High Metal Content Research Articles

Separation of Indium from Acid Sulfate‐Containing Solutions by Ion Exchange with Impregnated Resins

AbstractIndium separation using ion exchange resins from acidic polymetallic and very diluted solutions are investigated. Since the selectivity of commercial ion exchange resins have proven to be too low for an effective separation from solutions with high content of other metals, Lewatit® TP 208 was impregnated with common extractants to enhance its properties. By resin impregnation with D2EHPA and Cyanex 272, not only the selective indium recovery was reached but also the resin capacity was increased approx. two times. The best loading and elution performance were shown by Cyanex 272‐impregnated Lewatit® TP 208, increasing the indium purity in the eluate from 0.75 % to 85 %.

Effects of Saharan dust cloud water in the remediation of soil having high heavy metal content

Studies revealed that the precipitation from the Saharan Desert brings on a natural fertilizer effect on the plants, contributing to the growth of plants during daytime. In this study, the effectiveness of the Saharan dust has been investigated in the remediation of soil, which has been a very low pH value and high concentrations of various metals. The effects of using the solution obtained by dilution of Saharan dust (as namely Saharan dust water) and Saharan dust on the development of Phaseolus vulgaris and the amount of metal passing to the plant were investigated. It was observed that no plant growth occurred when no remediation was provided on the soil. When metal amounts penetrating the plant was considered, lower metal concentrations were determined in the plants growing with mixtures in which Saharan dust was added and which were irrigated with Saharan dust water compared to mixtures in which compost was added and which were irrigated with Saharan dust water. It was observed that irrigation with Saharan dust water and/or addition of Saharan dust was making the soil suitable for the growth of the plant by increasing its pH in a similar way as adding compost. It was seen that the compost and Saharan dust, and that the solution obtained by Saharan dust water were enabling remediation in soil containing high amounts of metal and having an acidic character at a level as to enable plant growth, and are causing a decrease in the amounts of heavy metal penetrating the plant.

Visbreaking of heavy oil with high metal and asphaltene content

The visbreaking of Canadian oil sands bitumen (OSB) and Tahe atmospheric residue (AR) with high metal and asphaltene content was studied to deepen the understanding of the utilization of ultra-inferior heavy oil. The total content of nickel and vanadium in the asphaltenes contained in Canadian OSB reaches 1300 ppm, promoting large-scale aggregation of asphaltenes. Driven by high asphaltene content of 19.3 wt% and large-scale aggregation of asphaltenes, Canadian OSB with an initial boiling point (IBP) of 500 °C exhibits rapid condensation during visbreaking. Furthermore, those asphaltenes with the highest metal content participate in condensation first, producing metallic nickel in the formed coke. By changing cutting strategy, the group composition and metal distribution of Canadian OSB can be adjusted. A viscosity reduction rate above 99 % is obtained during the visbreaking of Canadian OSB with an IBP of 350 °C, similar to the visbreaking of Tahe AR with an asphaltene content of 15.4 wt% and a total metal content of 300 ppm.

Rancang Bangun Alat Filterasi Limbah Minyak Pelumas (Oli Bekas) Menggunakan Pasir Zeolit, Karbon Altif Dan Membran Keramik

The increasing use of motor vehicles, the greater the amount of engine oil consumption. Engine oil cannot be used continuously due to frictional force on the engine, so engine oil is purified. Unused engine oil can pollute the environment because it is categorized as B3 waste. Used engine oil has a higher metal content than new engine oil. The reduction in metal content can be done by using a filtration column containing zeolite and activated carbon with a filtration column height of 20 cm from each media. Besides filtering also used separation by using a ceramic membrane. In the use of filtration columns filtering used oil using zeolite and activated carbon after that continued using a ceramic membrane, before the used oil is heated at a temperature of 70 0 C then flowed on the ceramic membrane. In this research, a decrease in levels of aluminum (Al), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) was obtained.

Impact of Tellurite on the Metabolism of Paenibacillus pabuli AL109b With Flagellin Production Explaining High Reduction Capacity.

