Personal Research Database

Full Text: W\Was Man18, 219.pdf

Abstract: The ability of sugar industry mud to adsorb Basic Red-22 dye has been studied in two modes of operation. That is, in batch systems and continuous flow systems. Langmuir and Freundlich constants have been determined. In continuous flow system, the influence of varying parameters such as bed depth and solution flowrate has been studied. The bed depth service time (BDST) has been used to analyse the experimental data and identify design correlations. The feasibility of sugar-industry-mud in removal of Basic Red-22 dye from liquid waste streams was addressed.

Keywords: Fixed-Bed, Natural Adsorbents, Color Removal, Equilibrium, Hardwood, Peat, Diffusion, Systems, Adsorption, Fixed Bed, Color Removal, Dyes, Sugar-Industry-Mud, Industrial Wastewater

Lemieux, P.M., Ryan, J.V., French, N.B., Haas, Jr., W.J., Priebe, S. and Burns, D.B. (1998), Results of the September 1997 DOE/EPA demonstration of multimetal continuous emission monitoring technologies. Waste Management, 18 (6-8), 385-391.

Full Text: W\Was Man18, 385.pdf

Abstract: In September 1997, the U.S. Department of Energy (DOE) and U.S. Environmental Protection Agency (EPA) co-sponsored a demonstration of several multimetal continuous emission monitors (CEMs). The demonstration, performed at the EPA National Risk Management Research Laboratory, Air Pollution Prevention and Control Division’s combustion laboratory in Research Triangle Park, NC, involved the side-by-side testing of seven multimetal CEMs at various stages of commercialization. A series of tests were performed to compare results from the multimetal CEMs to Method 0060, the EPA reference method (RM) for metals emission measurements, using the relative accuracy test audit (RATA) protocol. The EPA operated the test facility and performed the RM sampling, and each multimetal CEM was operated by the instrument’s respective developer. To accomplish these tests, an aqueous solution of six toxic metals (arsenic, beryllium, cadmium, chromium, lead, and mercury), along with flyash from a coal-fired utility boiler, was injected into the afterburner of the EPAs rotary kiln incinerator simulator facility to generate a combustor flue gas with realistic post-flue gas cleaning system particulate loadings and target metals concentrations of approximately 15 and 75 µg/m³, which constituted the low and high concentration test conditions. The multimetal CEMs that participated in the test included two laser-induced breakdown spectroscopy (LIBS) systems, two inductively coupled plasma (ICP) systems, a spark-induced breakdown spectroscopy (SIBS) system, a hazardous element sampling train with X-ray fluorescence (HEST/XRF), and a microwave plasma system. Ten RM-CEM sample pairs were taken at both the low and high concentration test conditions, and the relative accuracies of the multimetal CEMs were calculated. This test provided performance data that will be used to assess the current state of the art in multimetal CEMs. Published by Elsevier Science Ltd. All rights reserved.

Holbert, C. and Lighty, J.S. (1998), Trace metals behavior during the thermal treatment of paper-mill sludge. Waste Management, 18 (6-8), 423-431.

Full Text: W\Was Man18, 423.pdf

Abstract: The objective of the present study is to investigate trace metals (Cd, Cr, and Pb) behavior during thermal treatment of sludge wastes. Paper mill sludge enriched with Cd, Cr, and Pb was subjected to different thermal regimes using two different bench-scale reactors. Metals retention in the resultant ash is discussed as is the influence of structural modifying additives. Ash was characterized using leachability tests to determine the environmental availability of the trace metals and provide insight as to the extent of metals immobilization within the ash matrix. The bulk of the ash appears to be supermicron particles composed of individual fragments kept together by an irregular framework. Ash morphology appears unchanged throughout the temperature regime investigated with the exception of the 900°C ash which exhibited signs of localized melting. Cadmium and chromium partitioning behavior is similar for both reactors, with metal retention by the ash strongly influenced by treatment temperature. Lead behavior exhibits significant differences between the two reactors. Under oxidizing conditions, 95 to 100% of the lead is retained by the ash and occurs as an immobilized form resistant to leaching using a strong mineral acid (HNO₃). Structural modifying additives did not increase metals retention or decrease metals leachability from the ash matrix. Alternatively, these additives appear to have a detrimental effect upon metals immobilization by the ash. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Incineration, Waste, Sorbents, Cadmium, Removal, Lead

Ho, T.C., Yang, P., Kuo, T.H. and Hopper, J.R. (1998), Characteristics of mercury desorption from sorbents at elevated temperatures. Waste Management, 18 (6-8), 445-452.

