Trichloroethene (TCE) and tetrachloroethene (PCE) are among the most commonly detected groundwater contaminants, and are often difficult to remediate due to their presence as dense non-aqueous phase liquids (DNAPLs) in the subsurface. The objective of this study was to assess the potential of using a passive in situ carbon/hydrogen releasing barrier system to bioremediate TCE-contaminated groundwater. The slow carbon/hydrogen releasing material would cause the aerobic cometabolism and reductive dechlorination of TCE in aquifer. The carbon/hydrogen releasing materials would release carbon when contacts with groundwater and release hydrogen after the anaerobic biodegradation of released carbon, thus cause the reductive dechlorination of TCE. Results from the microcosm study indicate that the addition of emulsified substrate, cane molasses, Simple GreenTM (a biodegradable surfactant), or lecithin would enhance the biodegradation rate of TCE under anaerobic conditions. However, addition of multivitamin would increase the bacterial population in the media but would not be able to enhance the TCE degradation rate. Results show that a significant pH drop was observed due to the production of organic acids after the aerobic biodegradation process of cane molasses and lecithin. This also caused the inhibition of microbial growth in microcosms. Results reveal that higher TCE removal efficiency was observed in microcosms with Simple GreenTM addition followed by the addition of cane molasses, lecithin, multivitamin, emulsified substrate, groundwater (without substrate addition). Results from the microcosm study indicate that the addition of emulsified substrate would enhance the biodegradation rate of TCE under anaerobic conditions. However, appearance of high nitrate concentration would inhibit the TCE degradation process due to the occurrence of denitrification. Compared with nitrate, high sulfate concentration would not have significant impact on the reductive dechlorination of TCE. Results reveal that higher TCE removal efficiency was observed in microcosms with emulsified substrate addition followed by the addition of high sulfate concentration, high nitriate concentration, groundwater (without substrate addition). Results from the gene analysis show that phenol monooxygenase, toluene monooxygenase, and toluene dioxygenase were observed in the microcosms with lecithin, cane molasses, Simple GreenTM, and emulsified substrate. This indicates that the addition of substrates would induce the potential of TCE-degrading enzyme. Addition of emulsified substrate and emulsified substrate in nitrate or sulfate-rich media would stimulate Dehalococcoides sp. to induce tceA, bvcA, and vcrA, enzymes for TCE reductive dechlorination.

Remediation of chlorinated ethene contaminated sites presents a problem for the environmental industry. Many innovative technologies exist to remove these chemicals from the subsurface; however, most of these technologies require extensive time and incur significant cost. A technology called bioremediation utilizes microorganisms to break down contaminants such as perchloroethene (PCE), trichloroethene (TCE), dichloroethene (DCE), and vinyl chloride (VC) to non-toxic compounds in a process called reductive dechlorination. Microorganisms that are capable of dechlorination usually require reducing conditions as well as bioavailable hydrogen and carbon sources. Emulsified vegetable oil has emerged as a cost-effective source of degradable organic matter to facilitate reductive dechlorination in the subsurface. Through Æ Ã -oxidation, microorganisms can break down the long chain fatty acids in vegetable oil into smaller fatty acids such as acetate, propionate, and butyrate. The fermentation of the oil provides reduced conditions as well as a slow release of hydrogen and carbon into the subsurface. This study consisted of an evaluation the effectiveness of emulsified vegetable oil in stimulating reductive dechlorination using sixteen laboratory microcosms constructed from soil and groundwater from an aquifer contaminated with TCE located at the Naval Weapons Station in Charleston, South Carolina. Each microcosm was monitored for chloroethenes, volatile fatty acids, long chain fatty acids, and total carbon on a weekly basis. Results show successful fermentation of fatty acids and reduced conditions favorable for dechlorination. / Master of Science

The objective of this research was to evaluate the treatment efficiency of a trichloroethylene(TCE)-contaminated aqueous solution and soil by combined technologies of the emulsified nanoscale zero-valent iron slurry (ENZVIS) and electrokinetic remediation process. Nanoiron was synthesized using the chemical reduction method by industrial grade chemicals. The synthesized nanoparticles contained elemental iron and iron oxide as determined by X-ray diffractmetry(XRD). Micrographs of FE-SEM have shown that a majority of nanoiron were in the size range of 30~50 nm. The stability study of food-grade soybean oil emulsion was conducted using six non-ionic surfactants and soybean oil. The results have shown that the emulsion prepared by mixed surfactants (Span 80 and Tween 40) and soybean oil yielded a better emulsion stability. Based on the above finding, the nanoiron slurry, soybean oil and aforementioned, mixed surfactants were used to prepare ENZVIS. Degradation of TCE by ENZVIS under various operating parameters was carried out in batch experiments. The experimental results have indicated that emulsified nanoiron outperformed nanoiron in TCE dechlorination rate. ENZVIS (0.75 g-Fe0/L) degradated TCE (initial conc.