Tellurium (Te) is a metalloid with scarce and scattered abundance but with an increased interest in human activity for its uses in emerging technologies. As is seen for other metals and metalloids, the result of mining activity and improper disposal of high-tech devices will lead to niches with increased abundance of Te. This metalloid will be more available to bacteria and represent an increasing selective pressure. This environmental problem may constitute an opportunity to search for microorganisms with genetic and molecular mechanisms of microbial resistance to Te toxic anions. Organisms from Te-contaminated niches could provide tools for Te remediation and fabrication of Te-containing structures with added value. The objective of this study was to determine the ability of a high metal-resistant Paenibacillus pabuli strain ALJ109b, isolated from high metal content mining residues, to reduce tellurite ion, and to evaluate the formation of metallic tellurium by cellular reduction, isolate the protein responsible, and determine the metabolic response to tellurite during growth. P. pabuli ALJ109b demonstrated to be resistant to Te (IV) at concentrations higher than reported for its genus. It can efficiently remove soluble Te (IV) from solution, over 20% in 8 h of growth, and reduce it to elemental Te, forming monodisperse nanostructures, verified by scattering electron microscopy. Cultivation of P. pabuli ALJ109b in the presence of Te (IV) affected the general protein expression pattern, and hence the metabolism, as demonstrated by high-throughput proteomic analysis. The Te (IV)-induced metabolic shift is characterized by an activation of ROS response. Flagellin from P. pabuli ALJ109b demonstrates high Te (0) forming activity in neutral to basic conditions in a range of temperatures from 20°C to 37°C. In conclusion, the first metabolic characterization of a strain of P. pabuli response to Te (IV) reveals a highly resistant strain with a unique Te (IV) proteomic response. This strain, and its flagellin, display, all the features of potential tools for Te nanoparticle production.

Controlling metallic Co0 in ZIF-67-derived N-C/Co composite catalysts for efficient photocatalytic CO2 reduction

An efficient photocatalytic CO2 reduction has been reported in ZIF-67-derived-Co nanoparticles (NPs) encapsulated in nitrogen-doped carbon layers (N-C/Co). This work demonstrates that the pyrolysis temperature is crucial in tuning the grain size and components of metallic Co0 of N-C/Co composite catalysts, which optimizes their photocatalytic activities. Syntheses were conducted at 600, 700, and 800°C giving the N-C/Co-600, N-C/Co-700, and N-C/Co-800 samples, respectively. N-C layers can well wrap the Co NPs obtained at a low pyrolysis temperature (600°C) owing to their smaller grains than those of other samples. A high metallic Co0 content in the N-C/Co-600 sample can be attributed to the effective inhibition of surface oxidation. By contrast, the surface CoOx oxides in the N-C/Co-700 and N-C/Co-800 samples cover inside Co cores, inhibiting charge separation and transfer. As a result, the N-C/Co-600 sample yields the best photocatalytic activity. The carbon monoxide and hydrogen generation rates are as high as 1.62 × 104 and 2.01 × 104 µmol g−1 h−1, respectively. Additionally, the Co NPs make composite catalysts magnetic, enabling rapid and facile recovery of catalysts with the assistance of an external magnetic field. This work is expected to provide an instructive guideline for designing metal-organic framework-derived carbon/metal composite catalysts.

