Methodology and model for performance and cost comparison of innovative treatment technologies at wood preserving sites

Wood preserving facilities have used a variety of compounds, including pentachlorophenol (PCP), creosote, and certain metals, to extend the useful life of wood products. Past operations and waste management practices resulted in soil and water contamination at a portion of the more than 700 wood preserving sites in the United States (EPA, 1997). Many of these sites are currently being addressed under federal, state, or voluntary cleanup programs. The U.S. Environmental Protection Agency (EPA) National Risk Management Research Laboratory (NRMRL) has responded to the need for information aimed at facilitating remediation of wood preserving sites by conducting treatability studies, issuing guidance, and preparing reports. This article presents a practical methodology and computer model for screening the performances and comparing the costs of seven innovative technologies that could be used for the treatment of contaminated soils at user‐specified wood preserving sites. The model incorporates a technology screening function and a cost‐estimating function developed from literature searches and vendor information solicited for this study. This article also provides background information on the derivation of various assumptions and default values used in the model, common contaminants at wood preserving sites, and recent trends in the cleanup of such sites. © 2001 John Wiley & Sons, Inc.     

Solidification/stabilization for remediation of wood preserving sites: Treatment for dioxins,PCP, creosote,and metals

This article discusses the use of solidification/stabilization (S/S) to treat soils contaminated with organic and inorganic chemicals at wood preserving sites. Solidification is defined for this article as making a material into a freestanding solid. Stabilization is defined as making the contaminants of concern nonmobile as determined from a leaching test. S/S then combines both properties. For more information on S/S in general the reader should refer to other publications (Connors, J.R. [1990]). Chemical fixation and solidification of hazardous wastes. New York: Van Nostrand Reinhold; US Environmental Protection Agency. [1993a]. Engineering bulletin solidification/stabilization of organics and inorganics (EPA/540/S‐92/015); Wiles, C.C. [1989]. Solidification and stabilization technology. In H.M. Freeman [Ed.], Standard handbook of hazardous waste treatment and disposal. New York: McGraw Hill) as this article addresses only wood preserving sites and assumes basic knowledge of S/S processes. For a more general discussion of wood preserving sites and some other remedial options, the reader may wish to refer to a previous EPA publication (US Environmental Protection Agency. [1992a]. Contaminants and remedial options at wood preserving sites [EPA/600/R‐92/182]). This article includes data from the successful remediation of a site with mixed organic/inorganic contaminants, remediation of a site with organic contaminants, and detailed treatability study results from four sites for which successful formulations were developed. Included are pre‐ and post‐treatment soil characterization data, site vaines. ileizdot‐ names (in some cases), treatment formulas used (generic aridproprietary), costs, recommendations, and citatioiis to inore detailed refer‐ en ces. The data presen ted iiidica te that dioxins, pentachlorophepi 01 (PCP), creosote, polycyclic aromatic hydrocarbom (PAHsI, and metals can be treated at moderate cost by the use of S/S techuologp.     

Fungicidal value of wood tar from pyrolysis of treated wood

The objective of the paper was to estimate the fungicidal value of wood tar extracted as a product of pyrolysis of wood previously treated with either creosote oil or CCB-type salt preservative. The effectiveness of wood treated with one of these two wood tar residuals was compared to the effectiveness of wood treated with virgin creosote oil (type WEI-B) and an untreated control. Wood was impregnated with alcohol solutions of the two extracted preservatives or virgin creosote oil and then subjected to the Coniophora puteana, Poria placenta and Coriolus versicolor fungi. The fungicidal values of the investigated preservatives were determined with the use of the short agar-block method and the aging test according to the standard EN 84. It was found that wood tar extracted by pyrolysis of old creosote-treated wood and then used to treat wood may have potential as a preservative for wood protection or as a component of preservatives.     

