bioremediation treatability studies of contaminated soils at wood preserving sites

Bior ernediation Treatability Studies of Contaminated Soils at wood Preserving Sites

Dou,las lic! GYosse Endalkachew Sable-Demessie Edwmd R. Bates

Douglas W Grosse has worked as an environmental engineer at the US. Environmental Protection Agency (EPA) in Cincinnati, Ohio, f o r the past 21 years. Currently, he is working in Technology Transfer by serving as a specialist in site remediation and industrial wastewater treatment. Endalkachew Sahle- Demessie is a research engineer at the US. EPA, National Risk Management Research Laboratory, Cincinnati, Ohio. He has been working on the application of emerging treatment technologies for remediating contaminated soils. Ed- ward R Bates has been with the US. EPA in Cincinnati, Ohio, as a physical scientist since 1977. Since 1989 his principal duties haue been to provide expert technical assistance on all aspects of Superfund site remediation, including characterization, remedy selection, remedy design, and field implementation.

Bioremediatioii has been used frequently at sites contaminated ulith organic hazardous chemicals where releases from processing vessels and the mismanagrment of reagents and generated zuaste h a w contributed to significant iinpairrnent of the environment. At wood tipeater sztes, process reagents such as pentachlorophenol (PCP), and creosote haue adverse<]) impacted the stirrotinding soil andgroundwater. When PCP has been used at these sites, polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofkrans (PCDFsI a m typically found. Where creosote has beeti used as the wood presewatiue of choice, po!ynztclear aromatic h-vdrocar- bons (PAWS) ale common13, found. Many of these compounds are conskl- ered to be persistent. bioaccumulative, and toxic (PBU and are particu- larly recalcitrant. 0 2000 John Wiley & Sons, Inc.

INTRODUCTION The primary focus for the use of bioremediation at wood treater sites

is to decontaminate the recalcitrant cornpounds associated with the former use of pentachlorophenol (PCP) and creosote. Since bioreinediation has shown effectiveness in degrading organic contaminants, the United States Environniental Protection Agency’s (USEPAs) Office of Solid Waste and Emergency Response (OSWER) has selected it as one of the four presumptive remedies for cleaning up wood preserving sites. This article discusses recent advances in the state-of-the-science in applying enhanced bioremediation. Information derived from treatability studies, case studies, and demonstration projects supported by the USEPA’s Office of Research and Development (ORD), National Risk Management Research Laboratory (NRMRL) in Cincinnati, Ohio, focusing on three different applications of bioremediation were evaluated, including (1) land farming, (2) slurry phase, and ( 3 1 bioaugmentation. Although the land-farming treatability

Citation of product, company, or trade names do not constitute endorsement by the US. Environmental J’rotection Agency and are provided only for the purpose of better describing information in this article. Opinions expressed are those of the authors and should not be construed as representing positions or policy of the U S . Environmental Protection Agency.

0 2000 John Wiley & Sons, Inc. 67

DOUGLAS W. GROSSE ENDALKACHEW SAHLE-DEMESSIE EDWARD R. BATES

Historically, bioremediation refers to the enhancement of natural biodegradation by adding selective amendments such as oxygen, nutrients, bulking agents, and microorganisms to degrade the target contaminants.

study (with and without manganese oxide [MnO, I amendment) showed inconclusive results, the demonstration project yielded total carcinogenic polynuclear aromatic hydrocarbon (TCPAH) removal rates greater than 82 percent after 400 days of treatment for two land treatment units. Based on the treatment of 45,000 yd’ , unit treatment cost approximated $35 perydj of contaminated soil. Pilot-scale slurry-phase bioremediation utilizing a 1,125 m3 reactor yielded total mean removal rates of total PAHs greater than 87 percent at a cost of $145/yd3. Treatability studies evaluating biotreatment augmented by Fenton’s Reagent for a mixed sample obtained from a Superfund site showed 78 percent reduction in total PAHs and > 95 percent reduction in benzo(a)pyrene (BAP) potency estimate. Only performance data was available for this treatability study.

BACKGROUND Historically, bioremediation refers to the enhancement of natural

biodegradation by adding selective amendments such as oxygen, nutrients, bulking agents, and microorganisms to degrade the target contaminants. Adjusting soil conditions for moisture content, temperature, mixing, and handling plays a significant role in applying this technology. The technology can be accomplished in-situ or in above- ground treatment areas and/or reactors. Biodegradation can occur aerobically or anaerobically in separate, simultaneous, successive, and/ or intermittent modes. Although aerobic bioreniediation has been widely used, many chlorinated compounds, including PCP, are treated under anaerobic conditions.

Since the wood treating compounds PCP and creosote tend to be persistent in the environment and difficult to treat, application of bioremediation technologies poses significant challenges. Bioreinediation technologies that are applicable to soils, sediments, and sludge can be divided into five general categories: slurry phase, solid phase, composting, in-situ, and phytoreniediation (USEPA,1997).