(216) Kleopatra, a low density critically rotating M-type asteroid

Context. The recent estimates of the 3D shape of the M/Xe-type triple asteroid system (216) Kleopatra indicated a density of ~5 g cm−3, which is by far the highest for a small Solar System body. Such a high density implies a high metal content as well as a low porosity which is not easy to reconcile with its peculiar “dumbbell” shape. Aims. Given the unprecedented angular resolution of the VLT/SPHERE/ZIMPOL camera, here, we aim to constrain the mass (via the characterization of the orbits of the moons) and the shape of (216) Kleopatra with high accuracy, hence its density. Methods. We combined our new VLT/SPHERE observations of (216) Kleopatra recorded during two apparitions in 2017 and 2018 with archival data from the W. M. Keck Observatory, as well as lightcurve, occultation, and delay-Doppler images, to derive a model of its 3D shape using two different algorithms (ADAM, MPCD). Furthermore, an N-body dynamical model allowed us to retrieve the orbital elements of the two moons as explained in the accompanying paper. Results. The shape of (216) Kleopatra is very close to an equilibrium dumbbell figure with two lobes and a thick neck. Its volume equivalent diameter (118.75 ± 1.40) km and mass (2.97 ± 0.32) × 1018 kg (i.e., 56% lower than previously reported) imply a bulk density of (3.38 ± 0.50) g cm−3. Such a low density for a supposedly metal-rich body indicates a substantial porosity within the primary. This porous structure along with its near equilibrium shape is compatible with a formation scenario including a giant impact followed by reaccumulation. (216) Kleopatra’s current rotation period and dumbbell shape imply that it is in a critically rotating state. The low effective gravity along the equator of the body, together with the equatorial orbits of the moons and possibly rubble-pile structure, opens the possibility that the moons formed via mass shedding. Conclusions. (216) Kleopatra is a puzzling multiple system due to the unique characteristics of the primary. This system certainly deserves particular attention in the future, with the Extremely Large Telescopes and possibly a dedicated space mission, to decipher its entire formation history.

Initial Study on Phytoextraction for Recovery of Metals from Sorted and Aged Waste-to-Energy Bottom Ash

Sorted and aged bottom ash from Waste-to-Energy plants, i.e., MIBA (the Mineral fraction of Incinerator Bottom Ash) are potential source of metals that could be utilized to meet the increased demand from society. In this work, sunflowers (Helianthus annuus) and rapeseed (Brassica napus) were cultivated in conventional MIBA to evaluate the possibility for phytoextraction, mainly of Zn, during the period of one cultivation season in the Nordic climate. The results show that metal extraction from MIBA using rapeseed and sunflowers is workable but that neither of the used plants is optimal, mainly due to the inhibited root development and low water- and nutrient-holding capacities of MIBA. The addition of fertilizer is also important for growth. There was a simultaneous accumulation of numerous metals in both plant types, and the highest metal content was generally found in the roots. Calculations indicated that the ash from rapeseed root incineration contained about 2% Zn, and the contents of Co, Cu, and Pb were comparable to those in workable ores. This initial study shows that cultivation in and phytoextraction on MIBA is possible, and that the potential for increased metal extraction is high.

The Catalysis Effect of Na and Point Defect on NO Heterogeneous Adsorption on Carbon during High-Sodium Zhundong Coal Reburning: Structures, Interactions and Thermodynamic Characteristics

The reburning process in a furnace, a key way to reduce NOx emissions, is a heterogeneous reaction during coal combustion, in which the heterogeneous adsorption is dominant. Zhundong coal with a high content of alkali metal can enhance the reburning process. In this paper, the influence of sodium and a defect on NO heterogeneous adsorption was studied by the density functional theory, and the thermodynamic characteristic was also analyzed. The results indicate that the binding energy for NO adsorption on the pristine graphene surface (graphene-NO), Na-decorated pristine graphene surface (graphene-Na-NO), defect graphene surface (gsv-NO) and Na-decorated defect graphene (gsv-Na-NO) is −5.86, −137.12, −48.94 and −74.85 kJ/mol, respectively, and that the heterogeneous adsorption is an exothermic reaction. Furthermore, except for covalent bonds of C and N, C and O for gsv-NO, other interactions are a closed-shell one, based on the analysis of AIM, ELF and IGM. The area of electron localization for NO is graphene-Na-NO > gsv-Na-NO > gsv-NO > graphene-NO. The dispersion interaction is the main interaction force between NO and the pristine graphene surface. The δg index for the atom pairs about N–C and O–C on the pristine graphene surface is also the smallest. The density of spikes at graphene-Na-NO is bigger than that at gsv-Na-NO. Moreover, the thermodynamics characteristic showed that the reaction equilibrium constant of graphene-NO is less than those on the other surfaces under the same temperature. Thus, NO on the pristine graphene surface is the most difficult to adsorb, but the presence of sodium and a defect structure can promote its adsorption.

