This study focuses on the Kaohsiung industrial pier sediment survey, assessment and feasibility study of the approach. In this study, field monitoring operations, including the close Salt Water River mouth area of the industrial port (area A), the far Salt Water River mouth area of the industrial port (area B) and for the factories and shipyards at the junction of the terminal area (area C), The sampling of sediments of three core and three surface sediments of area A that used as treating test at laboratory. The survey results show that the industrial pier some heavy metals in the sediment concentration is higher than the quality indicators in the sediment above the limit (ULV), especially copper and zinc. In addition, the concentration of heavy metals of industrial pier area A, B and C of the sediment at least one of them is than current soil control standard. Among them, the frequency of exceeding control standards of copper concentration is the highest, the surface sediments of area A, B and C were about 75%, 42% and 0% respectively, while the core sediments were about 20%, 90% and 15%. These results indicate that the industrial pier sediment required to carry out appropriate pre-treatment to reclamation land to recycling. After investigation, simulation and estimation, the required appropriate treatment sediment in order to landfill volume of industrial pier area A and B (Salt Water River mouth) were approximately 40,000 and 36,400 cubic meters, the total approximately 76,400 cubic meters. Industrial pier is located in the Salt Water River mouth, and therefore withstand the effects of pollutants of the upstream sources flowed in, and than the sediment quality was poor. Sediments were accumulated in the bottom should be removed and sediments at the upstream Salt Water River should be treated too, the remediation and pollution source control for the future to improve the sediment quality is the most important work in Taiwan. In this study, chemical washing and chemical oxidation of the two treatment technology for industrial pier sediment organic pollutants (total petroleum hydrocarbons (TPH) as the target pollutants) to deal with the feasibility test. Sediment to be processed was collected neart the industrial pier, the pH value of approximately 7.1, the moisture content was 43.9%, 20.1% organic matter content, while the particle size composition of mainly fine particles (silt + clay) to about 84.3% handling may be more difficult. The sediments of the TPH concentration of 8,691 mg / kg. Three surfactants Simple Green (SG), Triton X-100 (TX-100) and Tween 80 (TW80) were used at sediment washing test,washing with 60 pv and 5% (v / v) SG could remove 97.3% TPH at the end of the mud; 0.5% (v / v) TX-100 could remove 96.8% TPH; washing with 30 pv, 1% (v / v) TX-100 could remove 94.6% the TPH; washing with 10 pv, 5% (v / v) TX-100 could remove 96.7% TPH; but TW80 leaching ineffective. Oxidation processing, applied 6% H2O2 reaction 180 min, 58.2% of TPH could be removed. Connection of washing and oxidation treatment process, could be removed total of 86% of TPH. The sediment surface morphology before and after treatment were observed by SEM were not significantly different, no surfactant emulsion was left at sediment after treated, this result revealed the connection of washing and oxidation treatment process could remove most of TPH and less harmful to the environment was an available technique.

The presence of coal tars in the subsurface associated with former manufactured gas plants (MGPs) offers a remediation challenge due to their complex chemical composition, dissolution behaviour and recalcitrant characteristics. A former MGP site in Clearwater Beach, Florida was characterized and bench-scale analyses were conducted to assess the potential for in situ chemical oxidation (ISCO) using persulfate to treat MGP residuals. Completion of a conceptual site model identified a homogeneous, silty sand aquifer, with an average hydraulic conductivity of approximately 2.3x10-3 cm/s and a groundwater flow rate of 2 cm/day in the direction of S20°E. Six source zones, three near the water table and three in the deep aquifer were estimated to have a total volume of 108 m3. A multi-level well transect was installed to monitor concentrations of dissolved compounds and to estimate mass discharge downgradient of the source zones over time. On average, the morphology of the aqueous concentrations remained consistent with time. A total mass discharge across the transect of 94 mg/day was estimated for site-specific compounds. Bench-scale tests were conducted on aquifer sediments and groundwater samples. The aquifer was determined to have a low buffering capacity, low chemical oxygen demand, and low natural oxidant interaction (NOI) with persulfate. Aqueous batch experiments identified the potential for iron (II) activated persulfate to reduce concentrations of BTEX and PAHs below method detection limits (MDLs). Unactivated persulfate was able to reduce BTEX concentrations to below MDLs after 14 days; however, the concentration of PAH compounds remained above MDLs after 14 days. Higher iron doses within the system were shown to be more effective in reducing BTEX and PAH compounds. Column experiments designed to mimic site conditions were used to evaluate the feasibility of persulfate treatment on impacted sediments from the Clearwater site. Two sets of column experiments were conducted: one using unactivated persulfate followed by alkaline activated persulfate; and one using iron (II) activated persulfate. On average, unactivated persulfate was able to reduce BTEX and PAH aqueous effluent concentrations by > 75% and 40%, respectively, after a total dose of 60 g/g soil. Two additional doses of alkaline activated persulfate (total persulfate dose of ~80g/g soil) in these columns were able to further reduce effluent BTEX and PAH concentrations by > 90% and > 75%, respectively. Iron (II) activated persulfate reduced effluent BTEX concentrations by > 70% and PAHs by > 65% after a total dose of 35 g/g soil. Average reductions in mass for BTEX and PAH compounds were approximately of 48% and 26% respectively in the iron (II) activated persulfate columns, and 24% and 10%, respectively in the alkaline activated persulfate columns. The potential for the ability to use in situ chemical oxidation using persulfate for the remediation of MGP residuals in the subsurface is evaluated using field measurements and bench-scale experimentation. The reductions observed in aqueous phase compounds in MGP groundwater as observed in the laboratory indicate the potential for reductions in groundwater concentrations at this and other contaminated former MGP sites. However, column experiments, indicating the inability for activated persulfate to reduce all identified compounds in the MGP NAPL suggest source treatment with activated persulfate would not reduce concentrations to below Florida Department of Environmental Protection natural attenuation concentrations.