Full Text: W\Was Man18, 445.pdf

Abstract: This study investigated the dynamic desorption characteristics of mercury during the thermal treatment of mercury-loaded sorbents at elevated temperatures under fixed-bed operations. Experiments were carried out in a 25.4 mm ID quartz bed enclosed in an electric furnace. Elemental mercury and mercuric chloride were tested with activated carbon and bauxite. The experimental results indicated that mercury desoption from sorbents was strongly affected by the desorption temperature and the mercury-sorbent pair. Elemental mercury was observed to desorb faster than mercuric chloride and activated carbon appeared to have higher desorption limits than bauxite at low temperatures. A kinetic model considering the mechanisms of surface equilibrium, pore diffusion and external mass transfer was proposed to simulate the observed desorption profiles. The model was found to describe reasonably well the experimental results. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Mercury, Desorption, Mercury Loaded Sorbents, Thermal Treatment

Hawk, G.G. and Aulbaugh, R.A. (1998), High vacuum indirectly-heated rotary kiln for the removal and recovery of mercury from air pollution control scrubber waste. Waste Management, 18 (6-8), 461-466.

Full Text: W\Was Man18, 461.pdf

Abstract: In the mining industry, mercury is often associated with various ores, particularly copper and lead. To meet Environmental Protection Agency (EPA) and State air emission regulations, smelters must remove mercury vapors from hot exhaust gases, usually through the use of scrubbing solutions. Most of the mercury is precipitated out of the waste scrubbing solutions as the sulfide and the sludge dewatered in a filter press. SepraDyne Corporation (Denton, TX, USA) has conducted pilot-scale treatability studies of dewatered acid plant blowdown sludge generated by a copper smelter using its recently patented high temperature and high vacuum indirectly-heated rotary retort technology. This unique rotary kiln is capable of operating at internal temperatures up to 850°C with an internal pressure of 50 torr and eliminates the use of sweep gas to transport volatile substances out of the retort. By removing non-condensables such as oxygen and nitrogen at relatively low temperatures and coupling the process with a temperature ramp-up program and low temperature condensation, virtually all of the retort off-gases produced during processing can be condensed for recovery. The combination of rotation, heat and vacuum produce the ideal environment for the rapid volatilization of virtually all organic compounds, water and low-to-moderate boiling point metals such as arsenic, cadmium and mercury. Atmospheric oxygen can readily be reduced to very low concentrations within the kiln so that combustion does not take place. Initial concentrations of mercury in the waste ranged from 565 to 1260 mg/kg. The waste was processed in a 1.5 cubic foot capacity batch pilot unit at temperatures ranging from 427 to 649°C at a pressure of 76 torr. Total processing time ranged from 1.5 to 4.0 h. The processed material contained total mercury concentrations ranging from 0.065 mg/kg when processed at 649°C to an average of 2.2 mg/kg when processed at 427°C, The vaporized mercury was recovered as elemental mercury in a low temperature condenser. Mercury emissions averaged approximately 6.5 µg/M^-3, significantly below the Maximum Achievable Control Technology (MACT) standard of 40 µg/M-3, Based upon the success of these tests, a contract was let and a commercial scale unit was built. The 2-ton per batch commercial unit was installed at the copper smelter and began operations in late June 1998. As of the end of October, approximately 500 tons of mercury-contaminated acid blowdown sludge had been processed to below the specified treatment criteria of 10 mg/kg total mercury. (C) 1999 Elsevier Science Ltd. All rights reserved.

Palfy, P., Vircikova, E. and Molnar, L. (1999), Processing of arsenic waste by precipitation and solidification. Waste Management, 19 (1), 55-59.

Full Text: W\Was Man19, 55.pdf

Abstract: As a consequence of more stringent environmental legislation being applied in Slovakia, traditional ways of arsenic waste treatment no longer became acceptable. For that reason it has been necessary to develop a cheap and effective method for processing of arsenic sludge which is accumulating in the reaction tower during the carbon dioxide refining in the VETROCOKE technology. A substantial part of the problem is to reach a compromise between reasonable operation costs of technology and sufficient long-term stability of the disposable product. The proposed method of arsenic stabilisation together with the other toxic elements present is based on progressive reduction of their solubility by a series of precipitation and solidification agents. The key factor of successful arsenic fixation is embedding of calcium and ferric arsenates/arsenites in the cement matrix. It is possible to reduce original arsenic solubility of 6430 mg/l from untreated waste to 0.823 mg/l from final solidificate by this technique. Leaching tests were conducted in distilled water at 25°C, without pH value control, solid to liquid ratio was 1: 10, mixing speed was 150 rpm. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Arsenic, Precipitation, Solidification, Leach Tests, Removal

Özer, A., Özer, D., Dursun, G. and Bulak, S. (1999), Cadmium(II) adsorption on Cladophora crispata in batch stirred reactors in series. Waste Management, 19 (3), 233-240.