Steam co-gasification of Japanese cedarwood and its commercial biochar for hydrogen-rich gas production

In this study, steam gasification and co-gasification of Japanese cedarwood and its commercial biochar were performed in a lab-scale fixed-bed reactor to investigate the feasibility for producing H2-rich syngas. Ultimate analysis, proximate analysis, Brunauer-Emmett-Teller (BET) surface area analysis, and scanning electron microscopy (SEM) were conducted to understand the changes caused by the carbonization process. The effects of gasification temperature and steam flow rate on gas production yield from the steam gasification of the individual samples were investigated at first, which showed larger gas production yield and less tar yield for the steam gasification of the commercial biochar than that of raw cedarwood, indicating that the commercial biochar obtained from the carbonization process was more beneficial for the gasification. The co-gasification of raw Japanese cedarwood and its commercial biochar with different mixing ratios was conducted at different reaction temperatures. The synergistic effect was obviously observed. Especially, the commercial biochar with the highly porous structure and high content of alkali and alkaline earth metal (AAEM) species might provide the catalytic effect on cracking and reforming of tar derived from the raw cedarwood, resulting in a larger H2 yield. However, the catalytic effect and gasification reactivity of biochar would decrease by increasing the amount of raw-cedarwood in the blends due to the coke deposition on the surface of biochar.

Differences in the Content of Zn Fractions in the Profiles of Soils from Allotment and Domestic Gardens in South-Eastern Poland

The aim of the research was to show the distribution of fractions as well as bioavailability and the total forms of Zn in the profiles of soils from domestic gardens and family allotment gardens in six cities in south-eastern Poland. Results found that the level of Zn total form varied in the ranges from A horizon: 12.75–154.75 mg·kg−1 in sandy soils and 18.20–104.00 mg·kg−1 in silty soils. Accumulation of metals was assessed using concentration indices, Igeo, and the Cav/Ct and BF indices of bioavailable forms. The analysis took into account the role of organic matter as an important component in binding the analyzed metals in soil horizons subjected to long-term horticultural cultivation. In the two groups of sandy and silty soils distinguished according to their particle size distribution, horticultural treatments were found to exert a greater impact on sandy soils. Additionally, higher contents of the examined element were stated in the humus horizons, as indicated by the high values of concentration and Igeo indices showing high Zn pollution in the soils. The content of bioavailable zinc forms was significantly high, especially in soils with a higher metal content.

Contamination Evaluation of Heavy Metals in a Sediment Core from the Al-Salam Lagoon, Jeddah Coast, Saudi Arabia

The Al-Salam Lagoon is one of the recreational sites along the Jeddah coast, showing the environmental impacts of urbanization along the coast. A sediment core (220 cm) was collected from the intertidal zone to evaluate the heavy metals (Fe, Mn, Cr, Ni, Cu, Zn, and Pb) and geochemical indices (contamination factor, geo-accumulation index, and pollution load index). In the organ-ic-rich muddy sediments (0–100 cm), there is a high metals content and a pollution load index of ~3, indicting anthropogenic impacts with high Cu contamination (CF:12) and moderate Fe, Mn, Cr, Ni, Zn, and Pb contamination (CF: <3). The organic matter and heavy metals washed through surface run-off from the land and deposited as urban waste. Down the core, consistent metals concentration, CF, and Igeo trends indicate a common pollutant source and pollution load variations over time. In the sediment section (70–40 cm), a high organic matter, metal concentration, CF, Igeo, and PLI value (≥5) suggest an uncontrolled pollution load. The decreased and stable trends of environmental indicators toward surface sediments suggest measures taken to control the pollution along the Jeddah coast. Below 110 cm, the carbonate-rich sediments have low organic matter and metals, showing an unpolluted depositional environment. The negative geo-accumulation index implies a geogenic source and indicates no anthropogenic impacts as inferred from low (~1.0) CF and PLI.

