Project Title: Development of Beneficial Use Alternatives for the Management of Dredged, Contaminated Sediments
Principal Investigator(s): Kevin H. Gardner

Accomplishments
Scheduled Tasks:
The long term goal of this project is to beneficially use contaminated dredged sediments as partial feedstock materials to manufacture Portland cement. This includes characterizing the phases of the heavy metal contaminants in New York/New Jersey Harbor (NY/NJ) sediment, standard portland cement, cement produced with dredged material (DM), and the concrete product from DM-cement. An assessment of As, Cu, Cd, Cr, Pb, Mg, and Zn leachability characteristics will be determined to compare risks associated with these four materials. Understanding both the contaminant phases and their leaching characteristics will verify the environmental feasibility of replacing a portion of raw feedstock material used to manufacture cement with contaminated DM.

The tasks scheduled for this portion of the research project are as follows:

• Execute a full qualitative analysis of the dredged material samples as collected from the NY/NJ harbor;
• Execute a full qualitative analysis of each of the individual feedstock materials as collected from Blue Circle Cement's Ravena plant;
• Evaluate the range of dredged material dosages that can practically be used in cement manufacture;
• Recreate feedstock material slurry using dredged material dosages covering permissible range;
• Commence Portland cement manufacture at laboratory-scale using muffle furnace.

Progress on Tasks
The graduate students working on this project, Jennifer Dalton and Mindy Weimer, continue to review literature sources relevant to this topic within their respective areas of study. As a structural/materials student in civil engineering, Jennifer has been focusing on the manufacture of Portland cement, particularly at the laboratory-scale, and the use of waste and alternative materials in this manufacturing process. Meanwhile, Mindy, an environmental engineering student, has been concentrating on literature sources related to the fate of contaminants - particularly those typically found in dredged sediments - during high temperature processes such cement manufacture.

The three dredged material samples (designated DM A, B, and C) collected from the NY/NJ harbor in the area of the Harlem River were analyzed using x-ray fluorescence (XRF) for the concentrations of oxides important to portland cement manufacture.. Blue Circle cement carried out this analysis in their Ravena, NY plant. The results of this analysis can be found Table 1. Also included are the typical oxide concentrations of Blue Circle's "slurry", which is the raw feedstock mixture that is fired in the kiln to make portland cement.

As shown in Table 1, the dredged material samples contain large quantities of silicon, iron and aluminum oxides, three of the four main ingredients in portland cement. Using the results of typical oxide concentrations and a proportioning spreadsheet has been developed to meet the goals of this project, it was found that as much as 12% dredged material could be used. This, however, assumes adequate reduction of the chlorides inherently present in the dredged material. Total chloride concentration in raw feedstock materials has arisen as a significant issue that we are addressing. Free chloride in Portland cement is restricted to around 0.01% by mass. Although this is likely not to be a problem, as chlorides will be volatilized in the kiln, chlorides can also cause operational problems due to volatilization and scale formation on the kiln walls. Unfortunately, there is not much information available in the literature on this problem. The possible scenarios that are being investigated are: 1. limit the amount of dredged material that can be added in the feedstock, 2. chemical addition to force chloride volatilization at very low temperatures, 3. dewatering and rinsing of sediment to reduce chloride concentration.

The manufacture of portland cement at the laboratory scale using a muffle furnace has begun. The first step has been to quantify the free lime (CaO) in the fresh portland cement clinker samples. The presence of free lime must be minimized as it can lead to expansion of the cement during the hydration process. Free lime content is being used to determine the appropriate program to use for the muffle furnace - specifically the maximum temperature and holding time to use.

Results anticipated for total elemental analysis using Neutron Activation Analysis (NAA) have still not been received from Cornell°s Ward Center. A new set of samples were sent to Cornell in late July.