Recovery and Microbial Remediation of Organic Wood Preservatives in Groundwater at a Former Wood Treating Plant

Well-recovery networks coupled to immobilized microbe bioreactors (IMBRs) were installed at a 172-acre former wood preserving facility for the bioremediation of organic wood preservatives present in site groundwater. Free-phase creosote from the hardpan and soluble preservative fractions contained in subsurface groundwater were pumped separately to different holding tanks. Trace creosote fractions contained in the subsurface groundwater were further gravity separated in the holding tank. Immobilized microbial isolates evaluated in earlier laboratory and field pilot tests were established into two 40, 000-liter bioreactors for the biodegradation of all targeted consitituents. Microbial growth, dissolved oxygen, pH, nutrients, flow rate, and temperature were monitored in this in situ/ex situ bioremediation system. The process was used to remove the polycyclic aromatic hydrocarbon (PAH) and phenolic components of creosote and pentachlorophenol from contaminated groundwater. Data generated during the past 2 1/2 years indicate that 26 target compounds consistently are reduced to levels acceptable for discharge. Currently operating in Baldwin, Florida, this full-scale prototype is remediating the former wood preserving facility and is being used as a model system for the design and construction of new bioreactor systems needed at similar industrial sites in the United States and abroad.     

Land treatment and the toxicity response of soil contaminated with wood preserving waste

Soils contaminated with wood preserving wastes, including pentachlo-rophenol (PCP) and creosote, are treated at field-scale in an engineered prepared-bed system consisting of two one-acre land treatment units (LTUs). The concentration of selected indicator compounds of treatment performance included PCP, pyrene, and total carcinogenic polycyclic aromatic hydrocarbons (TCPAHs) was monitored in the soil by taking both composited soil samples at multiple points in time, and discrete soil samples at two points in time. The mean concentration of the indicator compounds and the 95-percent confidence interval (CI) of the composite and discrete samples agreed relatively well, and first-order degradation rate kinetics satisfactorily represented the mean chemical concentration loss of indicator compounds in the LTU. Toxicity of the soil, as measured by Microtox^TM assay of the soil extracts, indicated that toxicity reduction corresponded with indicator compound disappearance. No toxicity effects were observed with time in treated layers of soil (lifts) buried beneath highly contaminated lifts of newly applied soil. This indicated that vertical migration of soluble contaminants from such lifts had little effect on the microbial activity in the underlying treated soil.     

Noncombustion technologies for remediation of persistent organic pollutants in stockpiles and soil

Persistent organic pollutants (POPs) are a set of chemicals that are toxic, persist in the environment for long periods of time, and biomagnify as they move up through the food chain. Combustion technologies have been the principal technology used to destroy POPs. However, combustion technologies can create polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzo‐p‐furans, which are human carcinogens. Two organizations, the United Nations Environment Programme (UNEP) and the International HCH and Pesticides Association (IHPA) have developed detailed reports and fact sheets about noncombustion technologies for POP treatment. This article is intended to update and summarize these reports in a concise reader's guide, with links to sources of further information. The updated information was obtained by reviewing various Web sites and documents, and by contacting technology vendors and experts in the field. © 2006 Wiley Periodicals, Inc.     

Solvent extraction and soil washing treatment of contaminated soils from wood preserving sites: Bench‐scale studies

Bench‐scale solvent extraction and soil washing studies were performed on soil samples obtained from three abandoned wood preserving sites included in the National Priority List. The soil samples from these sites were contaminated with high levels of polyaromatic hydrocarbons (PAHs), pentachlorophenol (PCP), dioxins, and heavy metals. The effectiveness of the solvent extraction process was assessed using liquefied propane or dimethyl ether as solvents over a range of operating conditions. These studies have demonstrated that a two‐stage solvent extraction process using dimethyl ether as a solvent at a ratio of 1.61 per kg of soil could decrease dioxin levels in the soil by 93.0 to 98.9 percent, and PCP levels by 95.1 percent. Reduction percentages for benzo(a)pyrene (BaP) potency estimate and total detected PAHs were 82.4 and 98.6 percent, respectively. Metals concentrations were not reduced by the solvent extraction treatment. These removal levels could be significantly improved using a multistage extraction system. Commercial scale solvent extraction using liquefied gases costs about $220 per ton of contaminated soil. However, field application of this technology at the United Creosote site, Conroe, Texas, failed to perform to the level observed at bench scale due to the excessive foaming and air emission problem. Soil washing using surfactant solution and wet screening treatability studies were also performed on the soil samples in order to assess remediation strategies for sites. Although aqueous phase solubility of contaminants seemed to be the most important factor affecting removal of contaminants from soil, surfactant solutions (3 percent by weight) having nonionic surfactants with hydrophile‐lipophile balance (HLB) of about 14 (Makon‐12 and Igepal CA 720) reduced the PAH levels by an average of 71 percent, compared to no measurable change when pure deionized water was used. Large fractioza of clay and silt (<0.06mm), high le!ezielsof orgaizic contami‐ nants and hzimic acid can makesoil washing less applicable.     