Recycling electroplating sludge as a monolithic catalyst for effective catalytic purification of volatile organic compounds

Electroplating sludge had a high content of heavy metals and usually lacked high-value-added utilization. In this work, Cu-containing sludge was used to synthesize a spinel catalyst, which was applied in catalytic oxidization of toluene. As a result, the sludge-derived spinel removed 50% of toluene (1000 ppm, 9600 h−1) at 280 °C. In comparison, a reagent-synthesized spinel with a similar component removed 50% of pollutant at 294 °C. The sludge-derived spinel also showed a stable performance for over 50 h at 370 °C. Even when the initial concentration was increased to 5000 ppm, or the gas hourly space velocity was increased to 40,000 h−1, the temperature for 50% removal was only increased to 303 °C. According to characterizations, surface oxygens of the sludge-derived spinel were more active than those in the reagent-synthesized one. Besides, the former had more active surface oxygens (207.9 μmol/g) than the latter (183.1 μmol/g). Furthermore, the sludge-derived spinel was coated on a monolithic honeycomb, which were also effective in catalytic oxidization of toluene. The main results of this work were in favor of high-value-added utilization of hazardous solid waste and promoting its real industry application.

Phylogenetically divergent bacteria consortium from neutral activated sludge showed heightened potential on bioleaching spent lithium-ion batteries

Recycling of spent lithium-ion batteries (LIBs) has become a global issue because of the potential environment risks raised by spent LIBs as well as high valuable metal content remaining in them. Although bioleaching is an environmentally friendly method to recover metals from spent LIBs, the commonly utilized bioleaching bacterial consortia or strains enriched/isolated from acidic environments cannot be applied at large scales owing to their long leaching cycle and poor tolerance to organic compounds. Here, two bioleaching consortia were enriched in 60 days from neutral activated sludge and were identified phylogenetically divergent from the documented bioleaching bacteria. The results showed that the novel consortia shortened the leaching cycle almost by half when compared to the previous reported consortia or strains, of which one consortium dominated by Acidithiobacillus ferrooxidans displayed high bioleaching efficiency on LiMn2O4, as 69.46% lithium (Li) and 67.60% manganese (Mn) were leached out in seven days. This consortium was further domesticated using cathodic materials for 100 days and proved consisted of three mixotrophs and two chemoautotrophs, three of which were novel species from the genera Sulfobacillus and Leptospirillum. More genes coding for proteins that utilize organic compounds were annotated in the metagenomic assembled genomes (MAGs) than previously reported. A mutualistic relationship between mixotrophs and chemoautotrophs was suggested to help the consortium surviving under either organic- rich or shortage environments. The results discovered that novel bioleaching bacteria with shorter leaching cycle and higher tolerance to organics could be enriched from non-acidic environments, which showed high potential for the metal recovering from spent LIBs or other organic-rich environments.

Surface water quality assessment in the semi-arid area by a combination of heavy metal pollution indices and statistical approaches for sustainable management

