Municipal Waste Deposits Research Articles

Preparation and characterization of vitrified tiles from kaolinite clay – waste container glass mixture by sintering method

In this study, vitrified ceramic tiles were made by sintering a mixture of recycled waste container glass powder (RWGP) and kaolinite clays sourced from Nigeria. Initially, waste container glass (transparent color) was obtained from a municipal waste deposit, washed, and crushed before fine milling and sieving to obtain RWGP of approximately 75 µm. Prior to use, the as-received kaolinite clays were also beneficiated and sieved. Three body mixes (VT1, VT2, and VT3) containing 80 – 90 wt. percent RWGP with kaolinite clays and feldspar were homogeneously blended and compacted in a steel mould measuring 200 x 180 x 10 mm. The green compacts were allowed to dry at room temperature before sintering at 1200oC for 2 hours. To evaluate the properties of the developed vitrified tiles, physical, mechanical, phase, and microstructure investigations were carried out. The results showed that bulk density increases across the series, while porosity was 0.5 percent for all tested samples, which is in accordance with ISO 13006. VT2 had higher hardness (6.71 MPa) and compressive strength (2.44 MPa). Quartz and wollastonite were the major phases identified by XRD, with albite, orthoclase, and calcite also present. The microstructure revealed a densified morphology typical of a clay–quartz structure, with little glassy phase resulting from the limited reaction of glass with the clay during sintering.

Assessment of multiple geophysical techniques for the characterization of municipal waste deposit sites

In this study, we tested the ability of geophysical methods to characterize a large technical landfill installed in a former sand quarry. The geophysical surveys specifically aimed at delimitating the deposit site horizontal extension, at estimating its thickness and at characterizing the waste material composition (the moisture content in the present case).The site delimitation was conducted with electromagnetic (in-phase and out-of-phase) and magnetic (vertical gradient and total field) methods that clearly showed the transition between the waste deposit and the host formation.Regarding waste deposit thickness evaluation, electrical resistivity tomography appeared inefficient on this particularly thick deposit site. Thus, we propose a combination of horizontal to vertical noise spectral ratio (HVNSR) and multichannel analysis of the surface waves (MASW), which successfully determined the approximate waste deposit thickness in our test landfill.However, ERT appeared to be an appropriate tool to characterize the moisture content of the waste, which is of prior information for the organic waste biodegradation process.The global multi-scale and multi-method geophysical survey offers precious information for site rehabilitation studies, water content mitigation processes for enhanced biodegradation or landfill mining operation planning.

Improvement in time‐domain induced polarization data quality with multi‐electrode systems by separating current and potential cables

ABSTRACTMeasuring induced polarization in the time domain with relatively compact multi‐channel multi‐electrode systems is attractive because of the simplicity of the procedure and thus its efficiency in the field. However the use of this technique is sometimes discouraged by the bad quality of the measurements in cases of high electrode contact resistances that can render data interpretation infeasible or at least unreliable. It is proposed that capacitive coupling in the multi‐core electrode cables has a significant role in creating this problem.In such cases separation of current and potential circuits by using separate multi‐conductor cable spreads can yield significant improvement in data quality. The procedure is relatively simple and can be implemented with common resistivity and time‐domain IP equipment.We show here three field examples from Southern Sweden, all measured as 2D electrical imaging sections. The first one is an example where the use of a single cable spread is sufficient thanks to moderate electrode contact resistance and high signal levels. The following two examples are from sites where induced polarization measurements could not yield consistent results using only a single multi‐conductor cable spread. Useful results were subsequently obtained by using separate cable spreads.The first example is a 280 m long line measured over an old covered municipal waste deposit where the waste body stands out as a zone of high chargeability. The second example is a 120 m line measured on a sandy glaciofluvial structure that is host to an aquifer of regional importance. The improvement led to discrimination between materials of different grain sizes, with potential bearing for understanding the aquifer. The third example is a 300–400 m line measured across an esker lying on clay till. The improvement led to a clear visualization of the esker and to the identification of a possible fault in the underlying gneissic bedrock.In all cases pseudosections and examples of chargeability decay curves are shown and discussed as tools for assessing data quality. Inversion results are shown together with background geological information and it is concluded that they are in good agreement.