= 10 mg/L) down to 45 %. An increase of the oil dosage could improve the stability of the emulsion, but yielding a negative influence on degradation of TCE. Experimental results also showed that ENZVIS could remove TCE up to 94 % when pH=6. It was also formed that a higher TCE initial concentration would result in a higher TCE removal efficiency. In addition, using ENZVIS to degraded TCE-contaminated artificial groundwater has indicated that nitrate and carbonate of groundwater will suppress nanoiron reaction with TCE. Especially, a high concentration of carbonate in the reaction system might form a passive film or precipitates on nanoiron surface. This study further evaluated the treatment efficiency of combining ENZVIS and electrokinetic technology in treating a TCE-contaminated soil. Experimental conditions were given as follows:(1) initial TCE concentration in the range of 98~118 mg/kg; (2) an electric potential gradient of 1 V/cm; (3) a daily addition of 20 mL ENZVIS; and (4) a reaction time of 10 days. Experimental results have shown that an addition of ENZVIS to the anode reservoir of strongly acidic and oxidative environment would cause nanoiron to corrode rapidly and decrease TCE removal efficiency. On the other hand, an addition of ENZVIS to the cathode reservoir would enhance the degradation of TCE therein. In summary, an addition of ENZVIS to the cathod reservoir would yield the best TCE removal efficiency.

Emulsified acids have been extensively used in the oil industry since 1933. Most of the available research and publications discussed mainly the application of emulsified acid in the field. A fair number of the published work also discussed in depth some of the emulsified acid properties such viscosity, stability and reactivity. However, all of the available research discussed the emulsified acid without sufficient details of its preparation. Beside their chemical composition, the ways emulsified acids are prepared cause significant differences in their physical properties. The characterization of emulsified acid by its droplet size and size distribution complements its chemical composition and gives the emulsified acid a unique description and thus reproducible properties. No previous study considered the impact of the droplet size on the characteristics and properties of emulsified acid. Therefore, the main objective of this research is to study the effects of the droplet size on various properties of emulsified acid such as viscosity, stability and reactivity. Results showed that the droplet size and size distribution have a strong effect on the stability, viscosity and diffusion rate of the emulsified acid. The results of this work are important because knowledge of the effect of the droplet size on major design parameters will guide the way emulsified acid is prepared and applied in the field.

The scope of work can be divided into; the measurement of the rheological properties of a new emulsified acid system that can be suitable for high temperature applications, a study of the performance of the new emulsified acid in stimulating both calcite and dolomite formations, measuring the reaction rate and diffusion coefficient when the new emulsified acid systems react with both calcite and dolomite, and testing the new emulsified acid using core samples obtained from carbonate reservoirs. The droplet size has a practical impact on the performance of emulsified acid. A good understanding and characterization of the emulsified acid by its size distribution will lead to better understanding of its stability, rheology and how it reacts with carbonate rocks. The influence of the concentration of the new emulsifier on the droplet size, droplet size distribution and upon the rheology of emulsified acids is studied in detail. The emulsified acid reaction kinetics with calcite rocks was studied before in few studies, and very little work was done with dolomite. One of the main objectives of the present work is to study in detail the reaction of the emulsified acid with both calcite and dolomite rocks using the rotating disk apparatus. Most of the previous studies on the emulsified acid were done using core samples that were saturated with brine or deionized water. One of the main objectives of the present work is to study in detail the effect of the presence of crude oil in the reservoir rock on the performance of emulsified acids. Lastly, an innovative technique of emulsifying the chelating agents is evaluated for high temperature applications. The rheology of the emulsified chelating agent is measured using an HPHT rheometer. Also, the reaction of the new emulsified chelating agent with calcite is studied using the rotating disk apparatus, and coreflood experiments were performed using chelating agents and calcite core samples.