The current study consists of evaluating surface water pollution using an integrated approach based on pollution assessment indices and statistical approaches (principal component analysis (PCA), logistic regression (LR) analysis, and cluster analysis (CA)). Thirty-four water samples from the High Ziz basin (semi-arid area), occupied by abandoned mine sites in SE Morocco, were collected and analysed for physicochemical parameters and heavy metals (Cu, Zn, Fe, Pb, Ni, and Cd). The mean concentrations of Pb, Zn, Cu, and Fe in the water samples were 41.9 mg/L, 14.8 mg/L, 20.1 mg/L, and 8.1 mg/L, respectively. The large part of the samples is in a near neutral high metal zone based on the plot of heavy metals (Fe+Cu+Pb+Zn+Ni) versus pH. The HPI, HEI, and CI pollution indices were found to average around 586.2, 321.8, and 315.8 respectively, these show strong correlations with heavy metals. The HPI, CI, and HEI values were above 100 as critical pollution index value. These indices indicate that the surface water samples are critically polluted with respect to studied heavy metals. Therefore, the high metal content of the studied samples should be of great concern for the irrigation activity. Moreover, the water quality index (WQI) shows that 76% of the water samples are unsuitable for drinking. The CA analysis grouped 34 samples into four clusters according to the similarity proprieties observed in water quality. Furthermore, the total variance is explained by 75.7% of the water quality with four components according to PCA analysis. Based on LR analysis, the hazard area is strongly correlated with the river system near abandoned mine sites, agricultural and urban areas. The water quality in the study area is controlled by natural/geogenic processes according to the interpretation of pollution indices and statistical approaches (PCA, CA, and LR). The distribution intensity of Pb, Zn, Cu, and Fe metals in the study area's surface water constitutes an environmental concern and needs a monitoring network for sustainable water resources management.

Effects of heavy metals and organic matter fractions on the fungal communities in mangrove sediments from Techeng Isle, South China

Heavy metal pollution has become a serious environmental problem in mangrove ecosystems and has attracted more attention. Most of previous studies have mainly focused on the effects of heavy metals on bacterial communities in mangrove sediments. This study was the first to investigate the effects of heavy metals (e.g., As, Co, Cr, Cu, Mn, Ni, Pb, V and Zn) and organic matter fractions (including total organic carbon (TOC), total nitrogen (TN), and total sulfur (TS)) on the fungal communities in mangrove sediments from Techeng Isle, South China. The results of this study indicated that the average contents of Mn, Pb and V of 8.30–161.80 μg/g presented relatively higher pollution levels, while the concentrations of Zn, Cr, Cu and Ni of 0.80–21.93 μg/g were lower than those recorded in other mangrove ecosystems. Furthermore, the sediment fungal community structures responded differently to the nine heavy metals and three organic matter fractions. Heavy metals Cr, Pb and V displayed significant positive correlations with Eutypella (P < 0.05), whereas significant negative correlations with Cystobasidium, Lulworthia, Cladosporium, Lulwoana and Cephalotheca (P < 0.05). In addition, the effects of heavy metals and TS on many fungal genera were opposite to those of TOC and TN. Fungal genera that decreased with high TOC and TN contents may be increased with high heavy metal contents and TS, and vice versa, and the genera that increased with high TOC and TN contents may be decreased with high heavy metals and TS. Our results suggested that many heavy metals, such as Cr, Pb and V, were sensitive to several fungal genera in mangrove sediments, and heavy metals together with organic matter fractions may participate and shape the fungal communities in mangrove sediments.

Technologies for metal recycling from electrical - electronic wastes

Wastes from electrical - electronic equipment (WEEE) are of huge concerns worldwide. With the decreasing life cycle of most electrical - electronic equipment (EEE), the WEEE growth rate is fast, about 3÷5% annually. This is considered as the fastest growing waste stream among municipal wastes. WEEE contains, in addition to plastic, glass etc., high contents of base metals and precious metals. They are regarded as potential secondary resources of metals in addition to primary resources of metals from metallic ores. Over the past decades, many metal recycling technologies from WEEE have been developed including physical separation processes and chemical extraction processes. This article summarizes the characteristics, recycling principles, separation processes and optimal operating conditions of the world's most currently common technologies for metal recycling from WEEE. So that one can derive new directions for metal recycling from electrical - electronic wastes in the Vietnam case.

