CICEET Progress Report for the period 3/16/06 Through 9/15/06

Project Title: In Situ Sediment Ozonator for Remediation of PCB, PAH, DDT and Other Recalcitrant Chemicals
Principal Investigator(s): Andy Hong, Ph.D., P.E.
Additional Investigator(s): Don Hayes, Ph.D., P.E.
Project Start Date: September 1, 2004

Figures

Figure 1

Figure 2

Equipment
What admixtures can be added to sediments to provide physical stability when re-deposited in-situ by ISO?
Do Atterberg Limits correlate with sediment stability?

Reports and Publications

Tasks to meet objectives
The process parameters have been studied and a large part of the results have been submitted in the earlier reports. This period has focused on replicating and confirming results obtained previously. The studied parameters include ozonation time, ozone concentration and dose, and incubation time with microorganisms to achieve maximum degradation of PCB, PAH and DDT.

Based on the results, replicates, and other needed confirmatory experimental results, we have drafted 5 papers and they are at the final stages of being submitted to journals for review and publications. The abstracts of these individual papers are included at the end of this report (Appendix A).

An experimental plan was developed and executed for testing the effect of admixtures on sediment’s physical stability. Admixtures include Bentonite, Kaolin, Sand, Lime, and combinations of these.

A SEDFlume was constructed to test the relative erodability of amended sediment mixtures

Amended sediments were tested in the SED Flume and the relative erosion rates documented.

The Atterberg Limits were tested for various sediment batches.

Four additional conference abstracts were submitted based on the process and equipment results for presentations in 2007.

Progress on Tasks
All the above tasks were completed.

Have the results/data gathered during this reporting period changed the project objectives when compared to your original proposal?
The results gathered were useful in evaluating possible approaches to stabilize treated sediments before replacing them on the bottom, which was our original objective for this effort. For example, we learned that clay is an important ingredient in reducing erosion because it increased the plastic limit. In contrast, increasing sediment density by adding dry sand still allowed fine particles to be eroded from between the sand grains.

Dissemination activities during this reporting period
Publications (6-7 participants including the PIs and students on the project):
Hua Xu. Ph.D. Dissertation, “Integrated Chemical-Biological Treatment of PCB and DDT” University of Utah

H. Xu; A. Hong; D. Hayes. “Integrated chemical-biological treatment of PCBs and PAHs in sediment of Waukegan Harbor.” In preparation for submission.

H. Xu; T. Datta; A. Hong; D. Hayes “Integrated chemical-biological treatment of DDT in organic and aqueous phases and in spiked sediment.” In preparation for submission.

H. Xu; A. Hong; D. Hayes. “Kinetics and mechanisms of ozonation of Aroclor 1260 and decachlorobiphenyl in carbon tetrachloride.” In preparation for submission.

H. Xu; Z. Cha, A. Hong; D. Hayes “Integrated chemical-biological treatment of PCBs in Aroclor 1242-spiked sediment slurries.” In preparation for submission.

H. Xu; A. Hong; D. Hayes. “Reaction Kinetics and products of Aroclor 1242 congeners with ozone in carbon tetrachloride solution.” In revision.

Conferences:
Z. Cha; H. Xu; A. Hong; D. Hayes “Degradation by Ozonation of PCBs in Spiked Sediment,” The 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, March 13-16, 2006, San Diego, CA.

H. Xu; A. Hong; D. Hayes “Chemical-Biological Treatment of PCBs in Sediment of Waukegan Harbor,” The 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, March 13-16, 2006, San Diego, CA.

A. Hong; H. Xu; D. Hayes “Reaction Kinetics and Products of Aroclor Congeners with Ozone,” The 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, March 13-16, 2006, San Diego, CA.

T. Datta; H. Xu; A. Hong; D. Hayes “Chemical Treatment of DDT in Organic and Aqueous Phases and Biological Incubation,” the 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, March 13-16, 2006, San Diego, CA.

S. Nakra; A. Hong; D. Hayes “Degradation of PAH contaminants in St. Louis River Sediment with Chemical-Biological Treatment,” The 16th Annual AEHS Meeting & West Coast Conference on Soils, Sediments, and Water, March 13-16, 2006, San Diego, CA.

A. Hong, H. Xu, D. Hayes “In Situ Chemical-Biological Treatment of PCB-Contaminated Sediment,” 15th Annual AEHS Meeting and West Coast Conference on Soils, Sediments, and Water, March 14-17, 2005, San Diego, CA.

D. Hayes and A. Hong “Innovative concept for in situ contaminated sediment remediation,” Western Dredging Association (WEDA) 2004 conference, July, Orlando, Florida.

Degradation of PCB and PAH in Waukegan Harbor Sediment. Andy Hong, Shamit Nakra, and Don Hayes. 17th Annual West Coast Conference on Soils, Sediments and Water, March 19-22, 2007 in San Diego, CA. Submitted

Degradation of MTBE by Ozone and Hydrogen Peroxide. Andy Hong, Han Yu, Don Hayes. 17th Annual West Coast Conference on Soils, Sediments and Water, March 19-22, 2007 in San Diego, CA. Submitted

Degradation of PCB and PAH in contaminated Sediments. Andy Hong, Shamit Nakra, and Don Hayes. 2007 Battelle Conference. Submitted.