Slurryphase bioremediation is performed by adding water to the contaminated media and treating under aerobic conditions. Mixing facili- tates contact between the resident microorganisms and contaminants along with providing oxygen throughout the treatment chaniber (bioreactor). Solid-phase bioremediation utilizes conventional agricultural practices such as tilling, fertilizing, and irrigating to accelerate microbial degradation of contaminants in ex-situ or above-ground treatment units. Composting is accomplished by using bulking agents, such as straw or wood chips, to increase the porosity of the contaminated media. Amendments are used to increase the nutrient level by adding degradable organic matter such as manure, and yard and food processing waste. This practice often stimulates the growth of thermophilic microorganisms capable of degrading the subject contaminants of concern. In-situ bioremediation is performed by providing electron acceptors, nutrients, moisture, and other amendments to soils or sediments without displacing the contaminated media. This application is often used in conjunction with groundwater reinediation approaches such as pump-and-treat and soil flushing technologies where

68 REMEDIATION/~UMMER 2000

BIOREMEDIATION TREATABILITY STUDIES OF CONTAMINATED SOILS AT WOOD PRESERVING SITES

Three different bioremediation treatability studies were conducted: (1) land farming with an amendment (manganese oxide), (2) s 1 urry-p hase biotreatment with Fenton’s Reagent, and (3) induced biotreatment via inoculation.

the treated water is further amended and injected into the contaminated zone to stimulate microbial activity. Bioventing is a variation of in-situ bioremediation where either vacuum extraction or air injection wells are installed and operated at relatively low flow rates while providing sustained oxygen to microorganisms in the subsurface. Phytoremediation is another form of bioremediation technology where contaminants are either extracted from the soil and assimilated via plant uptake or degraded through microbial stimulation.

This article evaluates treatability studies that were performed under contract for the NRMRL Remedial Technical Assistance Program. In addition, other case studies are discussed that illustrate the field application of bioremediation (with the exception of phytoremediation). Where applicable, cost information is provided.

TREATABILITY STUDIES Under the NRMRL Remedial Technical Assistance Program, three

Superfund sites were selected for treatability studies using several variations of hioremediation applications for treating soil and other media contaminated with wood treating compounds (USEPA, 1997). Samples of contaminated soil and groundwater were collected at the American Creosote Works (ACW) site in Jackson, Tennessee, the McCormick/Baxter (MCB) site in Stockton, California, and the RAB Valley site in Panama, Oklahoma, for use in the treatability studies. A summary of the principal contaminant concentrations for each of the three test soils is presented in Exhibit 1.

Three different t3ioreniediation treatability studies were conducted: (1 ) land farming with an amendment (manganese oxide), (2) slurry-phase hiotreatinent with Fenton’s Reagent, and (3) induced hiotreatment via inoculation. All of these studies utilized some type of augmentation to facilitate the biotreatment process. Results for each of the three treatability studies, as obtained from laboratory analysis, include measurements for total petroleum hydrocarbons (TPH), semivolatile organics ( SVOCs), and dioxin/furans (I’CDDs/PCDFs) along with calculated toxicity/potency factors for I-’CDDs/PCDFs and PAHs, respectively.

Land Farming with MnO, The land Fdrming treatability study used the oxidizer, manganese oxide

(MnO J , as augmentation, to treat soil contaminated with two wood preservatives, I’CP and creosote (USEPA, 1998). The technical approach is based on the premise that the combined effect of a strong oxidizing agent coupled with the catabolic activities of microorganisms can result in the enhanced degradation of the subject contaminants in soil.

Experimental Design Samples from RAB Valley and MCB soils were collected and analyzed for

SVOCs, PCDDs/PCDFs. and TPH. Four distinct test conditions were established for each of the two sample soils. Each of the four test conditions (see Exhibit 2) were replicated in four individual test pans (32 test pans in total).

REMEDIATION/SUMMER 2000 69

DOUGLAS W. GROSSE ENDALKACHEW SAHLE-DEMESSIE EDWARD R BATES

Analyte ACW RAB

BAPl (mg/kg> 215 75

PCP(mg/kg) 650 1,210

Exhibit 1. Pretreatment Soil Samples (USEPA, 1778)

MCB

55

347

Quantity

1 TEQ2 (ppb) 1 38.8 1 10.1 1 14 1

Amendment

BAP equivalency iEPA/600/R-93/089).

TCDD toxicity equivalency (USEPA, 1989)

2 kilograms soil (dry weight)

Exhibit 2. Land-Farming Sample Test Protocol (USEPA, 1998)

Nutrients'

Test Condition

2 kilograms soil (dry weight)

1. Biotic

Nutrients plus 1000 mg/kg MnO.,

2. Biotic with MnO,

2 kilograms soil 3. Abiotic' Nutrients plus 2000 mg/kg HgC1,

4. Abiotic with MnO, 2 kilograms soil Nutrients plus 2000 mg/kg HgCl,, 1000 mg/kg MnO,

Nutrients consisted of ammonium nitrate and potassium phosphate to achieve a carbon:phosphorous ratio of 10: 1.

'Abiotic (control) samples were treated with mercuric chloride (HgC1,) to sterilize the soil.