THE POTENTIAL FOR RE-USE OF PRESERVATIVE-TREATED UTILITY POLES REMOVED FROM SERVICE

This study investigates the feasibility of re-using or recycling utility poles or parts of poles for solid wood products. Four hundred and fifty-six poles or pole sections, removed from service in Ontario and Quebec, Canada, were characterized by age, wood species, preservative type, residual preservative, dimensions and condition. Based on this characterization, the potential for re-use as round poles or posts, sawn posts, timber, lumber and cedar roof shingles was evaluated. About 8% of the poles can be re-used without reprocessing, 15% of the pole volume can be used for cedar shingles, and about 35% of the pole volume can be converted to sawn products based on the selected hierarchy of preferred uses. Most of the poles removed from service had been treated with pentachlorophenol. The average levels of treatment decreased with age of the poles and approached the toxic threshold retentions in 25-year-old (or older) poles. For older poles (>35 years), creosote was the predominant treatment. Creosote levels were about 50% of the assumed levels when fresh treated. Creosote extracted from these poles contained fewer polynuclear aromatic hydrocarbon components than “new” creosote. The poles treated with chromated copper arsenate (CCA) retained high levels of preservative, even after many years in service. Used poles can be sawn into lumber of a good grade (#2 and better) using a small portable bandsaw. Special sawdust handling and disposal provisions must be made if this use is to be adopted. Treated poles with depleted reserves of creosote or pentachlorophenol could be re-treated with CCA or creosote preservatives to acceptable retentions. The quality of re-treatment was as good or better than that observed with new wood, and the re-treatment should ensure several decades of protection for guide-rail posts and other high decay hazard applications.     

Bioremediation of PCP-contaminated soil: Bench to full-scale implementation

Pentachlorophenol (PCP) is a widely used wood treatment agent and pesticide that is often listed among the contaminants at hazardous waste sites. Bench-scale studies were performed to develop a microbial culture and biodegradative process that could treat PCP at higher concentrations than previously reported. Several substrate formulations and culture techniques were evaluated. Ultimately a “self-feeding” (pH auxostat) continuous culture system (pH auxostat) was used to select for biodegradative activity with PCP as the carbon and energy source. After a period of 50 days, influent PCP concentrations reached 3,500 mg/liter at a dilution rate of 0.066 H^?1. Of the total theoretical chloride that could be released from PCP, 99% was detected as free chloride in the reactor effluent. PCP analysis of the effluent verified complete degradation by the microbial consortium. The reactor was converted to a constant PCP feed. At steady state conditions, the dilution rate was 0.05 H^?1 with an influent PCP concentration of 2,560 mg/liter and a biomass yield of 018 mg (dry weight) per mg of PCP. Mineralization studies performed with the microbial consortium using [U-14C1]-PCP indicated that 36.5% of the label was released as 14C-carbon dioxide.     