Innovative Approach to In situ Sediment Remediation. Don Hayes, and Andy Hong. 2007 Battelle Conference. Submitted.

Patent, Copyright, Invention Disclosure Activity:
Hong, Hayes, In Situ Sediment Ozonator for Contaminants Remediation. US Patent No. 7,011,749 B2

Difficulties
At range of shear stresses that was obtainable using a SED Flume, many of the sediment/admixture combinations exhibited either very high or very low erosion rates. Despite this limitation, bentonite clay was identified as a good candidate for sediment stabilization. In comparison with other admixtures, a minimal amount of bentonite clay is required to achieve significant stabilization (reduction of erosion rate).

Data Generated to date

Testing of Admixtures for Effects on Sediment Stabilization
Procedures:
Sediment collected from Great Salt Lake vicinity was diluted to 50%, 40%, 30%, and 20% solids (w/w).

Sand, kaolinite, bentonite, a 50:50 mix of sand and bentonite, 50:50 mix of sand and kaolinite, a 50:50 kaolinite-bentonite mixture and lime were used as sediment admixtures

For the first round of testing, each admixture was added separately to an array of sediments at 40%, 30%, and 20% solids densities to achieve in-situ density (50%). These samples were then tested in the SedFlume at a flowrate of 40 GPM (corresponds to a shear stress of 3.2 Pa). The relative erosion rate of each sample was recorded.

In the second round of testing, sediments at 20% solids were amended with sufficient admixture to achieve a range of final densities (60%, 50%, 40%, 30%, and 20%). These samples were again tested for their relative rate of erosion at 40 GPM (corresponding shear stress of 3.2 Pa).

In the final round of testing, sediments at 20% solids were amended with sufficient admixture to achieve a range of final densities (40%, 30%, and 20%). Rather than testing sediment erosion rates at a constant flow rate (and resultant shear stress) samples were subjected to a range of flow rates. The objective of this test was to determine for each sample an incipient shear stress at which erosion occurred.

Atterberg Limits were performed as per ASTM methods.

Results and Conclusions:
Figure 1 illustrates the effect of increasing proportion of admixtures (kaolin and bentonite) to diluted sediment.
Figure 2 illustrates an attempt to compare the incipient point of erosion for sediments amended with either kaolin, bentonite, or lime.

Despite modifications to the SED Flume and procedures, sediments created as described generally exhibited one of two characteristics. Sediment was either (1) very stable, eroding at immeasurably slow rates over long periods of time or (2) very unstable, eroding at immeasurably high rates over short periods of time.

It was observed that increasing kaolin and bentonite proportions decreased sediment erosion rates. It was also observed that bentonite provides effective stability at much lower proportions than Kaolin. Bentonite again proved to be the most effective admixture. Attempts to directly correlate Atterberg Limits and sediment erodability were unsuccessful, although increasing the plastic limit did tend to decrease erodability.

Project Objectives for Next Reporting Period

Objectives
In the next 6 months during the no-cost extension period, we will continue on finalizing various articles for publications as well as repeating and performing the remaining confirmatory and other needed experiments that would enhance the quality these papers. We will be reporting our additional efforts and results, as well as on the progress of journal publications and conference presentations.

Expenditures
Our expenditures are within the proposed range, and will be expended within the no-cost extension period before August 31, 2007.

APPENDIX A.
Abstracts of journal articles in various stages of revision and preparation. (The Project PIs request that these abstracts be posted on the Web and made publicly available after acceptance or scheduled prints/releases by the journals. We will provide updates as soon as decisions on these articles are available.)

The abstracts of five planned publications are as follows:

1. TITLE: REACTION KINETICS AND PRODUCTS OF AROCLOR 1242 CONGENERS WITH OZONE IN CARBON TETRACHLORIDE SOLUTION
Abstract:
The degradation of Aroclor 1242 was carried out by ozonation in CCl4 solution. All PCB congeners and any formed intermediates from an initial 1,000 mg/L Aroclor 1242 were completely degraded within 20 min. The individual congeners were identified, quantified, and tracked during ozonation; the concentration profiles were used to calculate kinetic rate constants. The second-order rate constants of dichlorobiphenyls, trichlorobiphenyls, tetrachlorobiphenyls, and pentachlorobiphenyls with ozone were found in this work to be 5.0, 2.5, 1.7, 1.1 M-1 s-1, respectively, decreasing with increasing chlorine substitution. The degradation pathway was found to be consistent with that from electrophilic attack by ozone, as well as free radical reactions. The results suggest that PCBs are readily degradable by ozone, despite their well-known persistence in the environment, such as in sediment. The persistence is due to limited access of a physical nature, such as solubility or physical entrapment by the sediment; therefore, remediation efforts for PCBs should be directed toward increasing the exposure.

