Settlement Prediction for Municipal Solid Waste Landfills Using Power Creep Law

One of the most important factors that affect the post-closure operation of a landfill is the settlement of refuse and foundation material. Prediction of settlement of refuse is complex because of the mechanisms of settlement and the heterogeneity of the refuse. The settlement of a landfill can be estimated using a simplified method, the Power Creep Law. Based on the analysis of published data measured in the field from four landfills, a correlation is proposed between two parameters, reference compressibility and rate of compression, required to predict the refuse settlement using the Power Creep Law. The settlement-time relationships of waste landfills predicted using the proposed correlation show better agreement with the measured settlements than the settlements predicted using average values or some arbitrary combination of the parameters.     

Mineralization in Ferritin: An Efficient Means of Iron Storage

Ferritins are a class of iron storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. Iron is stored within the protein shell of ferritin as a hydrous ferric oxide nanoparticle with a structure similar to that of the mineral "ferrihydrite." The eight hydrophilic channels that traverse the protein shell are thought to be the primary avenues by which iron gains entry to the interior of eukaryotic ferritins. Twenty-four subunits constitute the protein shell and, in mammalian ferritins, are of two types, H and L, which have complementary functions in iron uptake. The H chain contains a dinuclear ferroxidase site that is located within the four-helix bundle of the subunit; it catalyzes the oxidation of ferrous iron by O(2), producing H(2)O(2). The L subunit lacks this site but contains additional glutamate residues on the interior surface of the protein shell which produce a microenvironment that facilitates mineralization and the turnover of iron(III) at the H subunit ferroxidase site. Recent spectroscopic studies have shown that a di-Fe(III) peroxo intermediate is produced at the ferroxidase site followed by formation of a mu-oxobridged dimer, which then fragments and migrates to the nucleation sites to form incipient mineral core species. Once sufficient core has developed, iron oxidation and mineralization occur primarily on the surface of the growing crystallite, thus minimizing the production of potentially harmful H(2)O(2).     

A Comparison of the Rates of Fe(III) Reduction in Synthetic and Bacteriogenic Iron Oxides by Shewanella putrefaciens CN32

The susceptibility of various bacteriogenic iron oxides (BIOS) to bacterial Fe(III) reduction was examined. Reduction resulted in complete dissolution of the iron mineral from the surfaces of the Fe-oxidizing consortium. Reduction rates were compared to that of synthetic ferrihydrite (HFO). The reduction rate of HFO (0.162 day^{? 1}) was significantly lower than that of Äspö (Gallionella dominated) BIOS (0.269 day^{? 1}). Two Canadian (Leptothrix dominated) BIOS samples showed statistically equivalent rates of reduction (0.541 day^?1 and 0.467 day^{? 1}), which were higher than both Äspö BIOS and HFO. BIOS produced by different iron-oxidizing genera have different susceptibilities to microbial reduction.     

Metal Leaching and Reductive Dissolution of Iron from Contaminated Soil and Sediment Samples by Indigenous Bacteria and Bacillus Isolates

The purpose of this study was to leach Cu, Zn, As, and Fe from contaminated soil and sediment samples with indigenous heterotrophic bacteria isolated from the study sites. The sediment contained Fe in the form of goethite and low concentrations of other metals. The soil contained hematite and high concentrations of other metals. The environmental conditions affected the bacterial activity in the metals dissolution. As and Fe were the major metals leached from the sediment sample while a minor fraction of Cu was solubilized. Cu and Zn were the major metals leached from the soil sample while only a minor fraction of Fe was dissolved. As a control, a disinfectant was used for partial inactivation of indigenous bacteria. This treatment had a negative effect on the leaching of Fe, Zn and As from soil and sediment samples, but it increased Cu dissolution from the sediment. Bacterial different dissolution of Fe during soil and sediment bioleaching was also investigated with ferrihydrite. The iron concentration was much higher during ferrihydrite dissolution when indigenous bacteria from sediment were used compared to indigenous bacteria isolated from soil. The indigenous bacterial inoculum provided more biological and metabolic diversity which may account for the difference in reductive iron reduction from ferrihydrite. The Bacillus cultures isolated from soil and sediment samples showed similar efficiencies in reductive dissolution of ferrihydrite. The synergetic bacterial inhibition effect created by the environmental conditions can influence bioremediation effect.     

Life Cycle Management of Municipal Solid Waste

Life-cycle assessment concepts and methods are currently being applied to evaluate integrated municipal solid waste management strategies throughout the world. The Research Triangle Institute and the U.S. Environmental Protection Agency are working to develop a computer-based decision support tool to evaluate integrated municipal solid waste management strategies in the United States. The waste management unit processes included in this tool are waste collection, transfer stations, recovery, compost, combustion, and landfill. Additional unit processes included are electrical energy production, transportation, and remanufacturing. The process models include methodologies for environmental and cost analysis. The environmental methodology calculates life cycle inventory type data for the different unit processes. The cost methodology calculates annualized construction and equipment capital costs and operating costs per ton processed at the facility. The resulting environmental and cost parameters are allocated to individual components of the waste stream by process specific allocation methodologies. All of this information is implemented into the decision support tool to provide a life-cycle management evaluation of integrated municipal solid waste management strategies.     