Stearate anions were successfully intercalated into the layered double hydroxide Mg4Al2(OH)12CO3.3H2O (LDH-CO3) by several methods to form LDH-SA. The intercalation method which involved the acid-base reaction between emulsified stearic acid (SA) and the carbonate anions in aqueous media was studied for the first time. This method led to the formation of more LDH-SA than well known methods such as melting the carboxylic acid in the presence of the LDH, allowing the interlayer region to swell in the presence of glycerol and reconstructing the calcined LDH in the presence of aqueous sodium stearate. Other literature methods involve ion-exchange of Cl- in LDH-Cl with stearate in aqueous sodium stearate, usually under N2 atmosphere. The methods developed in this study are more industrially viable because the more easily produced LDH-CO3 is used and no N2 atmosphere is necessary. The LDH-SA was successfully used to intercalate sodium polyvinyl sulphonate by an ion exchange with the intercalated stearate, without the need for a N2 atmosphere. This method of production could be useful for the production of nanocomposites in general, for example anionic polymer chains (such as DNA) and anionic clays. The same intercalation reaction was allowed to take place in situ during the formation of dextrin-alginate-glycerol film solutions in water-ethanol media. The stearate intercalated as a bilayer in the interlayer region of the LDH. The SA to LDH ratio was varied from 100% SA to 100% LDH. Around the middle of the series a minimum water vapour permeability (WVP) was obtained, which corresponded to an 80% reduction in WVP in comparison to the reference (blank) film. Around the middle of the series a maximum increase in Young’s modulus, corresponding to a 213% increase in comparison to the blank film, was obtained. Around the middle of the series a reduction in the intensity of the basal reflection and interlayer distance showed that some exfoliation (delamination) took place. / Thesis (PhD (Chemistry))--University of Pretoria, 2008. / Chemistry / unrestricted

Soil and groundwater at many existing and former industrial areas and disposal sites is contaminated by halogenated organic compounds that were released into the environment. Halogenated organic compounds are heavier than water. When they are released into the subsurface, they tend to adsorb onto the soils and cause the appearance of DNAPL (dense-non-aqueous phase liquid) pool. Among those halogenated organic compounds, trichloroethylene (TCE), a human carcinogen, is one of the commonly observed contaminants in groundwater. Thus, TCE was used as the target compound in this study. The objective of this study was to develop the emulsified carbon-releasing substrate and apply it as the filling material in the permeable reactive barrier to remediate TCE-contaminated groundwater. In this study, the developed emulsified carbon-releasing substrate contained soybean oil, lactate, biodegradable surfactant (Simple GreenTM and lecithin), and nutrients. Results of emulsion test show that up to 90% of the emulsified carbon-releasing substrate was distributed effectively in the soil pores. The emulsified carbon-releasing substrate was able to provide carbon for the enhancement of in situ anaerobic biodegradation for a long period of time. A pilot-scale study was operated at a TCE-contaminated site located in southern Taiwan. Emulsified carbon-releasing substrate emulsion was pressure-injected into the remediation wells. A total of 120 L of emulsified carbon-releasing substrate was injected into the test site. Based on the groundwater analytical results, dissolved oxygen, oxidation-reduction potential, and sulfate concentrations decreased after injection. However, the anaerobic degradation byproduct, acetic acid, increased after injection. Results also show that the total viable bacteria increased in the upgradient injection (remediation) well. Decrease in TCE concentration (dropped to below 0.01 mg/L) was also observed after substrate injection, and TCE degradation byproducts, cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC) were also observed. Result of microbial analyses show that various TCE-degrading bacteria exist in the groundwater samples including Ralstonia sp., Clostridium sp., Uncultured Burkholderiales bacterium, Hydrogenophaga sp., Acidovorax sp., Zoogloea sp., Hydrocarboniphaga sp., Uncultured Curvibacter sp., Pseudomonas sp., Comamonas sp., Aquabacterium sp., and Variovorax strains. This reveals that the anaerobic dechlorination of TCE is a feasible technology at this site. Slug test result show that only a slight variation in soil permeability of the injection well was observed. This indicates that the substrate injection would not cause clogging of the soil pores. Results from the cost analysis show that the total cost for the test site remediation was approximately USD13,442 per year. This indicates that the developed system has the potential to be developed into an environmentally, economically, and naturally acceptable remedial technology. Knowledge obtained from this study will aid in designing a carbon-released substrate biobarrier system for site remediation.