To further characterize the sediment, Total Organic Carbon (TOC) content was measured. Resulting data from the TOC test is included in Table 2. Sediment A, B and C were taken from different locations in the Harlem River of NY/NJ Harbor. Additionally, metal concentrations of sediment sample leachates were analyzed using Inductively Coupled Plasma (ICP) after leaching in 1M HNO3 for 24 hours (see Table 3). Metal concentrations were also assessed (found in Table 4) after 1 hour of leaching at pH 4. The leaching tests were conducted to quantify amounts of heavy metals typically available to the environment (in contrast to total element concentrations as determined by NAA or total acid digestion).

The equilibrium kinetics of heavy metal leaching from dredged material were investigated to determine a suitable period needed to conduct the remainder of the leaching tests. Concentrations of heavy metals over time were determined using ICP to analyze the filtered leachate from samples taken at 6 hour intervals for 48 hours. Results were graphed to illustrate significant contaminant leaching is completed within 48 hours. One example of such a graph is given in Figure 1.

Acid digestion of the NY/NJ sediment, standard Portland cement, cement produced with DM, and the concrete product from DM-cement are in progress. The latter two materials have not yet been produced, however, some preliminary data for copper and lead leaching from dredged material and Portland cement are included in Table 5.

Dissemination Activities
A poster titled "Beneficial Use of Contaminated Dredged Materials in Portland Cement Manufacture for Sustainable Resource Management" which they presented on June 16-19, 2001 at Clarkson Univeristy's Symposium on Sustainability. The two will also present their work in an oral presentation at the Recycled Material Resource Center's "Beneficial Use of Recycled Materials in Transportation Applications," to be held in Washington D.C. on November 13-15, 2001. Bryan Magee will also give a presentation at the International Conference on Remediation of Contaminated Sediments in Venice, Italy on October 10-12, 2001. An abstract has also been submitted to the Key Technologies for Global Prosperity conference in Orlando, FL, May 2-5, 2002.

Difficulties Encountered
High chloride content in the dredged material has been identified as a major factor influencing the feasibility of this approach to dredged material management. Hence, bench-scale rinsing treatments have been studied to show removal effects. Treatment results have been tabulated below in Table 6. The effect of pH change on the chloride content was also examined using ion-selective electrodes. These results are shown in Table 7. Promising economical technologies such as electrochemical remediation and matrix modification will be considered if chloride proves to be a limiting issue.

Anticipated Success in Meeting Project Objectives in Scheduled Project Period
It is anticipated that the project objectives will be met in the scheduled project period.

Tasks and activities for next reporting period

Tasks for the next reporting period
Leaching characteristics will be investigated through pH-stat testing. These tests are conducted using an automatic titrator that keeps a certain sediment sample at a constant pH for a given amount of time. The testing time was determined by conducting a kinetics experiment to ensure equilibrium concentrations were reached. The leachates gathered from the pH-stat tests will be examined using an Atomic Absorption Spectrometer (AAS). Knowing how contaminant concentrations vary with pH, a better understanding of the phases of the contaminants may be reached. In turn, diffusion rates will be determined both experimentally and theoretically.

Acid digestion procedures will also be completed to approximate the total contaminant content of each material previously mentioned. The gathered information will combined with the leaching results to support assessments of human and environmental risks.

Portland cement manufacture at bench-scale in laboratory will be completed, and evaluation of Portland cement clinker samples will be investigated for performance including physical properties (x-ray diffraction for phase analysis) and contaminant fate. Finally, this work should provide the appropriate parameterization of commencement of Portland cement manufacture at the pilot-scale using a rotary kiln.

Work plan to accomplish tasks
The work plan is envisioned to proceed according to the original proposal. One significant change has been identification of chloride as a major concern. Experiments to investigate the impact of high chlorides will be incorporated into the next phase of research. We will be investigating the fate of chlorides from DM in the furnace, and how chloride fate can be modified by chemical complexation or by removal of chlorides as a pre-treatment step.

Concerns or difficulties
No potential concerns or difficulties are predicted at this time.

Expenditures
Expenditures at this time are in the range anticipated for the work accomplished to date. The most recent accounting shows that 49% of the money has been spent at the one-year mark of the grant.