摘要:

ABSTRACTAs a result of the former burning of hazardous chemical wastes in the open air along the border of lake IJmeer, located southeast of Amsterdam, the surrounding environment was contaminated with a variety of organic substances. The major contaminants detected were solvents, volatile aromatics, organochlorine pesticides, arsenic, PCBs, PAHs and PCDDs/PCDFs. For the purpose of risk assessment, several pathways for the migration of hazardous substances were identified. Both site-specific total-lifetime cancer risk and total acceptable daily intake were calculated. The relative contribution of the PCDDs/PCDFs to the total acceptable daily intake was 50.1%. In addition, their contribution to the total-lifetime cancer risk amounted to more than 98%.It is concluded that without remedial action neither the total-lifetime carcinogenic risk nor the total acceptable daily intake would satisfy the minimum health protection goals of 10−6and 300%, respectively. Complete removal of the residues from burning and of the adjacent lake sediments turned out to be the remedial action plan offering the greatest degree of public health protectio

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.1

年代:1995

数据来源: MAL

摘要:

ABSTRACTIn situchemical oxidations have the potential for rapidly treating soils contaminated with toxic and persistent organic wastes. One mechanism for introducing strong oxidants into contaminated soils is the catalyzed decomposition of hydrogen peroxide (H2O2) to form hydroxyl radical (OH•), commonly known as Fenton's reagent. The research presented in this paper investigated the injection of H2O2at depth for treating soil. A scale model injection system was designed and constructed to deliver the H2O2at depth. The tests were conducted in a polyethylene test tank. A natural sand from southeastern Washington state was placed in the tank under controlled density conditions and saturated with nitrobenzene, a documented hydroxyl radical probe. H2O2was injected at a controlled flow rate through a Teflon rotary injection system. Bottom up injection was used for all tests. Pore fluid samples were extracted using thirty in-place glass sampling tubes placed at various depths and distances from the injection axis. Concentrations of nitrobenzene and H2O2were measured to evaluate the influence of flow rate and H2O2concentration on the effectiveness of thein situdelivery syste

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.15

年代:1995

数据来源: MAL

摘要:

ABSTRACTThe majority of the biotreatability studies has been confined to laboratory flask assay level. However, these studies may not provide sufficient information for extrapolation to full-scale bioremediation. In this study, laboratory soil columns were used to closely simulate in-situ field conditions and predict the fate of certain aromatic compounds under denitrifying conditions. The soil columns, after sufficient acclimation period, metabolized toluene rapidly with concomitant nitrate consumption. Approximately 6.48 moles of nitrate was utilized per mole of toluene metabolized. This stoichiometry suggested that about 90% of the substrate was mineralized. Increasing the toluene loading rate from 23.4 to 93.5 mg/kg soil/day had no detrimental influence on the microbial degradative capabilities. When sufficient time was allowed for acclimation, the soil microbiota was able to cross-adapt to degrade other aromatic substrates including ethylbenzene, 2-, and 3-fluorobenzoic acid, and 2-, and 3-chlorophenol but was ineffective for degrading o-xylene, 2,3-dichlorophenol (DCP), 3,4-DCP and 3,5-DCP. These findings help explain the fate of these organic contaminants in anoxic environments.

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.27

年代:1995

数据来源: MAL

摘要:

ABSTRACTDestructions of butanone and toluene are investigated at a low temperature over a catalyst composed of Pt, Ni and Cr alloy of foam type. These odorous volatile organic compounds are subjected to oxidation as single components and as a binary mixture at temperatures in the range 120-220 °C to investigate the effects of destruction. The concentrations of emitted volatile organic compounds are analyzed with a gas Chromatograph. The first-order behavior of butanone and toluene causes inhibition of reactions in the mixture. The inhibition is insignificant at temperatures greater than 165°C. The destruction of the two components individually in the mixture is found to be greater than that of each separate component. Equations for destruction efficiency of single compounds and mixture compounds are derived to predict the efficiency of removal of butanone and toluene in terms of the operating temperature and residence period. Comparisons are made between experiment and results of calculations in a binary mixtur

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.37

年代:1995

数据来源: MAL

摘要:

ABSTRACTDue to its implications for incineration of chlorinated hydrocarbon wastes, the inhibitory effects of CH3Cl on an atmospheric pressure fuel-rich CH4/air premixed laminar flat flame have been studied through stable species concentration measurements and detailed chemical modeling. The chlorocarbon doping results in consistently higher observed CO/CO2ratios. Chemical pathway analyses derived from the detailed mechanistic flame modeling indicates that this inhibition results from the slowdown of CO burnout by OH, and reduced utilization of O2by H. These inhibiting effects are due to consumption of OH and H by HCl, which is generated primarily from fast H abstractions by Cl. The H2formed by the reaction of H with HCl also consumes OH. This represents a shift in product slate away from CO2to H2O.

