ISSN:0278-4491    

DOI:10.1002/ep.670060402

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

ISSN:0278-4491    

DOI:10.1002/ep.670060403

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

ISSN:0278-4491    

DOI:10.1002/ep.670060404

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractProcess condensate wastewaters from two fixed‐bed gasifiers have been treated successfully using a laboratory‐scale, fixed‐film, fluidized‐bed bioreactor. Both dilute (1 to 2% raw wastewater) and more concentrated (50% stripped wastewater) were treated continuously for periods of one to three months. Biological activity was stable, recovery from upsets was rapid, and reaction rates were high due to the high concentration of microorganisms retained on the support particles. Removal of phenolics exceeded 99%, and removal of chemical oxygen demand was typically 75 to 85% for the 50% stripped wastewater with a hydraulic residence time in the bed of ˜5 to 7 h. Sludge production rates were comparable to rates in suspended growth

ISSN:0278-4491    

DOI:10.1002/ep.670060405

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractRisk assessments are one component in the evaluation of potential impacts of remedial alternatives at Superfund sites. They inherently involve uncertainty and incomplete scientific understanding. There is general agreement in the risk assessment community on the broad categories of activities to be performed (i.e., exposure, hazard, and risk assessments), but the method of analysis for each element within an activity is presently not uniformly established. The objective of this paper is to describe judgmental decisions that must be made by the risk assessors during the design and execution of a Superfund site assessment, with a focus on the issues of uncertainty and exposure scenarios. The assessment at Western Processing, Washington, is used as an example of the substantial expert judgment required in choosing the analytical methods and appropriate assumptions.

ISSN:0278-4491    

DOI:10.1002/ep.670060406

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractAttention is presently being focused on the fates of organic chemicals in biological treatment systems. Most systems have been designed and operated to remove organic compounds from the aqueous waste stream and performance has been defined in terms of removal of a non‐specific parameter from the wastewater. Parameters like total organic carbon, biochemical oxygen demand, and chemical oxygen demand have historically been used in treatability studies, in system design, and in determining system performance. Performance data using these approaches are inadequate for determination of the removal of specific compounds unless (fortuitously) the specific compound's biological activity is approximated by the generalized activity of the non‐specific parameter.The resulting assumption that the biokinetics, and therefore the fate of organic compounds, are similar and well‐described by the biokinetics of the non‐specific parameter does not hold for specific chemicals that possess strong stripping/volatilization and/or biomass sorption tendencies or for compounds that have biotransformation kinetics that differ from the idealized “BOD‐like” compound.Some compounds are likely to preferentially strip/volatilize or sorb onto biomass either if generally recalcitrant to biotransformation, or if the biotransformation process is variable and the rates of the competitive fate mechanisms are large relative to the low transient biotransformation rate. All of the above cases have been experimentally documented and will be discussed. The biotransformation rates have the greatest magnitude of variation of any fate‐related parameter and therefore have a major influence on the compound fate. An equation coupling the competitive fates of organic chemicals in completely‐mixed and steady‐state biological treatment systems has been developed and is presented. This equation can be arranged to allow calculation of the fraction or percentage of an organic compound fed to a system that strips, sorbs onto biomass, biotransforms, or remains in the effluent if the stripping, sorption, and biotransformation rates are known. It can be used to correct experimental data to account for the competitive mechanisms and generate more reliable biotransformation data. Finally, it also serves as a unifying approach against which the specific fate performance of a given system may be compared. Therefore it may be used to estimate potential organic air emissions and the potential of toxic organics in sludge generated from the biological wast

ISSN:0278-4491    

DOI:10.1002/ep.670060407

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractOzone, due to its characteristics as a powerful oxidant, has found use in the destruction of toxic organic compounds in wastewater. Its use has been limited however, because of ozone's rapid decomposition and low solubility in water. The ozonation process may be more efficiently carried out in a two‐phase system. The second phase consists of a reusable, fluorinated hydrocarbon, with an ozone solubility of 12–14 times that of water. The fluorinated solvent serves as both an ozone source and a non‐aqueous phase in which the oxidation occurs. With this novel two‐phase process, it is also possible to perform selective oxidation. The experimental results are presented for organic compounds such as phenol, naphthol, etc. The extent of degradation is measured in terms of pH changes, HPLC,

ISSN:0278-4491    

DOI:10.1002/ep.670060408

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractEngineering practices applicable to Superfund sites, as viewed in the context of the institutional policies that guide them are discussed below. Past practice has relied heavily on land disposal of wastes removed from uncontrolled hazardous waste sites. The requirements of the 1984 Hazardous and Solid Waste Amendments (HSWA) to the Resource Conservation and Recovery Act however, have caused land disposal to be the option of last choice. Indeed, the HWSA's general policy directives have established the overall environmental goal of drastically reducing dependence on land disposal for all forms of hazardous waste. As a result, a new set of waste treatment/disposal priorities has been implemented for Superfund site Remedial Actions. The first priority is reuse or recycling of waste, the second is waste destruction, and the third is waste immobilization. The paper outlines the steps for selecting waste treatment processes for Superfund sites and distinguishes between in situ and mobile technologies.

ISSN:0278-4491    

DOI:10.1002/ep.670060409

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractDifferent options and strategies for managing hazardous waste risks are presented. Experience in Massachusetts under a state “Superrfund” law (Chapter 21E) as applied to the selling, buying, and financing of real estate is drawn upon.The sites in question are not “Superfund” sites. They are those commonly found in a state with a history of many old industries as well as with the expected number of gas stations with underground tanks. The approach discussed is that with a thorough site assessment involving historical research and if required, soil and ground water examination, the parties (sellers, buyers, and lenders) through use of a variety of special devices may successfully consummate real estate transactions. These devices include use of indemnification agreements, escrow funds, title insurance, and in some cases involve accomplishment of tank and contaminated soil removal before closing the real estate transaction.Not following this course of action exposes some or all of the parties to the risk of liability for cleanup costs as well as for claims by other parties to the tran

ISSN:0278-4491    

DOI:10.1002/ep.670060410

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY

摘要:

AbstractThis article focuses on the use of ozone for the elimination of dissolved organic pollutants from water and wastewaters. The physical and chemical phenomena prevailing during the contact of a polluted liquid stream with gaseous ozone‐air or ozone‐oxygen mixture in empty or packed columns is represented mathematically. The simulation procedure is based on defining the concentration profiles of ozone and the organic solutes in both liquid and gas phases by means of differential mass balances. Methods for the determination of necessary model parameters is outlined and the model is analyzed for its sensitivity to various process variab

ISSN:0278-4491    

DOI:10.1002/ep.670060411

出版商:American Institute of Chemical Engineers    

年代:1987

数据来源: WILEY