Marty Tittlebaum

Immobilization of As, Cd, Cr and PB-containing soils by using cement or pozzolanic fixing agents☆

The present work reports leaching data for a soil contaminated with four inorganic model wastes, Cd (II) and Pb (II) nitrates, sodium arsenite, and sodium chromate, at concentrations in the range of 10,000 to 12,200 ppm. Various combinations of Type I portland cement (OPC), Type F fly-ash, blast furnace slag, lime, and silica fume have been used to treat the contaminated soils, which are then leached using a slightly modified EP Tox1 leaching procedure. In no case does fly ash improve performance when mixed with other binding agents. Slag offers superior performance compared to fly ash in any combination tested and has some potential for general utility in practice. In particular, several mixtures including slag are effective in immobilizing lead, which sometimes given problems in solidification with cement. Type I portland is a very versatile and dependable reagent compared to the other agents used. In the cases of As and Cr, the performance of portland alone is superior to that of any other reagent or combination, when comparisons were made at the same dosage level. Cement alone was not among the fixing agents tested for Cd and Pb, but several combinations with cement were included. In every case, inclusion of OPC results in leachate concentrations as low as or lower than the corresponding mixture without OPC.

Solidification/stabilization of arsenic salts: Effects of long cure times

Abstract Leachability of As III and As V from various solidification-stabilization ( S S ) binders has been studied over a period of four years. Type I portland cement (OPC), both alone and mixed with a number of additives, results in toxicity characteristic leaching procedure (TCLP) leachabilities of ≤ 3 mg l −1 for arsenite and ≤ 2 mg l −1 for arsenate. There is no appreciable change in leachability after 3 years of cure, compared with 28 days of cure. The combination of OPC and Class F fly ash as a binder results in substantially degraded performance, as measured by TCLP leachability. Furthermore, the OPC-FA-As mixtures show increasing leachability with time. These solidified products have been studied using powder X-ray diffraction (XRD), derivative thermal gravimetry (DTG) and solid-state magic angle spinning nuclear magnetic resonance spectroscopy (MAS-NMR). The As V salt, NaCaAsO 4 · 7.5H 2 O, is identifiable by XRD in many of these samples, particularly when sodium arsenate is the model As waste, but even when sodium arsenite is the original form of As. The OPC-FA mixtures show substantial respeciation during long curing times. There is evidence for formation of stratlingite from XRD, and there is substantial conversion of octahedrally coordinated aluminum, which is the predominant form at 28 days, to tetrahedrally coordinated aluminum at longer cure times, as shown by NMR. These matrix changes are correlated with increased leachability, although direct cause and effect cannot be established. These results emphasize the importance of long-term testing to identify specific combinations of S S binders and wastes that are prone to undergo respeciation, and consequent leachability changes, after long cure times.

State of the art on stabilization of hazardous organic liquid wastes and sludges

The principal motivation for undertaking this study was to examine stabilization techniques to determine the technical feasilibity of stabilizing/solidifying organic liquid wastes and sludges. The performance of the processes must often be judged on the basis of the manufacturers claims rather than the evaluation of an impartial referee. The study was largely concerned with documenting the state‐of‐the‐art and identifying promising directions for additional research. The most recent available literature, supplemented by telephone contacts with vendors and companies, were the primary information sources. Based on an exhaustive search of the research literature dealing with the solidification and stabilization of hazardous organic wastes, the following observations can be made: (1) Few adequately documented studies have been reported on the performance (physical and chemical stability) of solidified and/or stabilized mixtures containing hazardous organic wastes. (2) Almost no published information exists o...

The effect of sodium sulfate on solidification/stabilization of a synthetic electroplating sludge in cementitious binders

Abstract The effect of sodium sulfate on the solidification/stabilization of a large quantity of a synthetic electroplating sludge in cementitious binders was s

Chemical characteristics of selected flyash leachates

Abstract The physical characteristics of selected flyashes and the quantity of leachate generated from those ashes are evaluated in order to provide the data base needed to develop an environmentally safe disposal management strategy. Ash samples from three sources (1) Clinch River Power Plant at Carbo, Virginia; (2) John Amos Power Plant at St. Albans, West Virginia; and (3) a “Standard” flyash from the National Bureau of Standards were examined. These samples were leached with water according to ASTM extraction procedures and then the leachates were analyzed to determine the total filterable residue, hardness, calcium, sulfate and phosphate concentrations, acidity/alkalinity, and pH. Trace element concentrations were determined by atomic absorption spectrophotometry. Total filterable residue values for the five leachates studied ranged from 180 mg/1 to 1743 mg/1; hardness ranged from 176 mg/1 to 985 mg/1 (as CaCO,), with calcium concentrations ranging from 69 mg/1 to 310 mg/1; and sulfate concentrations...