All test soil pans were covered with lids allowing for adequate ventilation, and temperature was maintained between 32 OC and 35 "C. The moisture content was monitored every three days and adjusted to maintain 50 to 80 percent of field capacity. All soils were mixed after water was added to simulate soil tillage in a land farming operation. Samples were collected from each replicate pan and composited into one sample for analysis. Each soil test was conducted for a period of 91 days with treatment samples collected from all test conditions and replicates at intermediate days 21 and 47 with a final posttreatment sample at 71 days. This sampling regimen provided a realistic time interval for the progression of the

70 REMEDIATION/SUMMER 2000


Analytes (ppb)'

anticipated degradation of the target contaminants. These samples were analyzed for TPH. Based upon the TPH results, two optimum test conditions for each of the three soil samples were selected for SVOCs and PCDDs/PCDFs analysis.

Day 0 Initial

Results After 91 days, one sample from each treatment condition was analyzed

for SVOCs (EPA method 8270) and PCDDdPCDFs (EPA method 8290). Not all representative and replicate samples were analyzed due to cost considerations. The sample analyses were intended to offer trends in contaminant response. Results for the two soil types are indicated below.

(1) McCorniick & Baxter (MCB) Soil: Exhibit 3 shows selected results on contaminant response for initial (Day 0) and final (Day 91) samples collected from biotic treatment with and without (w/o) MnO, amendment.

Day 91 Biotic w/o MnO,

Exhibit 3. Results for Select Analytes in the Land-Farming of MCB Soil (LTSEPA, 1998)

Day 91 Biotic with MnO,

Acenaphthene

Fluorene

Phenanthrene

63,000 35,000 27,000

20,000 12,000 11,000

63,000 84,000 55,000

Anthracene I 67,000

~~

Total PAHs'

PCP

152,000

974,000 2,093,100 920,500

290,000 720,000 200,000

I 45,000

TCDD/TEQ3

BAP potency estimate'

11.7 16 13.5

55,129 - 63,934 53,853 - 62,298 45,884 - 52,268

Pyrene I 222,000 I420,OOO I 160,000

I Semivolatile organics by GUMS 8270.

Polynuclear arom:itic hydrocarbons.

TCDD toxicity equivalency quotient by Method 1-TEFS/89.

+ BAP potency estimate calculation (EPA/60O/R-93/089).

REMEDIATION/~UMMER 2000 71


One observed anomaly in the data, especially for samples taken from biotic treatment without amendment, was an increase in final (day 91) contaminant concentrations over the initial (day 0).

The abiotic samples were only analyzed for day 21 and day 47 samples. Five of sixteen priority PAHs analyzed are shown along with Total PAHs, PCP, TCDD/ TEQ, and BAF’ potency estimate. In general, PAH concentrations following biotic treatment with MnO, amendment were lower than those for biotic treatment without the amendment. This supports the premise that manganese can have a positive effect in the biotic oxidation and/or humification of the target contaminants. MnO, is a stable compound that not only serves as a strong oxidizer, but also has the value added benefit of providing enhanced oxygen- ation and contact to help facilitate biodegradation (USEPA, 1777).

One observed anomaly in the data, especially for samples taken from biotic treatment without amendment, was an increase in final (day 91) contaminant concentrations over the initial (day 0). For the biotic without amendment, PCP concentrations, Total PAH, TCDD-TEQ and the BAP potency estimate for the day 91 samples were higher than the initial. Similar increases in contaminant concentrations over treatment time have been observed in other soil treatment tests, which were considered to be the result of increased extractability of a soil/nonaqueous phase liquid (NAPLYwater complex as compared to the initial complex less the water addition (USEPA, 1798). Although this interpretation is subject to further verification, results obtained from these studies are best evaluated by looking at the day 71 comparisons. Data obtained for the TPH determinations were inconclusive.

(2) RAB Valley Soil: Based on day 21 and day 47 TPH results, only the optimum samples (the most TPH reduction) obtained from the four specified test conditions, following 71 days of treatment, were sent to the laboratory for SVOCs and PCDDdPCDFs analysis. Exhibit 4 shows these selected results on contaminant response for abiotic (control) without MnO, amendment and biotic treatment with the amendment. In contrast to the MCB biotic treatment without amendment test, the RAB abiotic control without amendment did not show an increase in extractable PCP at day 71. Furthermore, after 71 days, PCP levels were lower in the RAB biotic treatment with amendment than either the abiotic control without amendment or the day 0 samples. There was no indication of increased extractability of total PAH in the abiotic RAB soil, as compared to the biotic MCB soil samples, showing that the increase in extractability of total PAH in MCB soil may be a result of biosurfactants produced during microbial activity. Results obtained for the TPH determinations were as inconclusive as the MCB treatment samples, with the best result obtained for the abiotic treatment sample with amendment, after 47 days (-67 percent reduction).

