The overall objective of this thesis is to better understand and assess pesticide leaching at the regional scale, using both the analysis of monitoring data and spatially distributed modelling. Atrazine contamination of the Brusselian aquifer (central Belgium) is poorly understood. Considerable uncertainty surrounds whether the pollution is agricultural or non-agricultural in origin. The spatial and temporal covariance of atrazine concentrations was studied by fitting semivariogram models to monitoring data. Correlation ranges were found to be 600 metres and 600-700 days. A non-parametric one-way ANOVA found a strong relationship between mean concentrations and land use, whilst other environmental variables were found to be less important. Higher levels of pollution were detected in areas dominated by urban land use suggesting that atrazine residues in groundwater resulted from non-agricultural applications. Modelling pesticide leaching at the regional scale (Dyle catchment) was used to assess groundwater vulnerability. Different approaches to process soil information were tested with both a linear (modified Attenuation Factor) and a non-linear (GeoPEARL) leaching model. The CI (calculate first, interpolate later) and IC (interpolate first, calculate later) approaches were identical for the linear model, but differences in the amount of leaching were found for the non-linear model. The CI approach would be expected to give better results than IC, but the CA (calculate alone) approach is probably the best method if no spatial output is required. Finally, a methodology was developed to quantify the uncertainty arising from the spatial variability of non-georeferenced parameters (i.e. those assumed to be spatially constant in deterministic simulations). A Monte Carlo analysis of atrazine leaching was performed with six pesticide and soil properties as uncertain inputs. Spatial variability of non-georeferenced parameters had a significant influence on the amount of simulated leaching. In the stochastic simulation, concentrations exist above the regulatory level of 0.1 µg/L, while virtually no leaching occurred in the deterministic simulation. Including the spatial variability of substance parameters (half-life, sorption coefficient...) would have significant consequences for future registration policies, especially if risk assessments are implemented in a spatially distributed way.

Arsenic (As) poses a significant water quality problem and it is a big challenge for all coal-based power plant industries worldwide. Currently most of the researches on the leaching behavior of arsenic from fly ash are based on the titration experiments. In this study a simulation method is used to study on the pH effect on the arsenic separation of coal-based power plants. Both single point and composition survey simulation of the OLI stream analyzer are used in the study. The simulation results of single point calculation indicates that for the fly ash which has high lime weight percent and equilibrium fly ash solution pH is over 11 and between 7 and 9, that is, Type C fly ash, the simulation results for equilibrium pH in fly ash solutions have great accuracy compared to actual experiment results. Based on the results obtained from single point simulation, both acid and base titrations of composition survey are simulated and the output results suggest that for the same type of fly ash, the simulation results proves the general trend of arsenic solubility in fly ash solutions. The solubility of arsenic decreases with the increase of pH value. It is also noted that at the equilibrium pH fly ash solutions, the maximum solid/liquid ratio of arsenic concentration is observed for type C fly ash. For other fly ashes which have low lime weight percent, the simulation results have discrepancy compared to actual experiment results. This work is important in offering an alternative way of analyze the reasonable output species and relative concentrations for type C fly ash in the waste water storage pond under specific pH conditions, which can be of great importance for the power plants to monitor and minimize the environment pollution in order to meet the future federal regulations.