Full Text: W\Was Man19, 233.pdf

Abstract: In this study, the adsorption of Cadmium(II) ions onto Cladophora crispata was investigated in a two-staged batch reactor. The sorption phenomenon was expressed by the Freundlich and Langmuir adsorption isotherms and these expressions were used for the calculation of the equilibrium value of the residual Cadmium(II) concentration at each stage. The experimental equilibrium values were compared with the values obtained from Freundlich and Langmuir isotherm equations. These results showed that the increase in biomass quantity or the increase of X_o/V_o ratios affected the quantities of cadmium removed from aqueous solution.

Keywords: Rhizopus-arrhizus, Biosorption, Uranium, Removal, Mechanism, Lead(II), Thorium, Adsorption, Isotherm, Waste Water, Multi-Staged Reactor

Kiyak, B., Özer, A., Altundoğan, H.S., Erdem, M. and Tümen, F. (1999), Cr(VI) reduction in aqueous solutions by using copper smelter slag. Waste Management, 19 (5), 333-338.

Full Text: W\Was Man19, 333.pdf

Abstract: The ability of Copper Smelter Slag (CSS) to reduce Cr(VI) in aqueous solutions has been investigated. The extent of reduction is dependent on the amounts of acid and reductant, contact time, Cr(VI) concentration, temperature of the solution and particle size of CSS. The amount of acid is the most important variable affecting the reduction process. When twice the amount of acid required with respect to Cr(VI) was used, Cr(VI) in 100 mi solution (100 mg/l) was completely reduced in a contact period less than 5 min by a 10 g/l dosage of CSS. Reduction efficiency increased with increase in temperature of solution, showing that the process is endothermic. Reduced chromium, and iron and other metals dissolved from CSS were effectively precipitated by using NaOH or calcinated carbonatation sludge from sugar plant. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Copper Smelter Slag, Carbonatation Sludge, Cr(VI) Reduction, Chromium Removal

Turner, D.R. and Pabalan, R.T. (1999), Abstraction of mechanistic sorption model results for performance assessment calculations at Yucca Mountain, Nevada. Waste Management, 19 (6), 375-388.

Full Text: W\Was Man19, 375.pdf

Abstract: Sorption onto minerals in the geologic setting may help to mitigate potential radionuclide transport from the proposed high-level radioactive waste repository at Yucca Mountain (YM), Nevada. An approach is developed for including aspects of more mechanistic sorption models into current probabilistic performance assessment (PA) calculations. Data on water chemistry from the vicinity of YM are screened and used to calculate the ranges in parameters that could exert control on radionuclide sorption behavior. Using a diffuse-layer surface complexation model, sorption parameters for Np(V) and U(VI) are calculated based on the chemistry of each water sample. Model results suggest that lognormal probability distribution functions (PDFs) of sorption parameters are appropriate for most of the samples, but the calculated range is almost five orders of magnitude for Np(V) sorption and nine orders of magnitude for U(VI) sorption. Calculated sorption parameters may also vary at a single sample location by almost a factor of 10 over time periods of the order of days to years due to changes in chemistry, although sampling and analytical methodologies may introduce artifacts that add uncertainty to the evaluation of these fluctuations. Finally, correlation coefficients between the calculated Np(V) and U(VI) sorption parameters can be included as input into PA sampling routines, so that the value selected for one radionuclide sorption parameter is conditioned by its statistical relationship to the others. The approaches outlined here can be adapted readily to current PA efforts, using site-specific information to provide geochemical constraints on PDFs for radionuclide transport parameters. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: High-Level Radioactive Waste Repository, Water Chemistry, Sorption, Radionuclide Transport, Surface Complexation, Adsorption, Components, Transport

Li, X.Z., Zhao, Q.L. and Hao, X.D. (1999), Ammonium removal from landfill leachate by chemical precipitation. Waste Management, 19 (6), 409-415.