Dissertação(mestrado) - Universidade Federal do Rio Grande, Programa de Pós-Graduação em Engenharia e Ciência de Alimentos, Escola de Química e Alimentos, 2008. / Submitted by Caroline Silva (krol_bilhar@hotmail.com) on 2012-09-24T17:37:34Z No. of bitstreams: 1 dissertao william.pdf: 812854 bytes, checksum: d918ddd99401f9f50f45b002808c68eb (MD5) / Approved for entry into archive by Bruna Vieira(bruninha_vieira@ibest.com.br) on 2012-11-06T22:37:09Z (GMT) No. of bitstreams: 1 dissertao william.pdf: 812854 bytes, checksum: d918ddd99401f9f50f45b002808c68eb (MD5) / Made available in DSpace on 2012-11-06T22:37:09Z (GMT). No. of bitstreams: 1 dissertao william.pdf: 812854 bytes, checksum: d918ddd99401f9f50f45b002808c68eb (MD5) Previous issue date: 2008 / Nas operações de corte e desossa de aves sobra grande quantidade de co-produtos, provenientes de partes menos nobres, cujo valor comercial é menor. Com o propósito de agregar valor aos mesmos, o presente trabalho teve como objetivo desenvolver um processo tecnológico para obtenção de surimi utilizando carne mecanicamente separada de frango, caracterizar o surimi assim obtido e aplicá-lo na elaboração de um embutido emulsionado; e avaliar as propriedades físicas, químicas, microbiológicas e sensoriais que o embutido emulsionado apresenta. A carne mecanicamente separada (CMS) de frango é um co-produto da industrialização do frango, de baixo valor comercial, foi utilizada na elaboração de surimi a partir do método de branqueamento com solução de bicarbonato de sódio e cloreto de sódio. Para isto foi avaliado o efeito de temperatura (T = 2, 7 e 12°C); tempo (t = 5, 10 e 15 minutos/ciclo); e solução de lavagem:CMSF na proporção de (R = 2:1, 4:1 e 6:1 g/g) na obtenção de surimi mediante metodologia de superfície de resposta, sendo as variáveis resposta, proteína e força do gel. A matéria-prima foi caracterizada quanto à composição proximal apresentando 12,9 ± 0,2% de proteína, 18,5± 0,3% de lipídios, 68,1 ± 0,5% de umidade e 0,57 ± 0,06% de cinzas estando dentro dos parâmetros exigidos pelo Ministério da Agricultura e do Abastecimento. A umidade do surimi de frango foi de 89,11 ± 0,46%; a proteína foi 10,74 ± 0,22%. A habilidade de formar gel foi determinada instrumentalmente, apresentando uma força de gel de 646 ± 6 g.cm. No teste de capacidade de dobra, o surimi apresentou as mesmas características de surimi de alta qualidade. O surimi de CMS de frango foi utilizado na elaboração de um embutido emulsionado, e para isto foi avaliado o efeito da proteína de soja, fécula de batata e toucinho na textura do embutido de surimi mediante metodologia de superfície de resposta, sendo as variáveis resposta, força de corte e firmeza. Foram utilizados 5 níveis de cada variável sendo que a proteína de soja variou de 0 a 6%, a fécula de batata de 0 a 10% e toucinho de 2 a 12%. A análise de regressão do modelo mostrou que a proteína texturizada de soja exerce um efeito positivo linear na força de corte do embutido, e que a variável que mais influenciou na firmeza do embutido de surimi de CMS de frango foi a fécula de batata. Os resultados obtidos da análise microbiológica demonstram que estes estavam abaixo dos limites exigidos pela legislação brasileira. A salsicha de surimi de frango teve uma aceitabilidade sensorial de 72,2%. / In the operations of poultry cutting and deboning remains a great amount of co-products from the less noble parts, whose commercial values are lower. With the intention to add value to same the present work aimed to develop a technological process to obtain surimi from mechanically deboned chicken meat (MSCM), to characterize the obtained surimi, apply it in the formulation of an emulsified sausage; and to evaluate the physical, chemical, microbiological and sensorial properties of this product. The MSCM is a coproduct of the chicken industrialization, with low commercial value, and was utilized in the elaboration of surimi using the bleaching method with sodium bicarbonate and sodium chloride solutions. For this purpose, the temperature (T = 2, 7 and 12°C), time (t = 5, 10 and 15 min/cycle) and washing solution:MSCM ratio (R = 2:1, 4:1 and 6:1 g/g) effects were evaluated in the surimi obtaining process by means of the Response Surface Methodology (RSM), being the experimental responses, protein and gel force. The raw material was characterized in function of the proximal composition, presenting 68.1 ± 0.5% of moisture, 12.9 ± 0.2% of protein, 18.5 ± 0.3% of crude lipids, and 0.57 ± 0.06% of ash, which remained according to the Brazilian Ministry of Agriculture, Livestock and Supply. The moisture of the MSCM surimi was 89.11 ± 