ISSN:1051-5658    

DOI:10.1002/rem.3440100102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractOxygen Release Compound (ORC®) is a patented formulation of intercalated magnesium peroxide that releases oxygen slowly when hydrated. ORC treatment represents a “low intensity” approach to site remediation. It provides a simple, passive, low‐cost and long‐term acceleration of aerobic natural attenuation and has been shown to cost‐effectively reduce time to site closure. ORC is now a proven technology as evidenced by its five years of use on over 5,000 sites in 50 states and 11 countries, and the existence of a full body of independent, peer reviewed literature on its performance.The first applications of ORC were for the treatment of benzene, toulene, ethylbenzene, and xylene (BTEX) and other light petroleum hydrocarbon fractions. Use has now expanded to the treatment of heavier fractions such as heating oil and some of the Polycyclic aromatic hydrocarbons (PAHs). More recently. ORC has been used to bioremediate the highly mobile and problematic gasoline oxygenate methyl tertiary butyl ether (MTBE) and has been applied to sites impacted with nitroaromatics, chloroaromatics, and some of the lower‐order chlorinated hydrocarbons that can be treated aerobically—most notably vinyl chloride.Since ORC is an insoluble powder, it can be packaged in material composed of a specially designed filter fabric. These “filter socks” are then contacted with contaminated groundwater via an array of wells or trenches. ORC can also be mixed directly with water to form a slurry for permanent injection applications in the saturated zone or dispersed in powdered form for the in‐situ or ex‐situ treatment of soil. A broad array of treatment points, in which ORC slurry is backfilled or injected, can be implemented with low‐cost, small‐bore push‐point technologies to directly treat dissolved phase plumes and moderate levels of sorbed contaminants. Powder or slurry is traditionally used in the remediation of residual contamination at the bottom of contaminated soil excavations.

ISSN:1051-5658    

DOI:10.1002/rem.3440100103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractHydrogen Release Compound (HRC®) is a simple, passive, low‐cost, and long‐term option for the anaerobic bioremediation of chlorinated hydrocarbons (CHs) via reductive dehalogenation. Applications to the remediation of other compounds, such as MTBE and perchlorate, that are anaerobically degradable by other reductive mechanisms, are in progress. HRC should be viewed as a tool for the acceleration of natural attenuation at sites that would otherwise require high levels of capital investment and operating expense.HRC is a proprietary, food‐quality, polylactate ester that, upon being deposited into the subsurface, slowly degrades to lactic acid. Lactic acid is then metabolized to hydrogen, which in turn drives the reductive dechlorination of CHs. This has been demonstrated effectively in the laboratory and in the field. HRC can be manufactured as a moderately flowable, injectable material, or as a thicker, implantable hard gel, to facilitate localized treatment and passive barrier designs. HRC is best utilized for the remediation of dissolved phase plumes and the associated hydrophobically sorbed contaminant. The use of HRC is not appropriate for use on free‐phase DNAPL unless the total mass to be remediated is within the scope of economic feasibility in comparison to alternative treatments.Evidence suggests there is competition between reductive dehalogenators and methanogens in which the methanogens compete for the use of hydrogen in the conversion of carbon dioxide to methane. Some researchers believe that a low concentration of hydrogen favors the reductive dehalogenators and starves out the methanogens. The objective, therefore, is to keep hydrogen concentrations low. The time‐release feature of HRC, which is based on the hydrolysis rate of lactic acid from the ester and the subsequent lag time to hydrogen conversion, facilitates this objective. HRC, therefore, becomes a passive form of accelerated natural attenuation, in contrast to the more capital‐and management‐intensive alternatives now available. Laboratory and field results are presented, the latter expanding on the first uses of HRC by various members of the engineering and consulting firm community. © 1999 John