Biotreatment Augmented with Fenton’s Reagent Another type of augmentation was evaluated that utilized the oxidizer,

Fenton’s Reagent, which is a formulation of hydrogen peroxide and ferrous sulfate. Fenton’s Reagent generates hydroxyl radicals (EOH), which will provide a strong chemical oxidation of compounds, such as petroleum hydrocarbons and many organic compounds. This reaction (Fenton, 1874) is shown in the following equation:



Analytes (ppb)l Day 0 Day 91 Abiotic Initial w/o MnO,

Anthracene 480,000 570,000

Acenaphthene 88,000 45,000

Fluorene 2 20,000 120,000

Phenanthrene 530,000 390,000

Pyrene 240,000 170,000

Total PAHs’ 2,712,600 2,275,300

PCP 480,000 4 20,000

TCDD/TEQ3 28.4 48.6

BAP potency estimate’ 36.917 - 43,259 39,526 - 46,204

Day 91 Biotic with MnO,

600,000

45,000

140,000

470,000

170,000

2,454,700

360,000

24.3

38,283 - 43,505

Fe(I1) + H,O - - ~ + ferric iron (Fe(II1)) + hydroxide ion (EOH) + OH(1)

The OH that is formed can either react with Fe(II1 to produce Fe(II1) as shown below:

EOH + F d I I ) + Fe(II1) + OH(2)

or react with and initiate oxidation of organic pollutants in aqueous waste streams. It is especially suited for applications using bioslurry reactors.

Experimental Design Pretreatment samples were collected from MCB contaniinated soil and

an ACW water/product emulsion. The experimental design involved the evaluation of five discrete test conditions, as presented in Exhibit 5.



1. Conventional Treatment

2. Fenton’s Treatment

3. Fenton’s plus Ferric Iron

14. Abiotic Control3

Although samples were collected and analyzed during the initial characterization study for both sites, SVOCs (Method 8270) and TPH (Method 413.1) were analyzed on the pretreatment samples in order to establish a current baseline for these parameters (USEPA, 1998). The TPH analysis was conducted on all test samples in order to provide a rapid, inexpensive means of monitoring the treatment progress. The slurries were prepared with proportionate quantities of soil, deionized water, and nutrient formulation (RestoreTM). Nutrient amendment was applied to each treatment by adding 0.04 grams of RestoreTM, a proprietary blend of nutrients consisting of 5 percent ammonium chloride, 20 percent disodium phosphate, 12.5 percent monosodium phosphate, and 12.5 percent sodium tripolyphosphate. No nutrients were added to the abiotic or biotic controls. The abiotic control was prepared by adding 0.4 g of mercuric chloride (HgCl,).

The first three treatment conditions and the biotic control (Exhibit 5)) for both sites, were placed onto a shaker apparatus, operating at a setting of 120 and incubated at 25 “C. The abiotic control was placed in a refrigerator at 4 “C. This was done to inhibit microbial activity. The treatments were sampled after 5, 10, 15, and 30 days for TPH. Four

Slurry with nutrient None

Slurry with nutrient Fenton’s Reagent’

Slurry with nutrient Fenton’s Reagent’ plus ferric iron/EDTA complex

Slurry in deionized water 0.1% HgC1,

Exhibit 5. Fenton’s Reagent Treatability Study (USEPA, 1998)

5. Biotic Control

h t Condition-1 Media

Slurry in deionized water none

I Amendment

Fenton’s Reagent was comprised of 10 millimolar (mM) ferrous ions and 0.5 molar CM) concentration of hydrogen peroxide (H,O,).

’ Fenton’s Reagent was comprised of 10 milliinolar (mM) chelated ferric iron solution and 0.5 molar (M) concentration of hydrogen peroxide (H202>.

Abiotic (control) samples were treated with mercuric chloride (HgC1,j to sterilize the media,


BIOREMEDIATION TREATABILiTY STUDIES OF CONTAMINATED SOILS AT W O O D PRESERVING SITES

As evidenced by the data, the conventional biological and Fenton’s plus ferric iron treatment offered the best treatment of the three test regimes yielding 91 percent and 92 percent reduction in total PAHs, respectively.

replicates of the treatments were taken in order for one replicate to be sacrificed for the TPH analysis. The two controls were only sampled for TPH at the end of the study. The treated samples were also analyzed for SVOCs (Method 8270) and PCDDs/PCDFs (Method 8290) at the end of the study (day 30).

ResuZts Selected TPH, SVOCs, and PCDDdPCDFs measurements are provided

for each of the two respective site treatability test samples (ACW and MCB). Selected analytes. which have been listed on the PBT Chemical List, along with BAP potency estimate and TCDD/TEQ calculations, are presented. Common to both soil matrices, the recorded TPH measurements had shown no declining trend during the study.

(1) Americau Creosote Works Water: Exhibit 6 shows the results obtained from the treatment of the ACW water for the three specified test conditions. SVOC, BAP potency estimate, and TCDD/TEQs are provided. Since the pretreatment sample appeared to be biphasic, samples were mixed prior to analysis with the results reported as pg/L. Due to the higher solids content of the treated samples with the addition of sterile soil, the results were reported as pg/kg. The results were normalized by dividing the pretreatment sample/laboratory result by the specific gravity of the sample and the dilution factor associated with the addition of the amendment material in preparation of the slurry.