Printed Circuit Board (PCB) industry is one of the two major Integrated Circuit (IC) part manufacturing industries in Taiwan, but it derives many environmental problems because large amount of chemicals and special materials are used in its process, especially copper sludge generated from wastewater treatment. Although the heavy metal sludge can be treated by solidification, heavy metals contained in the sludge may still be leached out due to longtime exposure to acid rain. Therefore, there are urgent needs of research and development of technologies regarding how to reduce both quantity and volume of the hazardous heavy metal sludge and how to recycle the valuable heavy metals. Acid leaching method, chemical exchange method and ferrite process are applied to study how to recycle and stabilize copper sludge of PCB industry. The ultimate goal is to achieve cleaning production and sustainable development by transforming the hazardous waste into valuable byproducts, reducing the amount of the waste and lowering the treatment costs. Experimental results show that a method is successfully developed to recycle copper from the sludge generated by PCB industry by using the combination of acid leaching, chemical exchange and ferrite process. Via this method, not only is pure copper powder recycled, but highly valuable nano-scaled catalyst-CuFe2O4 is also produced. Hence, the problem that copper sludge has nowhere to go is solved, as well as the high cost of catalyst in catalytic incineration is reduced to nearly zero. The achievements of this study are summarized as follow: (1) Characteristic analysis of industrial sludge Water content and pH of the sludge is 60% and 7.05, respectively. The drop in quantity of ignition is 23%. The screening test results show that particle size of the sludge varies from 0.4 £gm to 200 £gm, with D50 of 25.0 £gm. Cu, Pb, Cd, Zn, Ni and Cr are found in the sludge, and the biggest part of heavy metals is Cu, with a concentration of 158,000 mg/kg (dry basis), whereas the other heavy metals are all below 105 mg/kg (dry basis). (2) Study of recycling of pure copper powder The optimal operational condition of acid leaching method is that concentration of sulfuric acid is 2.0 N, temperature is 50¢J and treatment time is 60 minutes. Under this operational condition, more than 99% of heavy metals can be extracted to liquid phase and the sediment of treated sludge meet Toxicity Characteristic Leaching Procedure (TCLP) standards and therefore is considered as general industrial waste. The optimal operational condition of chemical exchange method is that molar ratio of Fe/Cu is 5.0, pH is 2.0 and treatment temperature is 50¢J. Under this operational condition, more than 95.0% of Cu can be recovered. The optimal operational condition of ferrite process is that Fe/Cu=10.0, pH=9.0, treatment temperature=80¢J, aeration rate=3 L/min/per liter waste liquid and reaction time = 30 min. Under this operational condition, TCLP concentrations of all heavy metals of both supernatant and sludge are well below regulatory standards, which proves that ferrite process is very effective. (3) Resourcing of spinel sludge In the potential of catalytic incineration of volatile organic compounds test, the sludge generated from ferrite process is used to catalyze the isopropyl alcohol (IPA). The catalyst is replaced by the same volume of glass wool on a reactive bed as a blank. Experimental result shows that the conversion of IPA is only 10% at 200¢J and 75% at 500¢J in the absence of catalyst under the conditions that IPA inlet concentration=1,700 ppm, space velocity=24,000 hr-1, O2 concentration=21%, and relative humidity=19%, which indicates that the destruction of IPA is associated with the consumption of much energy when no catalyst was used. But when ferrite catalyst is applied, IPA is decomposed completely at 200¢J, showing that the sludge has great potential of catalyst. (4) Synthesizing five VOCs catalyzing ferrite catalysts via ferrite process As to the synthesis of five ferrite catalysts in the laboratory, IPA conversion rate is higher than 58% at 200¢J. The sequence of IPA conversion from good to bad is Cu-ferrite catalyst > Mn-ferrite catalyst > Ni-ferrite catalyst > Zn-ferrite catalyst > Cr-ferrite catalyst, where Cu/Fe is most efficiency, with IPA conversion rate of 75% at 150¢J and 100% at 200¢J.

No description available.

Most of the city of Uppsala rests on postglacial clay with a varying content of sulphur. The sulphur occurs naturally in the clay in reduced form as sulphide and the clay is for that reason usually called “sulphide clay”. Excavation during construction activities gives rise to large amounts of excavation material, of which the sulphide clay is a considerable part. When the clay is exposed to air and water, an oxidation of the sulphides occurs which may produce an acid leachate and the mobilisation of heavy metals bound in the clay or underlying material. The aim of the work has been to improve our understanding of the behaviour of sulphide clays and produce a basis for risk assessment in the future handling of excavation material with high sulphide content. After sampling had been carried out in two places, batch tests were performed to examine the long-term acidification potential of clays with different calcium carbonate content. The tests were performed with continuous air supply and during the experiment leachate water was analysed with respect to pH, alkalinity, dissolved sulphate and mobilised metals. The results from the laboratory study showed that a clay with a high calcium carbonate content and thus a high net neutralisation potential (NNP) will consume the generated acid and prevent against a lowering of the pH. In clay lacking calcium carbonate, the pH dropped significantly and caused a mobilisation of chiefly Cd, Mn, Co, Ni, Ca and As. Regardless of the changes in pH over time, a large production of sulphur was observed as a result of the sulphide oxidation. In a risk assessment, it is suggested that the NNP should be determined by methods agreed upon to facilitate future comparisons and because different methods may give different results. A clay with a NNP<5 kg CaCO3/ton should be further analysed with respect to metal content to establish the leachate generation potential and estimate the future environmental influence of the excavation material. / Uppsala stad vilar till stor del på postglacial lera med varierande svavelhalt. Svavlet finns naturligt i leran i reducerad form som sulfid och leran kallas därför vanligtvis för ”sulfidlera”. Vid schaktningsarbete i samband med byggnation uppkommer stora mängder schaktmassor varav en betydande del är sulfidlera. Då leran exponeras för luft och nederbörd sker en oxidation av sulfiderna som kan ge upphov till surt lakvatten och läckage av tungmetaller bundna i leran eller underliggande material. Syftet med arbetet har varit att öka kunskaperna om hur sulfidleror beter sig och ta fram ett underlag för riskbedömning i samband med den framtida hanteringen av sulfidhaltiga schaktmassor i Uppsala. Efter genomförd provtagning på två platser utfördes skaktest för att undersöka den långsiktiga försurningspotentialen hos lera med varierande kalkinnehåll. Testerna utfördes med kontinuerlig tillförsel av luft och löpande under försökets gång togs lakvatten ut för analys avseende pH, alkalinitet, löst sulfat och utlakade metaller. Resultaten från den laborativa studien visade att en kalkhaltig lera med hög nettoneutralisationspotential (NNP) kan förbruka den bildade syran och därigenom genereras ingen pH-sänkning. I lera som saknar kalk sjönk pH kraftigt och föranledde läckage av framförallt Cd, Mn, Co, Ni, Ca och As. Oavsett utvecklingen av pH observerades en stor utlakning av svavel till följd av oxidationen av sulfider. I en riskbedömning föreslås att lerans NNP bestäms enligt överenskomna metoder för att underlätta framtida jämförelser och för att olika tekniker kan ge olika resultat. En lera med NNP-värde < 5 kg CaCO3/ton bör analyseras vidare avseende metallinnehåll för att fastställa den potentiella utlakningen och bedöma schaktmassans framtida naturpåverkan.