Volatilization of Organotin Species from Municipal Waste Deposits: Novel Species Identification and Modeling of Atmospheric Stability

Organotin compounds are used as pesticides and fungicides as well as additives in plastics. This study identifies the de novo generation of novel volatile organotins in municipal waste deposits and their release via landfill gas. Besides tetramethyltin (Me(4)Sn), a strong neurotoxin, and 5 previously reported organotins, 13 novel ethylated, propylated, and butylated tetraalkyltin compounds were identified. A concentration of 2-4 μg of Sn m(-3) landfill gas was estimated for two landfill sites in Scotland. The atmospheric stability of Me(4)Sn and methylated tin hydrides was determined empirically in a static atmosphere in the dark and under UV light to simulate night- and daytime conditions. Theoretical calculations were carried out to help predict the experimentally obtained stabilities and to estimate the relative stabilities of other alkylated species. Assuming first-order kinetics, the atmospheric half-life for Me(3)SnH was found to be 33 ± 16 and 1311 ± 111 h during day- and nighttime conditions, respectively. Polyalkylation and larger alkyl substitutes tend to reduce the atmospheric stability. These results show that substantial concentrations of neurotoxic organotin compounds can be released from landfill sites and are sufficiently stable in the atmosphere to travel over large distances in night- and daytime conditions to populated areas.

Municipal landfills exhale newly formed organotins

For the first time we are able to report the identification and quantification of several unexpected alkylated tin compounds such as dimethyldiethyltin, trimethylethyltin and propyltrimethyltin in European municipal waste deposits, by using GC-ICP-MS. Future studies will reveal whether their origin is from the degradation of butyl-, or octyltin compounds or simply products of de novo synthesis within the landfill environment.

Environmental Properties of Minerals and Contaminants Purified by the Mineralogical Method

Abstract The investigation of the environmental properties of minerals, i.e., environmental mineralogy, is a branch of science dealing with interactions between natural minerals and spheres of the Earth surface as well as a reflection of global change, prevention of ecological destruction, participation in biomineralogy, and remediation of environmental pollution. Pollutant treatment by natural minerals is based on the natural law and reflects natural self‐purification functions in the inorganic world, similar to that of the organic world — a biological treatment. A series of case studies related to natural self‐purification, which were mostly completed by our group, are discussed in this paper. In natural cryptomelane there is a larger pseudotetragonal tunnel than that formed by [MnO6] octahedral double chains, with an aperture of 0.462–0.466 nm2, filled with K cations. Cryptomelane might be a real naturally‐occurring mineral of the active octahedral molecular sieve (OMS‐2). CrVI‐bearing wastewater can be treated by natural pyrrhotite, which is used as a reductant to reduce CrVI and as a precipitant to precipitate CrIII simultaneously. Batch experiments were conducted using the CTMAB‐Montmorillonite as an adsorbent for aromatic contaminants (phenol, aniline, benzene, toluene and xylenes), which are detected frequently in the leaching water from municipal waste deposits around China. The CTMAB modification has proved very effective to enhance the adsorption capacity of the sorbent. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside briquettes, and thus brings enough oxygen for combustion and the sulfation reaction. Effective combustion of the original carbon reduces the amount of dust in the fly ash.

Leachate treatment by the combination of photochemical oxidation with biological process

Leachates are well known as a particular sort of problematic wastewater, both from the viewpoint of ecotoxicity and the treatment technique. Leachates from municipal waste deposits, biologically pre-cleaned, were treated subsequently by photochemical oxidation using three different UV sources. The reactor concept was based on a ‘continuous circuit reactor’ with back-mixing and thin film. The power was 84 kW/m 3 for the low pressure mercury lamp, 100 kW/m 3 for the middle pressure mercury lamp, and 30 kW/m 3 for the vacuum mercury lamp. The ratio of chemical oxygen demand (COD) and BOD 5 was reduced from ca. 230 to 3–4 (in the case of low pressure and vacuum mercury lamp) and to 6 (middle pressure mercury lamp). After the photochemical oxidation stage, the leachate was treated in an additional step using an activated sludge plant. After this biological stage, the values of COD, BOD, and AOX decreased further below the threshold values defined in the legislative regulation. The Ames-, umu-, and alkaline filter elution-tests were applied at all treatment stages. The treated water, independent on treatment stage, proved to be free of mutagens. The luminescent bacteria—green algae—as well as Daphnia-test were applied for each of the individual treatment stages.