Aging reduces the bioavailability of copper and cadmium in soil immobilized by biochars with various concentrations of endogenous metals

Biochar is widely used for environmental remediation. However, the effects of aging on the bioavailability of trace metals in biochar-amended soil remain largely unknown, especially for the biochars with various concentrations of endogenous metals. In this study, three biochars marked as BB, MB, and HB were produced from the straws of Pennisetum sinese grown in background soil, moderately-, and highly-polluted soils by trace metals, respectively. We distinguished the effects of dry-wet (DW) and freeze-thaw (FT) aging on the bioavailability of copper (Cu) and cadmium (Cd) from soil particles, the biochar interior, and the surface of biochar. The adsorption capacities of Cu2+ and Cd2+ followed the order of BB > MB > HB. DW and FT aging both increased the adsorption capacity of Cu2+, but decreased that of Cd2+ in the three biochars, resulting in a reduction in Cu bioavailability and increase in Cd bioavailability in the biochars after the saturated adsorption of Cu2+ and Cd2+. The incorporation of the three biochars decreased Cu bioavailability compared to the control after incubation for 30d, while the addition of MB increased Cd bioavailability. DW and FT aging decreased Cu bioavailability in biochar-amended soil by decreasing the bioavailability of Cu adsorbed on the biochar surface and immobilized by soil particles. Meanwhile, aging decreased Cd bioavailability by decreasing the bioavailability of Cd immobilized by soil particles. Overall, environmental risk would be increased by the application of biochars with high endogenous Cd. The major implications are that biochar dosage and environmental risk should be carefully assessed before large-scale, continuous application, especially for biochars containing high contents of endogenous trace metals.

Experiments and simulation of the secondary effect during focused Ga ion beam induced deposition of adjacent nanostructures

Focused Ga ion beam can deposit various materials with high-resolution assisted by elaborately selected precursor gases. During the deposition process, the secondary effect arises due to the generation of secondary particles by primary ions. Prominent morphological changes are caused by the secondary effect between adjacent, densely arranged structures. This study analyzes the morphological changes and structural characterizations from the perspective of secondary particles, including scattered ions, sputtered atoms, and re-emitted precursor molecules, with the assistance of continuous cellular automata. C14H10 and W(CO)6 were utilized as the precursor gas in the experiments under the same parameters as the numerical model. The experimental and simulation results demonstrated that the deposit morphology on the adjacent structure, and the enhanced growth rate of the processing structure, could be precisely predicted, with a good estimation of secondary particles contribution. Furthermore, the deposition efficiency on the adjacent structure was improved, and the higher metal content in the deposits was validated by Energy Dispersive X-Ray Spectroscopy (EDS). This work, therefore, lays foundation for avoiding the secondary effect when fabricating nanostructure arrays, and utilizing it for coatings, chiral structure construction, and tuning material properties.

Heavy Metal Potential of Domestic Biological Wastewater Treatment Plant Sludge

The use of sludge as fertilizers helps to the recycling of nutrients to the environment due to its beginning from wastewater and therefore relatively high content of nutrients and organic matter. However, wastewater does also contain hazardous compounds like heavy metals and micro pollutants which eventually are separated to the sludge during the treatment processes at the wastewater treatment plant. In order to improve the sludge quality, source tracking is a relatively cheap and effective way to find and eliminate hazardous compounds and prevent them from ending up in the sludge. The aim with this thesis was to investigate the fertilizer potential in sludge from wastewater treatment plant. The sludge is analyzed in terms of nutrient and heavy metal contents as well as physiochemical parameters. In order to determine the potential as fertilizer, the quality of the sludge is compared with other fertilizer alternatives, other sludge types and regulations for sludge use in agriculture. The work with sludge quality improvements in Gaborone is also investigated. Sludge from different stages along the treatment processes were collected in order to see differences in quality related to the treatment. The results shows that the samples of primary an aerobically treated sludge tend to have higher heavy metal content than the secondary sludge. The quality of the dry sludge samples indicates lower nutrient content than both the primary and secondary sludge, but similar heavy metal content. The analysis of dry sludge from indicates a low nutrient value and high heavy metal content in comparison to other selected fertilizer options and sludge from other. The processes for removal of nutrients from the wastewater are an important factor for the nutrient content in the sludge. Keywords wastewater; fertilizers; nutrients; sludge treatment