Creosote DNAPL Recovery‐Well Design for Mass Removal

Sites with dense nonaqueous‐phase liquid (DNAPL) contamination present significant remediation challenges in terms of technical practicability and cost. Remedial approaches to DNAPL sites often follow a management approach rather than removal or eradication approaches, particularly due to the uncertainties associated with the benefits of partial source mass removal, as complete source removal is unlikely. Mass‐removal technologies should be evaluated for all DNAPL sites, although implementation of recovery technologies will be limited to a few sites based upon site‐specific factors. Sitewide remedial strategies that employ source reduction, where applicable, and incorporate associated risk‐reduction technologies, including monitored natural attenuation, are advised. Creosote DNAPL sites are particularly challenging, as they are predominantly composed of low‐solubility polycyclic aromatic hydrocarbons that form long‐term continuing sources. Additionally, the physical properties of creosote DNAPL, including high viscosity and relatively low density, result in significant migration potential and considerable dissolved‐phase groundwater impacts. An innovative creosote DNAPL source recovery well design was developed to achieve separate‐phase removal of pooled creosote DNAPL. The design presented herein employs modified circulation‐well technology to mobilize DNAPL to the engineered recovery well, where it is gravity‐settled into a sump to permit separate‐phase mass removal of the emplaced DNAPL source without groundwater production or treatment. A discharge mass flux protocol was developed to verify dissolved‐phase plume stability and the benefit of the source mass removal. © 2013 Wiley Periodicals, Inc.     

Evaluation of white‐rot fungi for the remediation of creosote‐contaminated soil

Application of fungal‐based bioaugmentation was evaluated for the remediation of creosote‐contaminated soil at a wood‐preserving site in West Virginia. Soil at the site contained creosote‐range polycyclic aromatic hydrocarbons (PAHs) at concentrations in some areas that exceed industrial risk‐based levels. Two white‐rot fungi (Pleurotus ostreatus and Irpex lacteus) were evaluated for remediation effectiveness in a two‐month bench‐scale treatability test. Both fungi produced similar results, with up to 67.3 percent degradation of total PAHs in 56 days. Pilot‐scale testing was performed at the site using Pleurotus ostreatus grown on two local substrate mixtures. During the 276‐day field trial, total PAHs were degraded by up to 93.2 percent, with all individual PAHs except one achieving industrial risk‐based concentrations. It was recommended that fungal‐based remediation be applied to all contaminated soil at the site. © 2002 Wiley Periodicals, Inc.     

In‐Canal Stabilization/Solidification of NAPL‐Impacted Sediments

In situ solidification (ISS) has been used with increasing frequency as a remedial technology for source area treatment at upland sites impacted with a variety of organic contaminants, including coal tar, creosote, and other nonaqueous phase liquids (NAPLs). With several large, complex, urban water ways and rivers impacted with NAPLs, ISS is more recently being considered as a technology of choice to help reduce remedial costs, minimize short‐ and long‐term impacts of mobile NAPL, and lower the carbon footprint. This article presents the results of a successful pilot study of ISS at the Gowanus Canal Superfund site in Brooklyn, New York. This represents the first major sediment ISS field demonstration project in a saline environment and the first project to evaluate large‐scale implementation of ISS from a barge and through overlaying sediment. ©2016 Wiley Periodicals, Inc.     

Analytical,Risk Assessment,and Remedial Implications Due to the Co‐Presence of Polychlorinated Biphenyls and Terphenyls at Inactive Hazardous Waste Sites

Investigations conducted at three inactive hazardous waste sites in New York State have confirmed the co‐presence of polychlorinated hiphenyls (PCBs) and polychlorinated terphenyls (PCTs) in soils, sediments, and biota. The PCTs at all three sites were positively identified as Aroclor 5432, with the most probable source being the hydraulic fluid Pydraul 312A utilized for high‐temperature applications. The identification of the lower‐chlorinated PCT formulations in environmental samples is problematical, since PCT Aroclors 5432 and 5442 are not chromatographically distinct from the higher‐chlorinated (PCB) Aroclors 1254, 1260, 1262, and 1268 using conventional gas chromatography–electron capture detection. Results from this study indicate that U.S. Environmental Protection Agency (USEPA) approved PCB methods routinely utilized by most commercial laboratories based on Florisil adsorption column chromatography cleanup are inadequate to produce valid chromatographic separation and quantitative results with soils, sediment, and biota samples containing both PCBs and PCTs. The presence of co‐eluting PCBs and PCTs precludes accurate quantitation due to significant differences in PCB/PCT electron capture detector response factors, and the potential for misidentification of PCT Aroclors as higher chlorinated PCB Aroclors. A method based on alumina column adsorption chromatography was used, allowing for the accurate identification and quantitation of PCB and PCT Aroclors. The results of this study suggest that the utilization of alumina adsorption column separation may have applicability and regulatory significance to other industrially contaminated sites which historically used Pydraul 312A. Inferences.     