0.46%; and the protein was 10.74 ± 0.22%. The ability to form gel was instrumentally determined as 646 ± 6 g.cm. The surimi presented the same characteristics of a high quality surimi according to the folding test. MSCM surimi was utilized in the formulation of an emulsified inlaid product, thus, it was evaluated the effects of the soybean protein, potato starch and pig lard on the texture of the emulsified sausage product by means of the RSM, being the experimental responses breaking force and firmness. Five levels of each factor were evaluated: soybean protein varied from 0 to 6%, potato starch from 0 to 10% and lard from 2 to 12%. The regression analysis of the model showed that the soybean texturized protein exerted a linear positive effect in the breaking force of the product, and that the variable that presented the high influence on the firmness the firmness was the potato starch. The microbiological analysis demonstrated that the achieved results were below the limits fixed by the Brazilian Legislation. The MSCM surimi sausage presented 72.2% of acceptability.

Con la finalidad de lograr la estabilización de pavimentos, surgen nuevas tecnologías de agentes estabilizadores como el asfalto espumado y la emulsión asfáltica. En el Proyecto del corredor vial Dv-Humajalso-Desagüadero y Tacna-Capazo-Mazocruz, se tenía como solución técnica aplicar en el Tramo 7 Tarata-Capazo el asfalto espumado. Sin embargo, la condición termodinámica es fundamental para el asfalto espumado y esto se evidencia en el Tramo 7, donde a temperaturas de 5°C en descenso, las partículas de asfalto no se dispersan sobre el mástic, éstas caen sobre otras partículas de asfalto, provocando una aglomeración de asfalto en forma de chicles e imposibilitando la compactación de la capa del pavimento. Frente a esta problemática, se plantea estabilizar el material granular con emulsión asfáltica, donde las partículas de asfalto están dispersas en una solución acuosa a 25°C y no se requiere calentar al asfalto a elevadas temperaturas. El objetivo de la tesis es lograr la estabilización del pavimento utilizando emulsión asfáltica. Para el diseño de la mezcla asfáltica en frío, se utiliza la metodología Illinois y una emulsión catiónica de rotura lenta como ligante. Prosigue, el diseño del pavimento con la metodología AASHTO 93, para determinar los espesores de las capas del pavimento que satisfarán las cargas de tráfico para la vida útil del proyecto. Finalmente, se logra validar la estabilización del pavimento en campo con los controles de compactación y deflectometría, quedando demostrado la versatilidad de la emulsión como mezcla asfáltica en frío frente a las condiciones termodinámicas críticas del Proyecto. / In order to achieve the stabilization of pavements, emerge new technologies of stabilizing agents such as foamed bitumen and asphalt emulsion. In the Roadway Project Dv-Humajalso-Desagüadero and Tacna-Capazo-Mazocruz, the technical solution was to apply foamed bitumen in road Section 7 Tarata-Capazo. Thermodynamic condition is fundamental where foamed bitumen is evidenced in Section 7, the temperature is lower than 5 °C, so the asphalt don’t disperse on the Mastic, causing an agglomeration of asphalt in the form of chewing gum and making impossible the compaction of the pavement layer. In this problem, It’s proposed to stabilize the granular material with asphalt emulsion, so the asphalt particles are dispersed in a solution to 25°C. The technique is a mixture of cold asphalt and is feasible for the critical thermodynamic conditions of the Section 7 Tarata-Capazo. The objective is to achieve the stabilization of the pavement using asphalt emulsion. The design of the cold asphalt mix applies the Illinois Methodology to determine the optimum quantity of residual asphalt. So that, the design of the pavement is done with the methodology of AASHTO 93, which allows to determine the thicknesses of the pavement layers that will satisfy the serviceability and traffic for the useful life of the project. Finally, It´s possible to validate the stabilization of the pavement in the field with the compaction and deflectometry controls, demonstrating the versatility of the emulsion as a cold asphalt mixture against the critical thermodynamic conditions of the Project. / Tesis