Retention of inorganic pollutants in clayey base sealings of municipal landfills

The 10-year-old base sealing of a municipal waste deposit near Horn, located in the Austrian part of the Bohemian Massif, was examined by mineralogical and geochemical methods. The objective of this study was to measure its retention capability with respect to selected inorganic pollutants, especially heavy metals. The mineralogical results show a homogeneous composition of the base sealing, which consists of clay dominated by kaolinite. In the Bohemian Massif, this pattern is typical for products of weathered rocks, which were originally rich in feldspar. The hydraulic conductivity is very low ( k f≈1×10 −11 m s −1). Geochemical analyses show that heavy metals like Pb, Cu, Zn and Cd are concentrated in the uppermost parts of the sealing. Only a few centimeters below, the concentrations of these elements are at the geochemical background level. Anionic contaminants, however, are found in greater depth due to an almost nonexistent adsorption on the clay. This is the reason why they were used as tracers for further research on diffusion processes (apparent diffusion coefficient of chloride D a,Cl=2.6×10 −10 m 2 s −1). Detailed studies of the behavior of Cu, Pb, Zn and Cd were performed using sorption tests (diffusion and batch tests) and sequential extraction methods. From the diffusion experiments, breakthrough times of some heavy metal ions were evaluated for the actual thickness of the sealing. There were Zn >200 years and Pb >700 years. These times can be considered as “worst case” examples which give good indications of the retention capability of the sealing. The results clearly demonstrate that even after a period of 10 years of contact with contaminated landfill leachates, the clayey liner had fulfilled the requirements of retaining heavy metals. Furthermore, the base sealing was far from reaching the limits of its retention capacity.

A new HG/LT-GC/ICP-MS multi-element speciation technique for real samples in different matrices.

An improved speciation technique is presented for metal(loid)organic compounds, enabling identification and quantification of species from twelve elements: germanium, arsenic, selenium, molybdenum, tin, antimony, tellurium, iodine, tungsten, mercury, lead and bismuth. At this time it is possible to identify 29 species with boiling points between -88.5 degrees C and 250 C in gaseous, liquid and solid samples in a few minutes. This study shows as an example results from measurements of soil samples from municipal waste deposits. The HG/LT-GC/ICP-MS-(hydride generation/low temperature-gas chromatography/inductively coupled plasma-mass spectrometry) apparatus contains a home-built gas chromatograph that enables satisfactory separation of various species with a boiling point difference of > or = 14 degrees C. The absolute detection limits for the elements mentioned above were below 0.7 pg.

Avaliação ambiental dos resíduos produzidos pelas empresas metalúrgicas localizadas no perímetro urbano da cidade de Ijuí

The present work has as its main objective the assessment of the kind and quantity of waste produced by the metallurgic industries in the city of Ijuí. The roll of the 78 metallurgic plants was drawn from the ROLL OF CONTRIBUTORS/96 provided by the BUREAU OF COMERCE, INDUSTRY ANO TOURISM OF IJUÍ. In spite of this number, only 40 firms were assessed because the others were closed (14) or not found (24). The assessment was made through a questionnaire applied IN LOCO in a period comprised between June/96 to February/97. The numeric data about the amount of waste is a monthly average value estimated by the firms themselves. The waste produced in higher amounts are: metals, fusing sand, office paper and dining hall scraps. The total amount of waste produced makes 48.809 Kg/month, being 14.711 Kg/month are reciclated. The waste not recycled makes 34.098 Kg/month and is sent to junk yards, burnt or thrown in the municipal waste deposit 101. The fusing sand, wich is the waste produced in major amounts of size, isn't produced anymore. In this case the total amount of waste produced goes to 18.809 Kg/month, with a recycling percentage of 78%

Occurrence of Volatile Transition Metal Compounds in Landfill Gas: Synthesis of Molybdenum and Tungsten Carbonyls in the Environment

Evidence for the occurrence of volatile molybdenum and tungsten compounds in the environment is presented for the first time. The gases from three different municipal waste deposits were sampled and analyzed for volatile metal and metalloid compounds by using gas chromatography coupled with inductively-coupled plasma mass spectrometry (GC−ICP−MS). In addition to the known hydrides and methylated compounds of As, Se, Sn, Sb, Te, Hg, Pb and Bi, volatile Mo and W compounds were found in concentrations of about 0.2−0.3 μg of Mo/m3 and 0.005−0.01 μg of W/m3. The isotopic fingerprint of the detected Mo and W from the samples matched perfectly with Mo and W standards. The correspondence of the samples' retention times (GC−ICP−MS) with those of standards provides convincing evidence that Mo(CO)6 and W(CO)6 are present in landfill gas. The toxicity and origin of these compounds are discussed.

Volatile metal and metalloid species in gases from municipal waste deposits

AbstractWe have detected volatile species of silicon, vanadium, arsenic, bromine, tin, antimony, tellurium, iodine, mercury, lead and bismuth in gases released from domestic waste deposits, using inductively coupled argon plasma mass spectrometry (ICP MS). By concurrent aspiration of a multielement standard solution for calibration, the element concentrations in deposit gas are found to be in the range from 0.1 ng m−3 to 10 μg m−3 gas. The global amount of some metal species emitted by this process may be of the order of several tons per year. These results suggest a biogeochemical pathway for the transfer of metals into the atmosphere via volatile species. This process may have significant influence on atmospheric cycling of metals as well as on metal toxicity within ecosystems.