The treatment of contaminated water at remedial wood preserving sites

Contaminated groundwater and surface water have posed a great challenge in restoring wood preserving sites to beneficial use. Often contaminated groundwater plumes extend far beyond the legal property limits, adversely impacting drinking water supplies and crop lands. To contain, treat, and/or remediate these valuable resources is an important part of restoring these impacted sites. Various options are available for remediating the groundwater and other affected media at these sites. Frequently, pump and treat technologies have been used that can provide well‐head treatment at installed extraction wells. This approach has shown to be costly and excessively time consuming. Some of the technologies used for pump and treat are granular activated carbon (GAC), biotreatment, and chemical oxidation. Other approaches use in‐situ treatment applications that include enhanced bioremediation, monitored natural attenuation (biotic and abiotic), and chemical reduction/fixation. Ultimately, it may only be feasible, economically or practicably, to use hydraulic containment systems. Depending upon site‐specific conditions, these treatment approaches can be used in various combinations to offer the best remedial action. A comparison of water treatment system costs extrapolated from the treatability studies performed on contaminated groundwater from the McCormick/Baxter Superfund site in Stockton, California, yielded operation and maintenance costs of $1.19/1,000 gal. for carbon treatment and $7.53/1,000 gal. for ultraviolet (UV) peroxidation, respectively.     

Status and trends in bioremediation treatment technology

This article is a critical analysis of the treatment potential of bioremediation technology to degrade eight major environmental pollutants, polycyclic aromatic hydrocarbons, phenols, pentachlorophenols, creosote, polychlorinated biphenyls, trichloroethylene, chlorobenzoates, and chlorophenols. The discussion includes information on transformation mechanisms, identification of intermediate metabolites, elucidation of partial or complete pathways, effects of environmental parameters, as well as current and future industrial application. Results indicate that bioremediation used in conjunction with other physical and chemical treatment methodologies can effectively transform most prevalent nonchlorinated organic contaminants and some chlorinated contaminants, such as creosote and pentachlorophenol, into innocuous materials. Successful biodegradation of several other chlorinated organic compounds, notably polychlorinated biphenyls and trichloroethylene, is currently possible only under controlled laboratory conditions. Future successful field applications, however, appear promising.     

Investigation of NAPL transport through a model sand cap during ebullition

Nonaqueous‐phase liquid (NAPL) migration from sediments to the surface of water bodies has been reported frequently at sites with sediments contaminated with NAPLs, such as coal tar and creosote. Commonly, transport of NAPL from sediment is facilitated by gas ebullition caused by anaerobic biodegradation of organic matter in the sediment. A remedy often specified for these sites is a sand cap, and sand caps amended with sorbent materials (such as organoclays) are being pilot‐tested. This article discusses a laboratory study to assess the effectiveness of a sand layer for controlling NAPL migration. The study used a test column composed of a Plexiglas tube containing a tar source that was buried beneath a 30‐cm‐thick layer of fine sand. Water was added to the column until 5 cm of standing water covered the sand layer. To simulate ebullition, air was injected into the base of the sand column at approximately 200 mL/min. It was observed that the gas and NAPL migrated primarily through channels and fractures in the sand, and was not filtered through a network of stable pores. Tar migrated through the sand layer in 12 hours and accumulated on the water surface for several hours before losing its buoyancy and settling back down to the sand surface. After ending the tar migration experiment, the test column was frozen to preserve structures in the sand. The study showed that the tar migrated through the simulated sand cap in small (2‐mm) channels only a few sand grains thick. The results of this laboratory work call into question the effectiveness of sand caps for controlling NAPL migration from sediment in the presence of ebullition. © 2009 Wiley Periodicals, Inc.     