As evidenced by the data, the conventional biological and Fenton’s plus ferric iron treatment offered the best treatment of the three test regimes yielding 91 percent and 92 percent reduction in total PAHs, respectively. The Fenton’s treatment resulted in a 78 percent reduction in total PAHs. Similarly, values reported for the BAP potency estimate for conventional biological and Fenton’s plus ferric iron treatment showed a 95 percent and 97 percent reduction, respectively, while Fenton’s treatment resulted in a 93 percent reduction. Dioxidfuran concentrations are expressed in TCDD/TEQ values. The pretreatment sample and the final treatability samples are incongruent for comparative purposes, since the pretreatment water sample was analyzed in two phases (oil and water) with the treated samples mixed for one discrete analysis. The lowest computed TCDD/TEQ value was observed for the biological treatment sample (3.12 TEQ) followed by the Fenton’s plus chelant (3.51 TCDD/TEQ) and then Fenton’s (3.88 TEQ).

(2) McCormick & Baxter Soil: Exhibit 7 shows the results obtained from the treatment of the MCB soil for the three specified test conditions. SVOC, BAP potency estimate, and TCDD/TEQs are provided below. All analytical results were reported on a dry weight basis; thereby, the reported contaminant levels were not influenced by the addition of deionized water in the preparation of the slurry. As indicated by the results, it appeared that most SVOCs including the total PAHs were reduced by at least 50 percent in the conventional biological treatment test. No significant reduction was observed for the Fenton’s Reagent tests with or without the chelant (ferric iron). For the TCDD/TEQ determinations, the computed toxicity was



Normalized

Exhibit 6. Results for Select Analytes in the Fenton’s Treatment of ACW Water (USEPA, 1998)

Concentration (pph) Initial

Fenton’s

4,400

19,000

I Pretreatment 1 Pretreatment I Fenton’s plus Ferric Iron

2,000

9,000

Anthracene

Acenaphthene

Fluorene

Phenanthrene

1 29,594 I 61,000

77,625 160,000 10,000

53,367 110,000 1,200

194,062 400,000 320

I 860

28,000

7,400

188,940

52,000

14,000

2,800

70,418

12,000

Pyrene I 58,217 I 120,000

824-969

I 3,900

360-427

Total PAHs’ I 865,712 I 1,784,400 1 77,964

10,480-12,273

1 77,625 PCP

556-659

I 160,000 I 48,000

TcDDlTEQ?r-- I 459.22 (oil) I 3.12 0.33 (water)

BAP potency estimate’

13,000 1 5,000

3.88 1 3.51

Semivolatilc organics by GUMS 8270.

Polynuclear aromatic hydrocarbons.

’ TCDD toxicity equivalency quotient by Method LTEFS/89

’ RAP potency estimate calculation (EPA/60O/R-93/089).

lowest in the biological treatment when compared to the other two test regimes. Also, PCP was reduced approximately 46 percent via conventional biological treatment. Concentrations obtained for the other two test conditions (Fenton’s and Fenton’s plus chelant) actually exceeded the pretreatment sample. The results from MCB and ACW for biotreatment augmented with Fenton’s Reagent show the success of the treatment is dependent on the soil characteristics.

Induced Biotreatment via Inoculation The third treatability study utilized a cellular bioreactor to treat a

contamiiiated soil saturated with a groundwaterloil emulsion from the



Analytes (p pb)

Anthracene

ACW site. An amendment of proprietary nonpathogenic microorganisnis and nutrient was added to the contaminated soil to facilitate biodegracla- tion. These microorganisms and nutrients were selected from previously conducted field tests based upon pH, dissolved oxygen (DO), cheniical oxygen demand (COD), and biological oxygen demand (BOD) deternii- nations under saturated conditions. Microorganisms and nutrients were applied to the soil and mixed using a hand rake. Two 7-gallon vessels were utilized for the treatability testing. These vessels were shielded from the top to prevent tampering.

Fenton’s plus Ferric Iron Biological Fenton’s

57,000 43,570 58,876 119,718

Pretreat me nt

Experimental Design The experimental design included the collection of initial (day 0) and

final (day 45) samples for SVOC (EPA Method 8270) and PCDDs/PCDFs

Acenaphthene

Fluorene

Phenanthrene

Exhibit 7 . Results for Select Analytes in the Fenton’s Treatment of MCB Soil (USEPA, 1778)

87,000 50,641 67,485 105,634

27,000 12,821 18,405 26,761

75,000 39,103 67,485 70,423

P yrene

Total PAHs‘

180,000 76,154 176,317 274,648

1,627,160 808,835 1,410,368 1,936,901 ~ ~~~~

PCP

TCDD/TEQ’

BAP Equivalency’

460,000 250,000 484,663 584,507

14.23 6.06 7.55 7.13

62,226-7 1,7 15 28,5 14-33,113 48,5 1956,405 65,726-76,74 1

I Sernivolatile organics by GUMS 8270.

’ Polynuclear aromatic hydrocarbons.

TCDD toxicity equivalency quotient hv Method 1-TEFS/89

’ BAP potency estimate calculation (USEPA, 1993).


DOUGLAS W. GROSSE ENDALKACHEW SAHLE-DEMESSIE E ~ w m R BATES

Analytes (ppb)’

BAP potency estimate‘

(EPA Method 8270) analyses. Intermediate treatment samples (days 10, 20, and 30) were collected for SVOC analysis. During the treatability testing, two replicate samples were collected throughout the duration of the study.