An approach to arsenic and selenium removal from fly ash is studied. This research includes a comparison of the leaching ability of ammonium oxalate, ammonium citrate, ammonium nitrate and EDTA to extract arsenic and selenium; use of common agricultural waste as a source of oxalate anion to remove arsenic and selenium from fly ash and estimation of additional calcium effects on arsenic and selenium leaching behaviors. This research shows that extraction strength order is EDTA > ammonium oxalate > ammonium citrate > ammonium nitrate > water, achieving arsenic extraction efficiencies of 94.18%, 84.17%, 4.50%, 2.89% and 0.18%, respectively; achieving selenium extraction efficiencies of 96.14%, 96.26%, 84.34%, 26.60% and 0.71%,respectively, in single-stage extraction. Tall fescue is applied as a source of natural oxalate resource and is able to remove over 70% of arsenic and selenium from fly ash. Additional calcium is found to make 82.20% of total arsenic in free oxalate leachate drop to 1.65% of total arsenic in free oxalate and free calcium leachate. All samples were analyzed using HG-AFS. Hopefully, this research will be helpful when a large scale, cheap and sustainable fly ash clean-up approach is needed for power plants prior to landfilling. Also, calcium effects will enable arsenic and selenium to move to the solid phase and could possibly solve the problem of toxic wastewater generated from the clean-up process. The enriched toxic solid waste could be used for pesticide applications.

Incineration of waste is increasing in the EU. However, in the incineration process, both fly and bottom ash materials are generated as waste that requires further action. A common goal throughout Europe is to find ways to utilize ash materials in an environmentally and economically efficient manner in accordance with the current legislation. This legislation is the Waste Framework Directive (WFD) which lists essential properties (H-criteria) to classify waste, as hazardous or not. Of these criteria, ecotoxicity (H-14) should be classified based on the wastes’ inherent hazardous properties. The WFD further states that this classification should be based on the Community legislation on chemicals (the CLP Regulation). Today, there are no harmonized quantitative criteria for the H-14 classification in the WFD, but there is a proposal from the EU on a computing model that summarizes all the measured elements classified as ecotoxic in the solid material. However, there may be a poor relationship between the theoretical ecotoxicity, based on analysed individual elements, and their actual contribution to the measured total toxicity. Therefore, to reduce the risk of incorrectly assessing the hazard potential, the overall aim of this doctoral Thesis was to develop a scientifically well-founded basis for the choice of leaching methodology and ecotoxicity testing for the H-14 classification of ash materials in Europe. In Paper I, different ash materials were classified, two leaching methods were compared and the sensitivity as well as the usefulness of a selected number of aquatic ecotoxicity tests were evaluated. Paper III and IV studied different leaching conditions, relevant for both hazard classification and risk evaluation of ash. Moreover, all four papers investigated potentially causative ecotoxic elements in the ash leachates. The results from this Thesis show that elements not classified as ecotoxic in the chemical legislation have a significant influence on the overall toxicity of the complex ash materials and will be considered if using the approach with ecotoxicity tests on ash leachates, but not if using the computing model. In addition, the approach of comparing chemically analysed elements in the solid ash with literature toxicity data for the same elements systematically over-estimates the hazard potential. This emphasizes the importance of using leaching tests in combination with ecotoxicity tests for the ecotoxicity classification of ash materials, at least if the aim is to fully understand the inherent hazard potential of the ash. To conclude, the recommendation for H-14 classification of ash is that leachates should be prepared using the leaching test and conditions evaluated in Paper III and that the generated leachates should be tested in a battery of test organisms representing a wide range of biological variation and different routes of exposure. This classification proposal has support in the CLP Regulation and contributes to harmonizing the waste and chemical legislation. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>