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.51

年代:1995

数据来源: MAL

摘要:

ABSTRACTA laboratory method was developed to provide an estimate of the amount of hydrogen chloride (HCl) gas formed during waste incineration. The method involves heating the waste sample to 900 °C in a tube furnace, removing particles from the resulting gases by filtration, collecting HCl gas in a water-filled impinger, and measuring the collected HCl as chloride using ion chromatography. The original goal of this project was to develop and evaluate a method that would allow determining, in the laboratory, the amount of HC1 formed upon full-scale incineration of a given hazardous waste feed material. Although the laboratory equipment and procedures performed as designed, the data show that results are very sensitive to materials of construction of the furnace zone, availability of hydrogen, and probably other factors that are difficult to translate accurately from laboratory to full-scale equipment. In particular, the incomplete and variable conversion of inorganic chlorine compounds during incineration makes estimating HCl formation from a real waste highly unreliable. This same variable conversion of inorganic chlorides also makes using any so-called total organochlorine analysis results extremely undependable for estimating HCl emissions. This paper describes the test method developed, the evaluation experiments performed, and the basis for the conclusion that the method is not applicable to accurate prediction of hydrogen chloride emissions from hazardous waste incinerators

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.61

年代:1995

数据来源: MAL

摘要:

ABSTRACTLandfill leachate treatment is the most troublesome aspect of the landfill management Investigation of leachate characteristics at two landfill sites in Taiwan showed that the biological processes were inefficient for the treatment of leachate, regardless of whether an anaerobic or aerobic process was used. In addition, conventional flocculation/sedimentation processes were also ineffective for post-treatment of leachate effluents from biological treatment processes. The discharged leachate still contained lots of refractory pollutants and it failed to meet the effluent quality standards of the ROC. (COD<500 mg/L, NH4+-N<20 mg/L). In an attempt to improve leachate effluent quality, in this study, an electrochemical oxidation process was applied to treat the landfill leachate after biodegradation. Results from both batch and continuous experiments indicate that over 90% of COD and NH4+-N in the landfill leachate are removed by the electrochemical oxidation process. In addition, the electrochemical oxidation process also demonstrated a good efficacy for the removal of refractory compounds. After electrolysis, the chlorinated organic matters (as TOX) in the landfill leachate was reduced from 19.4 to less than 2 mg Cl/L and the BOD/COD ratio of the landfill leachate was also improved from 0.05 to 0.71. These results indicate that the electrochemical oxidation process is a promising process for the treatment of landfill leachate.

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.71

年代:1995

数据来源: MAL

摘要:

ABSTRACTThe use of cement based systems for solidification and stabilization of hazardous wastes has been proposed. The stabilization of Cr contaminated paint removal wastes in ordinary Portland cement and in a Portland cement and blast furnace slag matrix was investigated. A loading by volume of 75% waste and 25% cement (or cement + slag) was used. The expression of pore solution was utilized to determine the chemical environment encountered by the waste species in the cement matrix. The highly alkaline conditions of ordinary Portland cement determined the stability of the metal species, with Cr being highly soluble. The replacement of 25% of the Portland cement by blast furnace slag was found to decrease the [OH-] of the pore solution resulting in a decrease of the Cr concentration. For cement wastes forms hydrated for 28 days, the Cr concentration decreased in the expressed pore solution. During the TCLP tests the cement waste form and extraction solution were found to react, changing the chemistry of the extraction solution. The expression of pore solution was found to give a direct measure of the chemistry of the waste species in the cement matrix. This avoids the reaction of the TCLP extraction solution with the cement matrix which changes the solubility of the hazardous metals.

ISSN:0882-5696    

DOI:10.1089/hwm.1995.12.83

年代:1995

数据来源: MAL