2. TITLE: KINETICS AND MECHANISMS OF OZONATION OF AROCLOR 1260 AND DECACHLOROBIPHENYL IN CARBON TETRACHLORIDE
Abstract:
Ozonation of highly chlorinated PCB congeners within the product Aroclor 1260 and decachlorobiphenyl were carried out in CCl4 solution. The reaction kinetics of Aroclor 1260 with ozone was studied and intermediates and products of reaction were identified. The reaction of Aroclor 1260 with ozone in CCl4 solution demonstrated a first reaction order with respect to PCB congener concentration. The reaction rate of PCB congeners with ozone decreases with increasing chlorine substitution. Chlorobenzene, chloro 2, 5-furandione, and chlorobezoyl chloride were detected as major products. Both mechanisms involving direct ozone attack and free radical reactions have been proposed to explain the pathways of reaction of PCBs with ozone in homogeneous CCl4 solution.

3. TITLE: INTEGRATED CHEMICAL AND BIOLOGICAL TREATMENT OF PCBS IN AROCLOR 1242 SPIKED SEDIMENT SLURRIES
Abstract:
Polychlorinated biphenyls (PCBs) are persistent, bioaccumulative and toxic compounds (PBTs) targeted by U.S. EPA. The contamination of sediment by PCBs is a significant national and international concern. Ozonation is a more practical and effective method to treat PCBs compared with any other in situ sediment remediation technologies due to its low temperature and pressure requirements. The resultant intermediates and byproducts of ozonation are more water-soluble and biodegradable. In this study, an integrated chemical-biological treatment of PCBs was investigated in Aroclor 1242 spiked sediment. The objectives were to optimize the chemical process to obtain the maximum degradation of PCBs with less time and lower cost, evaluate the biodegradability of sediment after ozonation, and examine the feasibility of the integrated chemical-biological treatment of PCBs in spiked sediment. The results show that the use of ultrasound and acetic acid can significantly enhance the degradation of PCBs in the sediment slurries during ozonation. With 10% (by volume) of added acetic acid, 30 min of ozonation and simultaneous ultrasonic irradiation (20 kHz, 5 sec intervals), PCBs can be completely removed from the spiked sediment. Further treatment of spiked sediment was performed using integrated chemical-biological treatment by addition of microorganisms to the ozonated samples. The ozonated sediment without acetic acid incubated with microorganisms for 1 month at 30 °C, an addition of 95% biodegradation of PCBs in the sediment was obtained. Using the above study the optimized treatment process to degrade the PCBs in sediment was presented.

4. TITLE: INTEGRATED CHEMICAL AND BIOLOGICAL TREATMENT FOR PCBS AND PAHS IN SEDIMENT OF WAUKEGAN HARBOR
Abstract:
Polychlorinated Biphenyls (PCBs) and Polycyclic Aromatic Hydrocarbons (PAHs) are persistent, bioaccumulative and toxic compounds (PBTs). The contamination of sediment by PCBs and PAHs is a significant environmental concern. In this study, an integrated chemical and biological treatment scheme for PCBs and PAHs in the contaminated sediment of Waukegan Harbor was investigated. The primary objectives were to optimize the chemical process which includes ozonation time, the use of ultrasonic irradiation and acetic acid, evaluate the biodegradability of sediment contaminants after ozonation, and assess the feasibility of the integrated chemical-biological treatment scheme for a real-world PCB-and PAH-contaminated sediment. The treated sediment was dried by vacuum filtration, followed by Soxhlet extraction and cleanup procedures according to EPA methods before quantification by gas chromatography/mass spectrometry (GC/MS). The highest degradation level of PCBs and PAHs in the sediment samples was achieved by ozonation of the sediment in a slurry form aided with ultrasonic irradiation and with 10% (v/v) of added acetic acid. After 6 hrs of treatment, more than 90% of PCBs and 97% PAHs were removed from contaminated sediment samples. Biological incubation for 35 days at 30 ºC can remove an additional 56% of PCBs and 68% of PAHs from the sediment that were already treated with ozone for 1 hr in the absence of acetic acid. The results illustrate that the integrated chemical and biological process is potentially more effective than either one alone.

5. TITLE: INTEGRATED CHEMICAL AND BIOLOGICAL TREATMENT OF DDT ORGANIC AND AQUEOUS PHASES AND IN SPIKED SEDIMENT
Abstract:
This study aimed to develop a feasible technology for the degradation of DDT in organic and aqueous phase, by treatment with ozone. The second-order kinetic rate constant for the reaction of DDT with ozone in organic phase was found to be 4.8 M-1 s-1. Possible pathways for free radical reactions taking place during ozonation of DDT in organic phase were proposed. To investigate the degradation of DDT in aqueous phase with ozone, a column reactor packed with glass beads was used. At the loading of 50 mg DDT, a degradation level of 52% was achieved with 1-hr ozonation in the aqueous phase. Percentage degradations at various reaction times and for different DDT loadings were assayed and reported. Effluents obtained from ozonation were subjected to biological treatment. An incubation for a period of 12 days with microorganisms resulted in the complete degradation of DDT in the effluent. Ozonation of DDT-spiked sediment was also performed, which resulted to 54% degradation within 2-hr reaction time.