Full Text: W\Was Man19, 409.pdf

Abstract: The landfill leachate in Hong Kong usually contains quite high NH₄⁺-N concentration, which is well known to inhibit nitrification in biological treatment processes. A common pre-treatment for reducing high strength of ammonium (NH₄⁺-N) is by an air-stripping process. However, there are some operational problems such as carbonate scaling in the process of stripping. For this reason, some technical alternatives for NH₄⁺-N removal from leachate need to be studied. In this study, a bench-scale experiment was initiated to investigate the feasibility of selectively precipitating NH₄⁺-N in the leachate collected from a local landfill in Hong Kong as magnesium ammonium phosphate (MAP). In the experiment, three combinations of chemicals, MgCl₂. 6H₂O+Na₂HPO₄. 12H₂O, MgO + 85% H₃PO₄, and Ca(H2PO₄)₂. H₂O + MgSO₄. 7H₂O, were used with the different stoichiometric ratios to generate the MAP precipitate effectively. The results indicated that NH4+-N contained in the leachate could be quickly reduced from 5618 to 112 mg/l within 15 min, when MgCl₂. 6H₂O and Na₂HPO₄. 12H₂O were applied with a Mg²⁺: NH₄⁺: PO₄^3- mol ratio of 1: 1: 1. The pH range of the minimum MAP solubility was discovered to be between 8.5 and 9.0. Attention should be given to the high salinity formed in the treated leachate by using MgCl₂. 6H₂O and Na₂HPO₄. 12H₂O, which may affect microbial activity in the following biological treatment processes. The other two combinations of chemicals [MgO+85% H₃PO₄ and Ca(H₂PO4)₂. H₂O + MgSO₄. 7H₂O] could minimise salinity after precipitation, but they were less efficient for NH₄⁺-N removal, compared with MgCl₂. 6H₂O and Na₂HPO₄. 12H₂O. COD had no significant reduction during this precipitation. It was found that the sludge of MAP generated was easily settled within 10 min to reach its solids content up to 27%. The other characteristics including capillary suction time (CST) and dry density (DD) of the MAP sludge were also tested. The experimental results indicate that the settled sludge is quite solid and can be directly dumped at a landfill site even without any further dewatering treatment. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Ammonium (NH₄⁺-N), Landfill Leachate, Precipitation, Magnesium-Ammonium-Phosphate (MAP), Phosphate, Nitrogen

Satyanarayana, J., Murthy, G.S. and Sasidhar, P. (1999), Adsorption studies of caesium on zirconium molybdoarsenate (ZrMAs). Waste Management, 19 (6), 427-432.

Full Text: W\Was Man19, 427.pdf

Abstract: The applicability of zirconium molybdoarsenate (ZrMAs) for efficient removal of Cs from aqueous solution by adsorption has been investigated. The kinetics of adsorption of caesium ions has been studied by using radioanalytical procedure over a concentration range (10^-4)-10^-2 mol dm^-3) and in the temperature range (303-318 K). The results showed that the uptake follows the first order rate law with respect to caesium concentration and obeys Langmuir and Modified Freundlich adsorption isotherms in the concentration studied. The effect of temperature on adsorption equilibrium has been studied and the thermodynamic quantities (H°, G° and S°) has been evaluated. They showed that the process is exothermic in nature. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Zirconium Molybdoarsenate, Caesium, Langmuir Isotherm, Modified Freundlich Isotherm, Adsorption

Barakat, M.A. (1999), Recovery of metal values from zinc solder dress. Waste Management, 19 (7-8), 503-507.

Full Text: W\Was Man19, 503.pdf

Abstract: Zinc solder dress containing 14.8% Sn, 16.3% Pb 0.41% Al and 64.5% Zn was leached with 3% H₂SO₄ at 45°C for 1 h. Zinc and aluminum went into solution, whereas lead and tin remained with the residue. Aluminum was selectively precipitated as calcium aluminum carbonate by treating the sulphate leachate with limestone at pH 4.8. Zinc sulphate solution was either evaporated to obtain zinc sulphate crystals or precipitated as basic zinc carbonate at pH 6.8. The undissolved lead and tin were leached with 5 M hot hydrochloric acid. The major part of lead chloride (congruent to 73%) was separated by cooling the leached products down to room temperature. From the soluble fraction, tin was recovered as hydrated tin oxide by alkylation with caustic soda at pH 2.4, while the remaining lead was separated at pH 8.5 as lead hydroxide. A process flowsheet had been suggested which involved two-stage hydrometallurgical treatment. Parameters affecting the recovery efficiency of the suggested method such as temperature, time, pH and acid: solid stoichiometric ratio were investigated. Results obtained revealed that the optimum leaching conditions were achieved by using 20 mi of 3% H₂SO₄ acid/g dress for 1 h at 45°C. Recovery efficiency of the metal salts was 99.1, 99.4, 99.6 and 99.5% for Zn, Al, Pb and Sn respectively. Recovery efficiency was related to the solubility of the concerned salts under the given experimental conditions. (C) 1999 Elsevier Science Ltd. All rights reserved.