Natural biodegradation of wood preservatives

Natural biodegradation can contain groundwaters impacted by creosote and pentachlorophenol. Using natural biodegradation for such sites is attractive because groundwater restoration is often impracticable, but the dissolved plumes are biodegradable and exert relatively low oxygen demands. Three case studies of its successful use are presented, with emphasis on the types of evidence needed, the rates and extents of removal, and the strategies for incorporating natural biodegradation into a remediation approach. Natural biodegradation was proven at all three sites, using a combination of field geochemical measurements, laboratory simulations, and computer modeling. Contaminant plumes at these three sites were contained within 100 to 700 feet downgradient of the apparent sources, although the rates of biodegradation varied widely. Natural biodegradation should be considered as part of an overall remedial strategy for most sites contaminated by creosote and/or pentachlorophenol.     

Evaluation of the potential of applying composting/bioremediation techniques to wastes generated within the construction industry

The objective of the present study was to evaluate the viability of reducing landfill requirements to satisfy EC Landfill Directive requirements by applying composting/bioremediation techniques to the construction and demolition (C&D) industry waste stream at laboratory scale. The experimental study was carried out in nine test rigs to examine different wood mixtures; untreated timber, creosote treated timber and chromated copper arsenate (CCA) treated timber. Several experimental variables affecting the process were characterised and optimised. These include the best nitrogen additive and optimum moisture content required for composting. Poultry manure was found to be the best nitrogen additive. The optimum moisture content was decreased after the addition of poultry manure. The composting/bioremediation process was evaluated through monitoring the microbial activity, carbon dioxide emissions and toxicity examination of the composted product. A typical temperature profile suggested that untreated and CCA treated mix could be classified as hot composting whereas creosote treated mix could be classified as cold composting. The paper reports on the results obtained during this investigation.     

Controlling Air Toxics Emissions From Remediation by Monitoring of Surrogate Parameters

Particulate matter (dust) from remediation and demolition sites may pose a potential risk to the nearby public due to the presence of various contaminants. Unfortunately, there are no good options for real‐time monitoring of metals, polychlorinated biphenyls, etc. in wind‐blown dust. A three‐tiered approach involving a combination of real‐time monitoring and off‐site analysis that has proved successful is described in this article. PM₁₀ is used as a surrogate parameter for metals and other nonvolatile pollutants, and real‐time monitoring is used to guide dust control measures. If dust emissions are controlled, air emissions of metals and other nonvolatile pollutants also are controlled. © 2014 Wiley Periodicals, Inc.     

Treatment technology for remediation of wood preserving sites: Overview

This is the first in a series of five articles describing the applicability, performance, and cost of technologies for the remediation of contaminated soil and water at wood preserving sites. Site‐specific treatability studies conducted under the supervision of the United States Environmental Protection Agency (US EPA), National Risk Management Research Laboratory (NRMRL), from 1995 through 1997 constitute much of the basis for the evaluations presented, although data from other treatability studies, literature sources, and actual site remediations have also been included to provide a more comprehensive evaluation of remediation technologies. This article provides an overview of the wood preserving sites studied, including contaminant levels, and a summary of the performance of the technologies evaluated. The subsequent articles discuss the performance of each technology in more detail. Three articles discuss technologies for the treatment of soils, including solidification/stabilization, biological treatment, solvent extraction and soil washing. One article discusses technologies for the treatment of liquids, water and nonaqueous phase liquids (NAPLS), including biological treatment, carbon adsorption, photolytic oxidation, and hydraulic containment. The reader should be aware that other technologies including, but not limited to, incineration, thermal desorption, and base catalyzed dehalogenation, also have application for treating contaminants on wood preserving sites. They are not discussed in these five articles since the focus was to evaluate lesser known and hopefully lower cost approaches. However, the reader should include consideration of these other technologies as part of any evaluation or screening of technologies applicable to remediation of wood preserving sites.