Day 0 Day 45” Day 45b

203,245 - 240,414 71,270 - 82,942 54,350-67,270

% Change 65 - 66 7 3 - 71

Results Exhibit 8 shows the BAP potency estimate results obtained from the

treatment of the ACW soil saturated with a groundwater/oil emulsion. In accordance to the experimental design, replicate samples were taken that generated two data sets. Due to the variability of results obtained from the intermediate sample events (days 10, 20 and 301, only initial (day 01 and final (day 45) data are presented for the analytes identified prior. Indications are that BAP potency estimates (dry weight basis) were reduced up to 73 percent after 45 days of treatment. Results obtained for PCDDs/PCDFs and TCDD/TEQ were inconclusive with final sample concentrations actually increasing over the duration of the study.

CASE STUDIES Many case studies and demonstration projects have shown the

successful application of bioremediation technology in treating wood preserving contaminated sites. Bioremediation of contaminated soils and sediments has been accomplished through the use of specially designed treatment systems. Specific applications have used bermed land treatment units, slurry-phased bioreactors, and solid-phased land-farming chambers for the treatment of wood treater contaminants. Information derived from several of these field scale demonstration projects are summarized below.

Case Study 1: Land Treatment Unit The Champion International Superfund site in Libby, Montana, was a

former wood treater’s site that contaminated adjacent private wells. Both



Both soil and groundwater were contaminated with

, PCP and PAHs resulting from the

~ seepage and spillage , of reagents used in the ~ wood preserving operations.

soil and groundwater were Contaminated with PCP and PAHs resulting from the seepage and spillage of reagents used in the wood preserving operations. Wastewater and tank bottom sludge from fluid tanks were periodically removed and hauled to waste lagoons where more soil and groundwater contamination ensued. Left unchecked, the resulting contaminant plume would eventually migrate to the Kootenai River, or Flower and Libby Creeks. Since the Record of Decision (ROD) has been signed, several phases of remediation have been prescribed with one utilizing land treatment units (LTUs) for the bioremediation of contaminated soil (USEPA, 1797).

System Design Two 1-acre bermed LTUs were constructed with leachate collection

systems. Each liner system consisted of 60-mil-high density polyethylene liner (HDPE), compacted clay, geotextile filter fabric, and geonet. A leachate collection system consisted of perforated HDPE piping, gravel drains, and sump. In addition, there was provision for a rainfall runoff/ leachate storage and a passive moisture control system (Huling et al., 1995). The contaminated media were transported and placed into the LTUs in 6- to 12-inch layers (lifts) for treatment during temperate weather (March to October). A new layer (or lift) was added to the LTU when treatment goals were met for the preceding layercs). Either recycled leachate or other makeup water from on-site was added to maintain moisture levels between 40 to 70 percent of field capacity. Nutrients were also added in the form of inorganic nitrogen and phosphorous. Nutrient addition occurred as frequently as eveiy other day. Tilling of the LTUs was conducted on a weekly basis. Previously conducted treatability studies indicated that indigenous microorganisms were able to biodegrade the target contaminants at temperatures and moisture conditions present at the site.

Performance The primary contaminants of concern present at the site were the

carcinogenic PAHs, naphthalene, phenanthrene, pyrene, and PCP. The results of the demonstration project are presented in Exhibits 9 and 10. Two treatment events (lifts 4 and 5) are discussed. The performance data are listed in consecutive days of treatment for each sampling event. Also, no dioxin data were available for inclusion in this data set. Lift 5 was placed on top of lift 4, 80 days after the initial placement of lift 4.

Results from the field demonstration for both lift events indicate that TCPAH, pyrene, and PCP showed significant biodegradation after approximately 50 days. For lift 4, results did not significantly improve after more than one year of treatment (day 482). However, in lift 5, contaminant removal improved significantly over the duration of one year for the same contaminants. Naphthalene and phenanthrene appeared to be the most difficult to degrade for both lifts with the exception of day 135 in lift 4. Further treatment (day 482) actually showed an increase in contaminant concentration in lift 5. Perhaps the incremental addition of lift 5 adversely impacted the rate of biodegradation for these two compounds.

~~



Day 51

Exhibit 9. Mean’ Contaminant Concentrations Lift 4, Champion International (USEPA, 1777)

Day 135 Day 482 Analyte

Naphthalene

Phenanthrene

Pyrene

TCPAH?

PCP

Initial (Day 0)

Conc. (mg/k@

4.5

2.5

76.5

230

132.1

1.7

Conc. (mg/kg)

1.5

0.7

3.7

41.0

10.5

1.0

Percent* Change

-67

-72

-75

-82

-72

4.8

40.1

10.1

PercentZ Change

-62

-60

-74

-83

-9 2

0.2

4.6

33.0

20.7

Percent: Change

-9 1

-92

-94

-86

-84

’ Mean includes one or more non-detects that were averaged in as zeros. I’rrcent change is stated as decrease (-1 or increase (+I. TCPAIl represents the sum of the following carcinogenic PAHs: fluoranthene, pyrene,

benzo(a)anthracene, chrysene, benzo(b)fluoranthene, benzo(k)fluoranthene, henzo(d)pyrene, dibenz(a,h)anthracene, benzo(ghi)perylene, and indeno(l23-cdlpyrene (USEPA, 1997).

cost Construction costs for the two LTUs totaled $400K with nominal

operation and maintenance (O&M) plus monitoring costs estimated to be $117K in 1972. Based upon these constant costs and treatment of 45,000 yd3, the unit treatment cost is estimated to be approximately $35 per yd’ or $27 per ton of contaminated soil. The use of LTUs for treating contaminated soil at wood treater’s sites has gained in popularity and is currently being applied at other sites.