In situ chemical oxidation using permanganate is an approach to organic contaminant site remediation. Manganese dioxide particles are products of permanganate reactions. These particles have the potential to deposit in the subsurface and impact the flow-regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport and contact between the oxidant and contaminants of concern. The goals of this research were to determine if MnO2 can be stabilized/controlled in an aqueous phase, and to determine the dependence of particle stabilization on groundwater characteristics. Bench-scale experiments were conducted to study the ability of four stabilization aids (sodium hexametaphosphate (HMP), Dowfax 8390, xanthan gum, and gum arabic) in maintaining particles suspended in solution under varied reaction conditions and time. Variations included particle and stabilization aid concentrations, ionic content, and pH. HMP demonstrated the most promising results, as compared to xanthan gum, gum arabic, and Dowfax 8390 based on results of spectrophotometric studies of particle behavior, particle filtration, and optical measurements of particle size and zeta potential. HMP inhibited particle settling, provided for greater particle stability, and resulted in particles of a smaller average size over the range of experimental conditions evaluated compared to results for systems that did not include HMP. Additionally, HMP did not react unfavorably with permanganate. These results indicate that the inclusion of HMP in a permanganate oxidation system improves conditions that may facilitate particle transport.

No description available.

Landfill fires are relatively common incidents that landfill operators encounter which have great impact on landfill structure and the environment. According to a U.S. Fire Administration report in 2001, an average of 8,300 landfill fires occurs each year in the United States, most of them in the spring and summer months. Subsurface spontaneous fires are considered the most dangerous and difficult to detect and extinguish among landfill fires. Few studies have been conducted on spontaneous fires in landfills. Information regarding the thermal behavior of solid waste is not available nor have measurements been made to evaluate spontaneous ignition of solid waste. The purpose of this research was to provide information concerning the initiation of spontaneous ignition incidents in landfills, and investigate the conditions favoring their occurrence. This study enabled better understanding of the self-heating process and spontaneous combustion in landfills. Effects of parameters critical to landfill operation on spontaneous combustion were determined. Spontaneous combustion occurs when materials are heated beyond the ignition temperature. Temperature rise occurs inside the landfill due to exothermic reactions which cause self-heating of the solid waste. Oxygen introduction leading to biological waste degradation and chemical oxidation is believed to be the main cause of rising solid waste temperatures to the point of ignition. A survey was distributed to landfill operators collecting information regarding spontaneous firs incidents in their landfills. Survey results raised new questions necessitating further study of subsurface fires incidents. Subsurface spontaneous fires were not restricted to any landfill geometry or type of waste (municipal, industrial, commercial, and construction and demolition). Results showed that landfill fires occur in landfills that do and do not recirculate leachate. Although new methods have been developed to detect subsurface fires, landfill operators depend primarily on visual observation of smoke or steam to detect the subsurface fires. Also, survey results indicated that excavating and covering with soil are the most widespread methods for extinguishing subsurface fires. Methane often has been suspected for initiating spontaneous subsurface firs in the landfill. However, combustible mixture of methane and oxygen requires very high temperature to ignite. In this study it was shown that spontaneous fires are initiated by solid materials with lower ignition points. Laboratory tests were conducted evaluating the effect of moisture content, oxygen concentration and leachate on spontaneous ignition of solid waste. A new procedure for testing spontaneous ignition is described based on the crossing-point method. The procedure was used to study the spontaneous combustion of solid waste and determine the auto-ignition temperature of the solid waste components and a synthesized solid waste. Correlations have been established between auto-ignition temperature, specific weight and energy content and between self-heating temperature and specific weight. Correlations indicated that compaction can help avoid spontaneous combustion in the landfill. Dense materials require higher energy to increase in temperature and limit the accessibility of oxygen. In the experimental work, moisture was found to promote both biological and chemical self-heating. Increasing moisture content lowers the solid waste permeability and absorbs more energy as it evaporates. Dissolved solids in leachate were found to promote self-heating and ignition more than distilled water. Varying oxygen concentrations indicated that heat generation occurs due to chemical oxidation even at oxygen concentration as low as 10% by volume. However, at 10% by volume oxygen, solid waste did not exhibit thermal runaway nor flammable combustion. At 0% by volume oxygen, tests results indicated occurrence of self-heating due to slow pyrolysis. A numerical one-dimensional energy model was created to simulate temperature rise in landfill for four different scenarios. Using the results from the laboratory experiment, the model estimated the heat generation in solid waste due to chemical reactions. Results from the scenario simulations indicated that moisture evaporation is the major heat sink in the landfill. The model showed that gas flow has a cooling effect due to increasing amount of evaporated water and can control the temperature inside the landfill. The model showed that a temperature higher than the biological limit can be maintained in the landfill without initiating spontaneous fire.