Keywords: Solder Dress, Acid Leaching, Zinc, Aluminum, Lead, Tin, Recovery, Separation, Lead

Ficarella, A. and Laforgia, D. (2000), Numerical simulation of flow-field and dioxins chemistry for incineration plants and experimental investigation. Waste Management, 20 (1), 27-49.

Full Text: W\Was Man20, 27.pdf

Abstract: The development of incineration units (kiln and afterburner) for hazardous wastes in terms of design and fluid-dynamic optimization has been carried out together with definition of a new design methodology. An extensive theoretical and experimental analysis has been carried out on a hazardous waste incineration pilot plant to test the methodologies and to optimize the entire system in terms of reduction of the polluting emissions and higher combustion efficiency. In particular, the combustion chamber and the afterburner have been thoroughly studied. A computer code for multiple chemical reactions occurring in an afterburner chamber of an incineration system was developed, based on the equations presented herein, to evaluate the decomposition rate of dioxins for different chamber geometries. The results of these analysis are presented herein. (C) 2000 Elsevier Science Ltd. All rights reserved.

Crannell, B.S., Eighmy, T.T., Krzanowski, J.E., Eusden, J.D., Shaw, E.L. and Francis, C.A. (2000), Heavy metal stabilization in municipal solid waste combustion bottom ash using soluble phosphate. Waste Management, 20 (2-3), 135-148.

Full Text: W\Was Man20, 135.pdf

Abstract: Heavy metal chemical stabilization with soluble PO₄^3- was assessed for bottom ash from combustion of municipal solid waste. Bottom ash can contain heavy metals (e.g. Pb) that can leach. An experimental dose of 0.38 mols of soluble PO₄^3- per kg of residue was used without optimizing the formulation for any one heavy metal. The reduction in the fraction available for leaching according to the total availability leaching test was 52% for Ca, 14% for Cd, 98% for Cu, 99% for Pb, and 36% for Zn. pH-dependent leaching (pH 4, 6, 8) showed that the treatment was able to reduce equilibrium concentrations by 0.5 to 3 log units for these heavy metals. Bulk and surface spectroscopies showed that both crystalline and amorphous precipitates were present as insoluble metal phosphate reaction products. Dominant reaction products were calcium phosphates, tertiary metal phosphates, and apatite family minerals. Observed phases included, beta-Ca₃(PO₄)₂ (tertiary calcium phosphate); Ca₅(PO₄)₃OH (calcium hydroxyapatite); Pb₅(PO₄)₃Cl (lead chloropyromorphite); and Pb₅(PO₄)₃OH (lead hydroxypyromorphite). These are considered to be very geochemically stable mineral phases. The geochemical thermodynamic equilibrium model MINTEQA2 was modified to include both extensive phosphate minerals and simple ideal solid solutions in order to better model pH-dependent leaching. Both end members [e.g, Pb₅(PO₄)₃Cl, beta-Ca₃(PO₄)₂] and ideal solid solutions [e.g. (Pb₂, Ca)(PO₄)₂] were observed as controlling solids for Ca²⁺, Zn²⁺, Pb²⁺, and Cu²⁺. Controlling solids were not identified for Cd²⁺ because pH dependent concentrations were generally below detection limits. The divalent metal cations in bottom ash were effectively stabilized by treatment with soluble PO₄^3-. (C) 2000 Elsevier Science Ltd. All rights reserved.

Keywords: Municipal Solid Waste Combustion Bottom Ash, Lead, Heavy Metals, Phosphate, Stabilization, Lattice-Constant Measurements, Lead Immobilization, Hydroxyapatite, Surface, Sorption, Copper, Soils, Apatite, Cadmium, Cd²⁺

Haugsten, K.E. and Gustavson, B. (2000), Environmental properties of vitrified fly ash from hazardous and municipal waste incineration. Waste Management,