers after only a few years of the fertilization treatments, perhaps due to adsorption induced from decreasing
sulfate deposition. Based on soil solution monitoring, depletion of calcium and magnesium was observed, first from the upper
soil horizons and later from the lower soil horizons. Increased base cation concentrations in stream water also were documented
and linked closely with high solution levels of nitrate. Significant changes in soil chemical properties were not detected
after 12 years of treatment, however. 相似文献
17.
Ex situ nitrification and sequential in situ denitrification represents a novel approach to nitrogen management at landfills. Simultaneous ammonia and organics removal was achieved in a continuous stirred tank reactor (CSTR). The results showed that the maximum nitrogen loading rate (NLR) and the maximum organic loading rate (OLR) was 0.65 g N l ?1 d ?1 and 3.84 g COD l ?1 d ?1, respectively. The ammonia and chemical oxygen demand (COD) removal was over 99% and 57%, respectively. In the run of the CSTR, free ammonia (FA) inhibition and low dissolved oxygen (DO) were found to be key factors affecting nitrite accumulation. In situ denitrification was studied in a municipal solid waste (MSW) column by recalculating nitrified leachate from CSTR. The decomposition of MSW was accelerated by the recirculation of nitrified leachate. Complete reduction of total oxidized nitrogen (TON) was obtained with maximum TON loading of 28.6 g N t ?1 TS d ?1 and denitrification was the main reaction responsible. Additionally, methanogenesis inhibition was observed while TON loading was over 11.4 g N t ?1 TS d ?1 and the inhibition was enhanced with the increase of TON loading. 相似文献
18.
The degradation of chitosan by means of ultrasound irradiation and its combination with homogeneous photocatalysis (photo-Fenton)
was investigated. Emphasis was given on the effect of additive on degradation rate constants. 24 kHz of ultrasound irradiation
was provided by a sonicator, while an ultraviolet source of 16 W was used for UV irradiation. To increase the efficiency of
degradation process, degradation system was combined with Fe(III) (2.5 × 10 −4mol/L) and H 2O 2 (0.020–0.118 mol/L) in the presence of UV irradiation and the rate of degradation process change from 1.873 × 10 −9−6.083 × 10 −9 mol 1.7 L s −1. Photo-Fenton process led to complete chitosan degradation in 60 min with the rate increasing with increasing catalyst loading.
Sonophotocatalysis in the presence of Fe(III)/H 2O 2 was always faster than the respective individual processes. A synergistic effect between ultrasound and ultraviolet irradiation
in the presence of Fenton reagent was calculated. The degraded chitosans were characterized by X-ray diffraction (XRD), gel
permeation chromatography (GPC) and Fourier transform infrared (FT-IR) spectroscopy and average molecular weight of ultrasonicated
chitosan was determined by measurements of intrinsic viscosity of samples. The results show that the total degree of deacetylation
(DD) of chitosan change, partially after degradation and the decrease of molecular weight led to transformation of crystal
structure. A negative order for the dependence of the reaction rate on total molar concentration of chitosan solution within
the degradation process was suggested. Results of this study indicate that the presence of catalyst in the reaction medium
can be utilized to reduce molecular weight of chitosan while maintaining the power of irradiated ultrasound and degree of
deacetylation. 相似文献
19.
Three different laboratory bioreactors, each duplicated, with dimensions 0.5 × 0.5 × 1 m were set up and monitored for 160 days. Municipal Solid Wastes with an organic content of ~80 % and a density of 550 kg/m 3 were placed in bioreactors. Fresh leachate collected from waste collection vehicles was used with a recirculation rate of 28 L/day. Aerobic bioreactors were aerated at a rate of 0.15–0.24 L/min/kg of waste. Almost the same level of treatment was observed in terms of chemical oxygen demand reduction of leachate, which was in the range of 91–93 %. However, for anaerobic bioreactor, it took almost twice the time, 160 vs. 76 days, to reach the same level of treatment and stabilization. The behavior of semi-aerobic bioreactor was somewhere between the aerobic and anaerobic ones. Total biogas production for anaerobic bioreactors was 90 L/kg of waste, which contained 57–63 % methane. Methane concentration measured in semi-aerobic bioreactor was below 5 %. The main advantage of aerobic bioreactor was the fast rate of the process, while for semi-aerobic bioreactor, it was the elimination of the need for energy to maintain aerobic conditions, and for anaerobic bioreactor it was the production of biogas and potential energy recovery. 相似文献
20.
This study investigates the fate and behavior of lead (Pb), copper (Cu), antimony (Sb), and arsenic (As) in a shooting range
soil. The soil samples were collected from the surface (0–15 cm) and the subsurface (15–40 cm and 40–55 cm) of a grassy and
wood chip covered impact area behind a firing position. Optical microscopy images indicate significant amounts of corroded
bullet fragments and organic wood chips in the surface soil. Analysis by X-ray powder diffraction (XRPD) and scanning electron
microscopy electron dispersive X-ray spectroscopy (SEM-EDS) showed that metallic Pb was transformed into lead oxides (litharge
PbO and massicot PbO) and lead carbonates (hydrocerussite Pb 3(CO 3) 2(OH) 2, cerussite PbCO 3, and plumbonacrite Pb 5(CO 3) 3O(OH) 2). Rietveld quantification indicated the surface soil contained 14.1% metallic Pb, 17.9% hydrocerussite, 5.2% plumbonacrite,
5.9% litharge, and 3.9% massicot on a dry weight basis, or a total of 39.7% Pb, far in excess of lead concentrations typically
found in US shooting range soils. Metallic Cu (bullet jacket material) appeared stable as no secondary minerals were detected
in the surface soil. As and Sb concentrations were on the order of 1,057 mg/kg and 845 mg/kg respectively. The elevated soil
pH coupled with high organic carbon content is thought to have caused downward migration of metals, especially for Pb, since
4,153 mg Pb/kg was observed at a depth of 55 cm. More than 60% of Pb was concentrated in the coarse soil (> 0.425 mm) fraction,
suggesting soil clean-up possible by physical soil washing may be viable. The concentrations of Pb, As, and Sb in the toxicity
characteristic leaching procedure (TCLP) extracts were 8,869 mg/L, 6.72 mg/L, and 6.42 mg/L respectively, were above the USEPA
non-hazardous regulatory limit (As and Pb) of 5 mg/L. The elevated Sb and As concentrations draw concern because there is
historically limited information concerning these metals at firing ranges and several values exceeded local soil cleanup criteria.
As the high Pb concentrations appeared to be linked to the presence of organic-rich berm cover materials, the use of wood
chips as berm cover to prevent soil erosion requires reconsideration as a shooting range management practice. 相似文献
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