Case Study 2: Slurry-Phase Bioremediation Slurry-phase bioremediation has matured into an established engi-

neered process for remediating wood treater soils and sludge (Woodhull & Jerger, 1794). A Superfund Innovative Technology Evaluation (SITE) demonstration was performed at the USEPAs Test and Evaluation (T&E) Facility in Cincinnati, Ohio, during May through July 1991 (USEPA, 1773a). Creosote-contaminated soil, obtained from the BN Superfund Site in Brainerd, Minnesota, was used in evaluating the slurry-phase technology.

80 REMEDIATION/~UMMER 2000


Analyte

The contaminated soil was a fine, sandy soil, with 75 percent of the soil comprised of grain sizes between 0.1 and 0.4 mm in diameter. The soil also yielded a relatively low moisture content (10 percent) with a heat value below 500 Btu/lb. Total PAH concentrations and heterocyclics ranged from 34,388 (first impoundment) to 134,044 (second impoundment) mg/kg. The contractors were IT Corporation (on-site contractor) in conjunction with the vendor, ECOVA. Some of the key objectives of the technology demonstration, as performed under the SITE program, are as follows: (1) evaluate the ability of the slurry-phase bioreactor to degrade PAHs present in the contaminated soil, (2) evaluate reactor performance and removal efficiencies for treating PAHs and soil toxicity, (3) determine air emissions during biodegradation in the reactor, and (4) develop information on capital and operating costs for the full-scale treatment system.

Initial (Day 0) Day 54 Day 401 Percent2 Percent2

Conc. (mg/kg) Conc. (mg/kg) Change Conc.(mg/kg) Change

System Design Five 64-liter (working volume) EIMCO BioliftTM reactors were used to

demonstrate the slurry-phase technology's capability in degrading soil- bound PAHs. These bioreactors were operated in batch mode for a duration of 12 weeks. Soil contaminated with creosote was homogenized, drummed, and shipped to the T&E Facility. The soil was screened through a one-half inch sieve to remove oversize material and mixed with water to

Phenanthrene

Exhibit 10. Mean' Contaminant Concentrations Lift 5, Champion International (USEPA, 1997)

<0.95 I 0.7 I 1.0 I NC

I 1.0 I -9.1 12.0 I +a2 I 1 Naphthalene I 1.1

I 135 I 35.3 I -74 I 4.3 I -97 I I Pyrene

I 254 I 103 I -59 137.1 I -85 I I TCPAH?

' Mean includes one or more non-detects that were averaged in as zeros.

Percent change is stated as decrease (4 or increase ( + I

TCPAH represents the sum of the following carcinogenic PAHs: fluoranthene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluorantliene, benzo(k)fluoranthene, benzoialpyrene, dibenz(d,h)anthrdcene, benzoc ghiipeiylene, and indeno(l23-cd)pyrene (USEPA. 1997).



form a 30 percent slurry. The slurry was further milled in a ball mill and screened at exit through a No. 8 sieve to produce a slurry with the corresponding particle grain size. The demonstration was initiated with the placement of 66 L of slurry into each of five bioreactors. Thereafter, a concentrated inoculum of indigenous bacteria was added to each of the five reactors. To further stimulate biological activity, nutrient amendment, consisting of ammonia, phosphate, magnesium, calcium, iron, and ammonium molybdate, was added to each bioreactor. Sampling and analysis activities were performed over the duration of the demonstration project, which involved collecting composite samples from each of the five reactors for pre- and posttreatment analyses. During the study (12 weeks), soil-bound and liquid-phase PAHs, TPHs, pH, DO, temperature, toxicity, and microbial activity were monitored. In the ninth week of operation, four of the five bioreactors were recharged with an additional dose of inoculum to stimulate microbial activity.

Performance Results from this demonstration project showed significant reduction

of PAH concentrations in the soil matrix for 2- and 3-ring, 4- through 6-ring, and Total PAHs. Exhibit 11 provides concentrations and percent removal data for Total PAHs during week nine and week twelve sampling events. Indications are that greater than 87 percent of Total PAHs were removed over all five operating reactors after 12 weeks of demonstration. Air samples taken continuously during the first five days and periodically thereafter, have shown that volatilization of organics was initially significant but diminished to below detection limits after five days of operation. MicrotoxTM analysis, over the course of the study, showed significant decrease during the slurry-phase biological treatment process.