ISSN:1051-5658    

DOI:10.1002/rem.3440100104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractAs the number of leaking underground fuel tank sites with methyl tertiary butyl ehter (MTBE) contamination continues to grow, there is a need to develop cost‐effective solutions for treatment of soil and water contamination. MTBE poses special challenges because of its physicochemical properties, in particular high solubility and low Henry's constant, low affinity for sorption, and very slow rate of microbial degradation. Advanced oxidation processes tend to generate undesirable by‐products. Based on laboratory studies with hollow fiber membranes (HFM), a field‐scale unit was constructed and tested at a number of sites, to determine the effectiveness of this technology in dealing with MTBE contamination. In addition, to treat the soil contamination, the HFM unit was coupled with a Spray Aeration Vapor Extraction (SAVE) unit, which is based on an internal combustion engine. The engine provides the means to treat soil vapors, as well as organic vapors from the spray aeration and HFM units. The overall treatment objectives of 5μg/l for MTBE and 1 μg/l for benzene were achieved with a treatment train consisting of an ion exchange unit, a spray aeration system, a hollow fiber membrane module and two granular activated carbon (GAC) units, for flowrates ranging from 3.8 to 30 l/min (1 to 8 gal/min). The ion exchange unit sewed to reduce water hardness and avoid scaling in the subsequent treatment units, extending the run‐time of the entire system. Overall removal efficiencies for the spray aeration system and hollow fiber membrane module ranged from 85 to over 99 percent. High removal efficiencies (>97%) were obtained at elevated water temperatures (54°C) or lower flowrates (up to 11 l/min). The GAC units were used only to polish the effluent and meet the discharge requirements. Soil, water, and gas phases are treated with this system. Cost estimates are provided for similar treatment processes, for water flowrates up to 38 l/min (10 gal/min). © 1999 John Wile

ISSN:1051-5658    

DOI:10.1002/rem.3440100105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractThe extent of natural dechlorination varies widely in sediments and fails to reach its maximum potential. Recent laboratory and field studies have suggested that the potential for further dechlorination is low in the Hudson and St. Lawrence Rivers. Laboratory investigations have also indicated that polychlorinated biphenyl (PCB) dechlorination is directly coupled to the growth of dechlorinating microorganisms in that: (a) there was no growth of dechlorinating microorganisms below the threshold concentration, (b) the rate of chlorine removal per gram sediment was significantly correlated to the growth rate of the microorganisms, (c) the negative effect of lower moisture levels on dechlorination was correlated to the microorganism death rate, and (d) the extent of natural dechlorination in the St. Lawrence River appears to be related to the in‐situ population size of dechlorinators. There also appear to be many dechlorinating populations, each with different requirements and competence. Therefore, the growth enhancement of these microorganisms is the key to promoting PCB dechlorination either in situ or ex situ. © 1999 John Wiley&Sons, I

ISSN:1051-5658    

DOI:10.1002/rem.3440100106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractCleanup levels at hazardous waste sites are typically developed based at least in pan on either generic or site‐specific risk assessments. Risk assessment in its purest form should be a measure of the potential for a site to cause adverse effects and therefore should be used as the basis for cleanup. However, the process of risk assessment continues to be subject to problems, primarily related to inherent uncertainties in the exposure parameters and toxicity criteria that are the building blocks of the risk assessment. Criticism of risk assessments and risk‐based decisions range from comments that the process inadequately protects human health to comments that the process is overly protective, and examples of both ends of the spectrum are readily available. Site remediation professionals should be aware of the issues related to uncertainty and understand the potential problems in order to ensure appropriate and effective site cleanup. © 1999 John Wiley&Sons,

ISSN:1051-5658    

DOI:10.1002/rem.3440100107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractThe current study describes an improved method for estimating the abundance of polycyclic aramatic hydrocarbon (PAH) degraders in contaminated soil and groundwater. Since the method is a simple incremental improvement to a commonly used approach, it can be easily introduced into the remediation practitioner's testing protocols by simply changing growth indicator dyes. The procedure described is relatively easy to conduct and provides an important addition to laboratories that are using conventional, nonmolecular techniques for microbial enumeration in their bioremediation programs. © 1999 John Wiley&Sons, Inc

ISSN:1051-5658    

DOI:10.1002/rem.3440100108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

摘要:

AbstractIon exchange (IX) can be used to aid in the remediation of underground storage tank (UST) radioactive waste at the U.S. Department of Energy's Hanford site in the state of Washington. In particular, IX can be used to concentrate the radionuclides in liquid‐based waste prior to immobilization for final disposal. Concentration of the radionuclides can significantly reduce the final immobilized high‐level waste volume and consequent overall remediation cost. Organic and inorganic IX resins each have unique advantages and disadvantages regarding the remediation process. This study presents a comparison of the remediation cost for UST waste at Hanford for a phenol‐formaldehyde type organic resin versus crystalline silico‐titanate inorganic resin. It was determined that with optimum processing conditions such as waste blending and sludge washing, remediation with the inorganic resin would be less expensive than the organic resin. Assuming baseline remediation conditions, the use of inorganic rather than organic IX resin for UST remediation at Hanford can save approximately $383 million. A limited sensitivity analysis was performed as pan of this study and is reported in the following. © 1999 John Wiley&S

ISSN:1051-5658    

DOI:10.1002/rem.3440100109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

ISSN:1051-5658    

DOI:10.1002/rem.3440100110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY

ISSN:1051-5658    

DOI:10.1002/rem.3440100101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1999

数据来源: WILEY