Heavy metal contamination of soils, sediments and groundwater presents an ongoing source of hazardous and persistent environmental pollution. How best to remediate these contaminants is the impetus of continuing research efforts. Methods include containment, ex situ and in situ techniques. A successful in situ method utilizing a combination of emulsified liquid membranes, ELM, and zero-valent metal, ZVM, and bimetals has demonstrated impressive heavy metal reduction in 100 ppm solutions of Cd, Cu, Ni, Pb, Cr and U. This promising in situ method has been employed by the Industrial Chemistry Laboratory at the University of Central Florida and it has demonstrated considerable success in treating several environmental threats. Contaminated soils, surfaces, sediments and groundwater with offending agents such as trichloroethene, polychorobiphenyls and heavy metals have been treated utilizing emulsified liquid membrane systems containing zero-valent iron or bimetal particles. In vial studies, lead spiked sediments have shown repeatable 60% removal of lead after seven days of treatment. A persistent pattern emerged at ten days whereupon remediation levels began to drop. The current study was established to determine the reason for the decline at ten days and beyond. Questions addressed: Does the formation of an impeding oxide layer diminish the remediation capacity of the iron/magnesium system? Does the emulsion reach a maximum capacity to withdraw the contaminant? Do the soil components or the soil structure interfere with the access to the contaminant? This study has yielded insight into the reasons emulsified liquid membrane systems containing zero-valent metals achieved maximum lead removal at day seven, and thereafter begin to lose their effectiveness. A three part study was implemented to address and to answer the three questions pertaining to the consistent pattern of diminishing remediation levels exhibited at day ten and beyond. Initially, from Study I results it appeared that the formation of an impeding oxide layer on the bi-metal which was inside the emulsion droplet and which plated or precipitated with the lead was not occurring at day ten. Results indicated that the iron/magnesium was still capable of removing lead. Furthermore, from Study II results the emulsion dose injected appeared adequate to remove the lead, meaning that the emulsion had not reached its maximum capacity for remediation. The emulsion dose was not a limiting factor. Lastly, Study III results seemed to indicate that the drop in remediation after day seven pertained to the soil structure. There appeared to be some merit to the idea that with aging of the sediment, the lead was diffusing and migrating to some inaccessible interior sites within the sediment particles. Additionally, indications from day ten and day fourteen delineated that a second emulsion dose injection might restore lead removal levels to approach those first observed at day seven and consequently be a useful field application. In order to explore the effectiveness of injecting a second dose of emulsion, another vial study was implemented. The typical pattern of observing sixty percent maximum lead removal at day seven was observed. In separate groups, a second injection of emulsion was added at day five, and then for another vial series, a second dose was added at day seven. The second emulsion dose treatment for either day five or day seven did not yield any increases in percent lead removal. Another theory emerged after viewing micrographs of recovered iron/magnesium compared with fresh ball-milled bimetal. In addition, scanning electron microscopy appeared to confirm the explanation that the emulsified zero-valent metal system might be compromised after day seven. This would lead to exposure of the iron/magnesium to the air and the elements. Corrosion of the bimetal might be occurring. With time, release of the plated or precipitated lead back into the sediment mixture could follow. The results of Study I had led to the conclusion that an impeding oxide layer had not formed; however, this conclusion may have been premature because the recovered iron/magnesium was exposed to lead solution in the vial study. Perhaps if the recovered iron/magnesium was inserted back into an emulsion and injected into lead spiked sediments the percent lead removed might give a more accurate picture of the iron/magnesium's capability to continue performing remediation. Remediation of sediments contaminated with lead is a complicated task because of the complex nature of sediment components. Emulsified liquid membranes utilizing zero-valent bimetals has repeatedly demonstrated impressive results at day seven; however, this treatment method is not without its limitations. Optimal results appear to be gained at day seven after emulsion injection. The bimetal and plated or precipitated lead must be removed at that point; otherwise the effective remediation of the contaminant is progressively reversed.