Results from this demonstration project showed significant reduction of PAH concentrations in the soil matrix for 2- and 3-ring, 4- through 6- ring, and Total PAHs.

cost The cost of slurry-phase bioremediation is very site-specific with labor

costs associated with materials handling and operation accounting for more than half of the incurred costs. Estimated costs for the SITE demonstration project, which include capital equipment, start-up, labor, utilities, maintenance, consumables, and disposal, range from $294/yd3(based upon 275 m3 reactor) to $145/yd3 (based upon a 1,125 m3 reactor). In another demonstration project, conducted on the slurry-phase bioremediation of 1 million gallons of refinery waste, costs were calculated to be $50.5/yd3 (USEPA, 1993a). Like most remediation technologies, it can be concluded that an economy of scale exists for treating larger quantities of contaminated media.

CONCLUSIONS Treatability studies performed under the NRMRL Remedial Treatability

Study Assistance Program have shown that the use of amendments such as MnO,, Fenton’s Reagent and ferric iron complex can have a beneficial impact in bioremediating contaminated media at wood treater sites. These amendments were selected exclusively by the performing vendors in their

82 REMEDIATION/SUMMER 2 0 0 0

BIOREMEDIATION TREATABILITY STUDIES OF CONTAMINATED SOILS AT W O O D PRESERVING SITES

Bioreactors Week 0 Percent

Conc. (mg/kg) Removal

Reactor 1 3709 NA

Reactor 2 2193 NA

Reactor 4 678.5 NA

Reactor 5 4480 NA

Exhibit 11. Concentrations and Percent Reinovals of Total PAH Levels in Soil Samples' (USEPA, 1993a)

Week

Conc.(mg/kg)

<305.1

<70.7

<390.2

~ 3 4 0 . 4

I Reactor6 I 1220.6 I NA I 200.3

9 Week 12 Percent Percent Removal Conc.(mg/kg) Removal

>91.77 <365.9 >90.10

>96.77 <291.3 >86.72

>42.50 <99.4 X35.35

>92.40 <450.9 x39.94

83.59 <336.5 >72.43

308.8

' All the PAH analyses were performed by GUMS Inethod (SW-846. Method 8270)

attempt to maximize performance objectives. MnO, was used to provide the additional benefit of having a strong oxidizing reagent work in tandem with biodegradation. Fenton's Reagent was used similarly with the added benefit of generating powerful hydroxyl radicals. Oily (creosote/hydrocarbon) matrices and/or substrates are known to scavenge hydroxyl radicals that can be remedied by adding excess ferric iron complex. Conversely, results obtained for the inoculated biotreatment of soil/water emulsions were inconclusive. However, BAP potency estimates showed reductions ranging from 65 to 73 percent following 45 days of treatment. Case studies evaluating land-farming applications at the Champion International Superfund Site have shown significant PCP (>86 percent) and TCPAH (>82 percent) reduction in the field. Similarly, percent removal calculations for total PAHs obtained from pilot-scale bioslurry treatability studies have shown reductions in total PAH ranging from 72 to 90 percent for all five reactors in seivice. Since most of the constituents analyzed during the treatability studies were not considered to be volatile, volatilization effects were largely considered to be demirzimus. Neither time nor budget allowed for a complete mass balance determination. Although variability in sampling, analysis, and matrix effects can produce inconclusive results for these types of studies, sufficient information has been obtained to indicate that hioremediation can offer a low-cost alternative to achieve performance-based objectives in remediating wood treater sites.

REMEDIATION/SUMMER 2 0 0 0 83


REFERENCES Fenton, H.J.H. (1894). Oxidation of tartaric acid in the presence of iron. JoLirndl of thc Chemical Society, 899.

Huling, S.G., Pope, D.F., Mathews, J.E., Sinis, J.L., Sims, R.C., B Sorensen, D.L. (1995). Land treatment and the toxicity response of soil contaminated with wood preserving waste. New York: John Wiley & Sons, Inc.

United States Environmental Protection Agency. (1989, March). Interim procedures for estimating risks associated with exposures to mixtures of chlorinated dibenzo-p-dioxins and dibenzofurans (CDDs and CDFs) and 1989 update (EPA/625/3-89/016).

United States Environmental Protection Agency. (1993a, January). Pilot-scale demonstration of a slurry-phase biological reactor for creosote-contaminated soil (Applications Analysis Report EPA/540/A5-91/009).

United States Environmental Protection Agency. ( 1993b, July) Provisional guidance for quantitative risk assessment of polycyclic aromatic hydrocarbons (EPA/600/R-93/089).

United States Environmental Protection Agency. (1997, October). Treatment technology performance and cost data for remediation of wood preserving sites (EPA/625/R-97/009). Cincinnati, OH: Center for Environmental Research Information, National Risk Management Research Laboratory, U.S. EPA.

United States Environmental Protection Agency. (1998, November). Environmental fact sheet (EPA/530-F-98-028). Office of Solid Waste and Emergency Response.

Whitford, K.. Krietemeyer, S., Tillman, J., M- Wahl, G. (1998, February). Treatability studies for wood preserving sites, a compilation of treatability studies performed under contract by IT Corporation (CN 68-CZ-0108) and SAIC (CN 68-C5-0001), (EPA 600/R-98/0260), NTIS PB98-132400.

Woodhull, P.M., & Jerger, D.E. (1994, Summer). Bioreniediation using a commercial slurry- phase biological treatment system: Site-specific applications and costs. Rernediation Journal, 353-363.


bioremediation treatability studies of contaminated soils at wood preserving sites

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