This study evaluated the effect of chemical oxidation on the bioremediation of polycyclic aromatic hydrocarbons (PAHs) contaminated sediments. Sediments were treated in sequential steps: biotreatment, chemical oxidation, and biotreatment. The first biotreatment step was initiated via addition of nutrients, microbial seeds, co-metabolites, and/or Tween 80 (surfactant). The chemical oxidation step was conducted using Fenton?s Reagent, ozonation, and peroxone (combination of ozone and hydrogen peroxide). The objective was to enhance the PAHs bioavailability via oxidation of natural organic matter and transformation of Heavy PAHs into more biodegradable compounds. Biotreatment was reestablished as a final polishing step to further degrade remaining PAHs and more biodegradable oxidation by-products. The proposed mechanism was proven successful for the less contaminated sediment (Scioto River) and not the highly contaminated and chemically more complex sediment (Lake Superior). Given this mechanism only worked for the Scioto River sediment, further research is required to determine the mechanisms limiting treatment.

No description available.

Fractured rock formations represent a valuable source of groundwater and can be highly susceptible to contamination by dense, non-aqueous phase liquids (DNAPLs). The goal of this research is to evaluate the effectiveness of three accepted remediation technologies for addressing DNAPL contamination in fractured rock environments. The technologies under investigation in this study are chemical oxidation, bioremediation, and surfactant flushing. Numerical simulations were employed to examine the performance of each of these technologies at the field scale. The numerical model DNAPL3D-RX, a finite difference multiphase flow-dissolution-aqueous transport code that incorporates RT3D for multiple species reactions, was modified to simulate fractured rock environments. A gridding routine was developed to allow the model to accurately capture DNAPL migration in fractures and aqueous phase diffusion gradients in the matrix while retaining overall model efficiency. Reaction kinetics code subroutines were developed for each technology so as to ensure the key processes were accounted for in the simulations. The three remedial approaches were systematically evaluated via simulations in two-dimensional domains characterized by heterogeneous orthogonal fracture networks parameterized to be representative of sandstone, granite, and shale. Each simulation included a DNAPL release at the water table, redistribution to pools and residual, followed by 20 years of ‘ageing’ under ambient gradient conditions. Suites of simulations for each technology examined a variety of operational issues including the influence of DNAPL type and remedial fluid injection protocol. Performance metrics included changes in mass flux exiting, mass destruction in the matrix versus the fractures, and percentage of injected remedial fluid interacting with the target contaminant. The effectiveness of the three remediation technologies covered a wide range; the mass of contaminants destroyed were found to range from 15% to 99.5% of the initial mass present. Effectiveness of each technology was found to depend on a variety of critical factors particular to each approach. For example, in-situ chemical oxidation was found to be limited by the organic material present in the matrix of the rocks, while the efficiency of enhanced bioremediation was found to be related to factors such as the location of indigenous bacteria present in the domain and rate of bioremediation. In the chemical oxidation study, the efficiency of oxidant consumption was observed to be poor across the suite of scenarios, with greater than 90% of the injected permanganate consumed by natural oxidant demand. This study further revealed that the same factors that contributed to forward diffusion of contaminants prior to treatment are critical to this remediation method as they can determine the extent of contaminant destruction during the injection period. Bioremediation in fractured rock was demonstrated to produce relatively good results under robust first-order decay rates and active microorganisms throughout the fractures and matrix. It was demonstrated that under ideal conditions, of the total initial mass present, up to 3/4 could be reduced to ethene, indicating bioremediation may be a promising treatment approach due to the effective penetration of electron donor into the matrix during the treatment period and the ongoing treatment that occurs after injection ceases. However, when indigenous bacteria was assumed to exist only within the fractured walls of sandstone, it was found that under the same conditions, the rate of dechlorination was 200 times less than the Base Case. Since the majority of the mass resided in the matrix, lack of bioremediation in the matrix significantly reduced the effectiveness of treatment. Surfactant treatment with Tween-80 was proven to be a relatively effective technique in enhanced solubilisation of DNAPL from the fractures within the domain. However, by comparing the aqueous and sorbed mass at the start and end of the Treatment stage, it is revealed that surfactant treatment is not efficient in removing these masses that reside within the matrix. Furthermore, DNAPLs identified in dead end vertical fractures were found to remain in the domain by the end of the simulations across all scenarios studied; indicating that the injected surfactant experiences difficulty in accessing DNAPLs entrapped in dead end fractures. Altogether, the results underscore the challenge of restoring fractured rock aquifers due to the field scale limitations on sufficient contact between remedial fluids and in situ contaminants in all but the most ideal circumstances.