In this thesis work, a high grade chromite concentrate obtained from PinarbaSi, Kayseri region of Turkey was reacted with sulfuric acid solution to determine the optimum conditions of leaching of chromite ores. Conventional methods for producing chromium are still valid in industry. The main process in production includes soda melting and taking it into solution in the form of chemical compounds such as sodium dichromate. Three and six valence states of chromium have importance in production. Trivalent chromium, chrome ore or chromite have no harmful effects. However, compounds of hexavalent chromium show toxic, irritating and corrosive action to people and environment. In the mentioned conventional method, main products consist of hexavalent chromium compounds. In this study, only trivalent chromium remained in the leach solution and did not change to hexavalent state. Obtained product after leaching was chromium(III) sulfate. The maximum extraction of chromium in the absence of perchloric acid was 94.1 % under the conditions of 175 &deg / C, 6 hours and 84.6 wt % sulfuric acid. The maximum extraction of chromium in the presence of perchloric acid was 98.7 % under the conditions of 175 &deg / C, 2 hours, 84.6 wt % sulfuric acid and &frac12 / perchloric acid / chromite ratio. The latter one was also the highest recovery value obtained during the experiments. Moreover, in none of the analyzed samples, appreciable amounts of hexavalent chromium was found during analyses.

In this study, an attempt has been made to hydrometallurgical extraction of cobalt and nickel by atmospheric pressure sulphuric acid leaching and a pug-roast-leach process using two stage roasting for lateritic ore. The ore used in the study was obtained from &Ccedil / aldag Lateritic Ore, Manisa, Turkey. The metal contents of the ore are 2.1 % Ni, 0.12 % Co, 32.45 % Fe, 1.01 % Mn, 2.58 % Cr, 0.78 % Mg and 1.01 % Al. The reserve of lateritic ore deposit is approximately 40 million tonnes. In the study, first sulphuric acid leaching was applied at atmospheric pressure for leaching the &Ccedil / aldag lateritic ore. The effect of various parameters, such as leaching time, leaching temperature, particle size, pulp density and acid strength on Ni and Co extractions were determined. By leaching at 80oC for 40 wt % H2SO4 addition of ore, 1/3 pulp density, Ni and Co extractions were found 44.49 % and 53.03 % respectively, yielded a pregnant solution containing 3.11 g/L Ni and 0.12 g/L Co. But the result of atmospheric pressure sulphuric acid leaching was considered insufficient from the recovery point of view. In the pug-roast-leach process, which is consisted of a two stage roasting followed by water leaching, decomposition temperature differences of sulphates of cobalt, nickel and iron are exploited. In this process, amount of acid, sulphatization and decomposition temperature, sulphatization and decomposition time, leaching temperature and time, solid/liquid ratio, and the effect of water addition during pugging were optimized. Under the optimized conditions (sulphuric acid: 25 wt % of ore / moisture: 20 wt % of ore / sulphatization temperature: 450oC / sulphatization time: 30 minutes / decomposition temperature: 700oC / decomposition time: 60 minutes / leaching temperature: 70oC / leaching time: 30 minutes and solid-liquid ratio: 1/4 by weight), Co and Ni extractions were found 91.4 and 84.4 percent, respectively. A pregnant solution containing 3.084 g/L Ni and 0.185 g/L Co was obtained. These results were considered sufficient for the leaching of lateritic nickel ores.

Titanium diboride was produced both by volume combustion synthesis (VCS) and by mechanochemical synthesis through the reaction of TiO2, B2O3 and metallic Mg. Reaction products were expected to be composed of TiB2 and MgO. However, side products such as Mg2TiO4, Mg3B2O6, MgB2 and TiN were also present in the products obtained by volume combustion synthesis. Formation of TiN could be prevented by conducting the volume combustion synthesis under argon atmosphere. Mg2TiO4 did not form when 40% excess Mg was used. Wet ball milling of the products before leaching was found to be effective in removal of Mg3B2O6 during leaching in 1M HCl. When stoichiometric starting mixtures were used, all of the side products could be removed after wet ball milling in ethanol and leaching in 5 M HCl. Thus, pure TiB2 was obtained with a molar yield of 30%. Pure TiB2 could also be obtained at a molar yield of 45.6% by hot leaching of VCS products at 75oC in 5 M HCl, omitting the wet ball milling step. By mechanochemical processing, products containing only TiB2 and MgO were obtained after 15 hours of ball milling. Leaching in 0.5 M HCl for 3 minutes was found to be sufficient for elimination of MgO. Molar yield of TiB2 was 89.6%, much higher than that of TiB2 produced by volume combustion synthesis. According to scanning electron microscope analyses, produced TiB2 had average particle size of 0.27&plusmn / 0.08 &amp / #956 / m.