Evaluation of the leaching properties of solidified heavy metal wastes

Abstract The effects of three inorganic materials on the leaching properties of Type I Portland cement solidification matrix were studied. Also, possible effects on the cement chemistry were suggested. Cadnium nitrate and hydroxide sludges of cadmium and lead were used as the inorganic materials. Cure times of i, 7, and 28 days were studied. Leachability effects were determined by the Toxicity Characteristic Leaching Procedure (TCLP). Hydroxide sludges were added in hydroxide to cement weight percentages of 10% and 30%. A control group containing no additives were also prepared. A control group containing only hydroxide sludges was also tested by the TCLP to determine the amount of metal leached from the sludges alone. Cadmium (Cd+2), in hydroxide or nitrate form, was found by leaching results to be well contained in the cement matrix. All of the TCLP leaching results for Cd+2 were well below the 1.0 mg/L guideline established in the procedure. Lead (Pb+2) was found not to be readily contained as was seen...

Organic interference of solidified/stabilized hazardous wastes

Liquid hazardous waste disposal in landfills is usually allowed only after solidification/stabilization. Although various procedures are commonly practiced, little is known about the mechanism(s) of the processes. A particular problem is the interference of organics. Small amounts of organics can interfere with the reaction between inorganic sludges and cementitous matrices. The present communication reports studies of the interaction between selected organic hazardous wastes and Type I Portland cement. Microscopic studies of the structural differences between cements set with water and those set with water plus organic liquids are discussed. In these studies the scanning electron microscope is used to observe samples fractured at 78K. The results provide technical background data on the ultimate stability of critical waste constituents solidified by various binding agents.

Scanning electron microscopy/energy dispersive X-ray analysis of type I portland cement pastes containing parachlorophenol

Abstract Four mixtures of Type I Portland Cement, parachlorophenol (pCP) and water were examined by scanning electron microscopy and energy dispersive x-ray analysis after hydrating 7, 28, and 90 days. All mixtures were prepared with a water/cement weight ratio of 0.4. Weight ratios of pCP/cement were as follows: 0, 0.04, 0.1 and 0.2. Samples were polished and examined for morphological differences and compositional variations. The smoothness of the polished surface was found to increase with hydration time as well as pCP concentration. X-ray dot maps and microprobe analyses indicate an even distribution of pCP within the hydrated cement paste. However, there is an increase in the mean and standard deviation of the Ca+Mg)/Cl atomic ratio with increasing hydration time for all pCP containing specimens. Although this ratio was higher for inclusions than for the matrix, the detection of Cl in the inclusions suggests a possible interaction between pCP and unhydrated clinker.

Solidification/stabilization of a synthetic electroplating sludge in cementitious binders containing NaOH

Abstract Solidification/stabilization of a highly concentrated synthetic electroplating waste sludge by cementitious mixtures containing NaOH was studied. The sludge contained 86.2 mg/g Ni, 84.1 mg/g Cr, 18.8 mg/g Cd, and 0. 137 mg/g Hg and before mixing was dewatered to 25% solids. It was stabi- lized by ordinary Type I portland cement (OPC), an OPC/Class F fly ash mixture (referred to as CFA), and a lime/Class C fly ash mixture (referred to as LFA). Mix ratios of OPC: sludge of 0.3: 1, OPC:fly ash:sludge of 0.2:0.5: 1, and lime:fly ash:sludge of 0.3:0.5:1 were used, respectively. NaOH was added to each mix at 0 (control sample), 2, 5 and 8% by weight of solidified binder. A set of binder samples without sludge, but con- taining 8% NaOH, was also prepared. The microstructure, microchemistry, and component phases present in the binders after curing were determined by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry. The chemical species present in the sludge were not significantly affected by the high pH produced by NaOH; the sample showing the least effect was CFA/sludge. Ettringite was formed in CFA /sludge samples containing up to 5% NaOH, and in CFA/sludge and LFA/sludge containing up to 2% NaOH. NaOH reacted with the binders to produce phases containing Na plus minor amounts of Cr and Ni.

A study of the effects of nickel chloride and calcium chloride on hydration of Portland cement

Portland cement samples containing amounts of CaCl2 and NiCl2 ranging from approximately 1% to 20% by weight have been examined by 29Si and 27Al solid-state MAS NMR as a function of time, and some of the mature pastes have been characterized by X-ray diffraction. Changes in physical properties that had been previously observed as a function of amounts of salt added are clearly traceable to differences in the silicate matrices. Low concentrations of both salts promote Q1 formation, but high concentrations result in formation of much more Q2 at the expense of Q1. Both salts accelerate both aluminate and silicate hydration, and the effects appear to be almost entirely due to chloride. Minor variations in hydration rates at high Ni concentrations may be the result of nickel salt precipitation.