[pt] Efluentes contendo cianeto estão presentes em indústrias de importância como a minero-metalúrgica, siderúrgica, entre outras, constituindo estes potenciais riscos para os ecossistemas, devido à elevada toxicidade do cianeto. O alvo do presente trabalho foi estudar a cinética de degradação do cianeto com ácido de Caro (H2SO5), um poderoso oxidante produto da reação entre o H2SO4 e H2O2, e desenvolver um modelo matemático que envolvesse a oxidação de CN - e a decomposição simultânea do H2SO5. Os ensaios foram realizados em regime de batelada, e as amostras utilizadas na degradação foram soluções sintéticas de CN - livre. A metodologia experimental envolveu um desenho fatorial 24, levando em conta 4 variáveis: [CN-] mg/L, razão molar [H2SO5]:[CN-], pH e tipo de ácido de Caro, com a finalidade de avaliar o efeito de cada variável na cinética da degradação. A análise estatística mostrou que as variáveis mais preponderantes na cinética de degradação foram [CN-] mg/L e [H2SO5]:[CN-]. Uma avaliação físicoquímica mostrou também uma maior velocidade de degradação a um pH 9 em relação a um pH 11, enquanto que um tipo de [H2SO5] de razão molar H2SO4//H2O2 igual a 3:1 teve uma maior eficiência que utilizando um [H2SO5] de razão estequiométrica 1:1. O ácido de Caro mostrou-se efetivo na degradação de cianeto, permitindo que em condições de: [CN-]o = 400 mg/L, , pH = 9, razão molar [H2SO5]/[CN-] = 3:1, e tipo de [H2SO5] = 3:1, atingi-se uma concentração final de [CN-] < 0,2 mg/L em um t = 10 min. / [en] Effluents containing cyanides are generated in important industrial áreas such as mining-metallurgical, steelmaking, petrochemical, amongst others, carrying potential risks to the environment due to the high toxicity of cyanide. The aim of the present work is to study the kinetics of cyanide degradation with Caro s Acid (H2SO5), a powerful oxidant generated by the reaction between concentrated grades of H2SO4 and H2O2, and to develop a mathematical model involving CN - oxidation and simultaneous self-decomposition of H2SO5. The experiments were conducted in batches using synthetic solutions of free cyanide. The experimental methodology employed involved a 24 factorial design with the four factors: initial [CN-] mg/L, molar rate [H2SO5]:[CN-], pH e type of Caro s acid, with the aim to evaluate the effect of these factors in the process reaction kinetics. The statistical analyses showed that the most affecting variables were initial [CN-] mg/L and [H2SO5]:[CN-] molar ratio. Nevertheless a physicalchemical evaluation showed that also pH and type of Caro s Acid made of 1 or 3 moles of H2SO4 with 1 mole of H2O2, had effect on the kinetics. The highest observed reaction rate was obtained in the following conditions: initial [CN-] = 400 mg/L, molar ratio [H2SO5]/[CN-]= 3:1, pH = 9 and type of Caro s acid = 3 moles H2SO4 to 1 mole H2O2, achieving a value of [CN-] < 0,2 mg/L in t = 10 min.

Recentemente, o uso de persulfato em processo de oxidação química in situ em áreas contaminadas por compostos orgânicos ganhou notoriedade. Contudo, a matriz sólida do solo pode interagir com o persulfato, favorecendo a formação de radicais livres, evitando o acesso do oxidante até o contaminante devido a oxidação de compostos reduzidos presentes no solo ou ainda pela alteração das propriedades hidráulicas do solo. Essa pesquisa teve como objetivos avaliar se as interações entre a solução de persulfato com três solos brasileiros poderiam eventualmente interferir sua capacidade de oxidação bem como se a interação entre eles poderia alterar as propriedades hidráulicas do solo. Para isso, foram realizados ensaios de oxidação do Latossolo Vermelho (LV), Latossolo Vermelho Amarelo (LVA) e Neossolo Quartzarênico (NQ) com solução de persulfato (1g/L e 14g/L) por meio de ensaios de batelada, bem como a oxidação do LV por solução de persulfato (9g/L e 14g/L) em colunas indeformadas. Os resultados mostraram que o decaimento do persulfato seguiu modelo de primeira ordem e o consumo do oxidante não foi finito. A maior constante da taxa de reação (kobs) foi observada para o reator com LV. Essa maior interação foi decorrente da diferença na composição mineralógica e área específica. A caulinita, a gibbsita e os óxidos de ferro apresentaram maior interação com o persulfato. A redução do pH da solução dos reatores causou a lixiviação do alumínio e do ferro devido a dissolução dos minerais. O ferro mobilizado pode ter participado como catalisador da reação, favorecendo a formação de radicais livres, mas foi o principal responsável pelo consumo do oxidante. Parte do ferro oxidado pode ter sido precipitado como óxido cristalino favorecendo a obstrução dos poros. Devido à maior relação entre massa de persulfato e massa de solo, a constante kobs obtida no ensaio com coluna foi 23 vezes maior do que a obtida no ensaio de batelada, mesmo utilizando concentração 1,5 vezes menor no ensaio com coluna. Houve redução na condutividade hidráulica do solo e o fluxo da água mostrou-se heterogêneo após a oxidação devido a mudanças na estrutura dos minerais. Para a remediação de áreas com predomínio de solos tropicais, especialmente do LV, pode ocorrer a formação de radicais livres, mas pode haver um consumo acentuado e não finito do oxidante. Verifica-se que o pH da solução não deve ser inferior a 5 afim de evitar a mobilização de metais para a água subterrânea e eventual obstrução dos poros por meio da desagregação dos grãos de argila. / Recently the persulfate application for in situ chemical oxidation at areas contaminated by organic compounds gained notoriety. However, the persulfate can interact with the solid matrix of the soil favoring the formation of free radicals, avoiding the oxidant access to the contaminant due to the oxidation of reduced compounds present in the soil or by changing the hydraulic properties of the soil. This research aimed to evaluate if the interactions between the persulfate solutions and three Brazilian tropical soils could eventually interfere on the persulfate oxidation capacity and if the interaction between them could modify the hydraulic properties of the soil. For such, oxidation tests were performed with soils: Latossolo Vermelho (LV), Latossolo Vermelho Amarelo (LVA) and Neossolo Quartzarênico (NQ) with persulfate solution (1 and 14 g/L) through batch tests and LV oxidation by persulfate solution (9 and 14 g/L) on undisturbed columns. The results showed that persulfate decay followed a first order model and oxidant consumption was not finite. The higher reaction rate coefficient (kobs) was observed in the reactor with LV. This higher interaction was due to the difference in the mineralogical composition and surface area. Kaolinite, gibbisita and iron oxides showed greater interaction with persulfate. The pH reduction on the reactor solution caused the aluminum and iron leaching due to dissolution of minerals. The mobilized iron may have participated as a reaction catalyst favoring the formation of free radicals although it was the major responsible for the oxidant consumption. Part of oxidized iron may have been precipitated as crystalline oxide favoring the clogged pores. As a consequence of the higher mass proportion between persulfate and soil, the kobs constant obtained in the column test was 23 times higher than the one observed on the batch test, even utilizing a concentration 1.5 times lower than bath test. There was a reduction in the soil hydraulic conductivity and the water flow proved to be heterogeneous after oxidation due to changes in minerals structure. For remediation purposes in areas with predominance of tropical soils, especially LV, the formation of free radicals may occur but an accented and not finite oxidant consumption may happen. It is verified that the pH solution should not be inferior than 5 to prevent the mobilization of metals to the groundwater and a possible pores clogging by the breakdown of the clay grains.