Compartments for the Management of Municipal Solid Waste

Despite technological developments and improved liner-material applications, heavy metals in landfill leachate still penetrate the soil profile, polluting the soil and ground-water. An alternative approach therefore must be explored to reduce heavy-metal migration in soil-bentonite landfill liners. By considering the interaction of different heavy metals and their synergetic and antagonistics behaviors, such an approach could be developed. Low mobility metals such as Cu²⁺, and Pb²⁺ inhibit the adsorption of Cd²⁺ which is a moderate-mobility metal and Cu²⁺ sorption is decreased by the presence of Zn²⁺ and Cd²⁺. Therefore, Zn²⁺, a low-mobility metal, cannot be grouped with Cu²⁺. This way, four compatible metal groups have been identified: (1) low mobility: Pb²⁺, Cu²⁺, and Ag, (2) low mobility: Zn²⁺ and Cr³⁺; (3) moderate mobility: As²⁺, Fe²⁺, and Ni²⁺; (4) high mobility: Cd²⁺ and Hg²⁺. Cd²⁺ with a moderate mobility pattern is synergetic to Fe²⁺ and is more mobile with Ni²⁺. Therefore, Cd²⁺ is separated from the moderate-mobility group and is consigned with Hg, a high-mobility metal. The liner materials suitable for Hg²⁺ are assumed to be suitable for Cd²⁺ as well. Based on this concept, and to reduce heavy metal mobility, wastes should be segregated on compatibility basis according to their heavy metal contents before being disposed in different individual compartments. For wastes containing several incompatible heavy metals, sorting should be based on the heavy-metal with the highest concentration. Another solution is the manufacturing of products using compatible heavy metal combinations and then labeling them accordingly. Such waste segregation and landfill compartmentalization lowers risks of groundwater contamination and liner cost.     

Leachate from a Waste Disposal Centre reduces the initiation of arbuscular mycorrhiza,and spread of hyphae in soil

Irrigating arbuscular mycorrhizal plants with leachate from a waste disposal centre was examined in a set of experiments. Application of leachate at half the average concentration found in the field or higher reduced the growth of the host plant, the initiation of mycorrhizal colonisation, and hyphal growth of the mycorrhizal fungus Glomus pellucidum through the soil. Causes of these reductions are complex and interrelated, and associated with the electrical conductivity of the solution, toxicity of specific ions, in particular NH₄ ⁺, NH₃ and HCO₃ ⁻, and changes in the pH causing shifts in the equilibria of the soil solution. This revised version was published online in June 2006 with corrections to the Cover Date.     

Development of Methods for Detecting Viruses in Solid Waste Landfill Leachates

Methods were developed for detecting and concentrating enteric viruses in municipal solid waste landfill leachates. Poliovirus added to a leachate was not readily detectable, possibly because the virus was adsorbed to the leachate particulates. The masking effects associated with suspended solids in the leachate were overcome by adding a final 0.1 M sodium (tetra)ethylenediaminetetraacetate concentration to the leachate. A sodium (tetra)ethylenediaminetetraacetate-treated leachate could be clarified by filtration at pH 8.0 without a loss of virus. The clarified and sodium (tetra)ethylenediaminetetraacetate-treated leachate contained interfering materials of an anionic nature which prevented virus adsorption to epoxy-fiber glass filters. This interfering effect was overcome by treating the leachate with an anion-exchange resin. Viruses in the resin-treated leachate were concentrated by adjusting the leachate to pH 3.5, adding AlCl(3) to a final 0.005 M concentration, adsorbing the viruses to an epoxy-fiber glass virus adsorbent, and eluting the adsorbed viruses in a small volume. When this method was used to concentrate poliovirus 100-fold in a variety of leachates, the average virus recovery efficiency was 37%. With the methods described in this study, it should be possible to efficiently monitor solid waste disposal site leachates for enteric viruses.     

Interdependencies between Biotic and Abiotic Ferrous Iron Oxidation and Influence of pH,Oxygen and Ferric Iron Deposits

The effect of pH, oxygen and ferrous iron on growth and oxidation rates of iron-oxidizing bacteria (Gallionella spp and Leptothrix spp) as well as indirect effects, the most prominent being catalytic activity of the produced ferric iron deposits, were investigated. Deposits of biotic origin exhibit slightly lower surface oxidation rates compared to abiotically produced ferric iron. It was shown that the required habitat conditions of the studied species hardly overlap, but increase the pH/oxygen range of potential Fe(II) oxidation conditions. The study highlights the combined effect of microbial iron oxidation and catalytic properties of the Mn and Fe oxidation products.     

A Procedure for Life-Cycle-Based Solid Waste Management with Consideration of Uncertainty

The development of integrated solid-waste management (SWM) strategies that are efficient with respect to both cost and environmental performance is a complex task. It must incorporate the numerous interrelations among different unit operations in the solid waste system (e.g., collection, recycling, and combustion), and the large number of design parameters that affect estimates of cost and environmental emissions. Uncertainty in design and operational parameters can lead to uncertainty in the estimates of cost and emissions. This article describes an extension of the capability of the Integrated Solid Waste Management Decision Support Tool (ISWM DST) to enable consideration of the effects of uncertainty in input parameters. The uncertainty analysis capability is illustrated using a hypothetical case study of a typical municipality. Results show that increased expenditure does not necessarily result in a reduction in the expected levels of environmental emissions and that some SWM alternatives may be more robust, although deterministic estimates of their expected performances are similar. The uncertainty analysis also facilitates use of the ISWM DST by policy makers responsible for evaluation of the expected effect of SWM practices on, for example, greenhouse-gas emissions.     

Free Radical Generation at the Solid/Liquid Interface in Iron Containing Minerals

The potential for free radical release has been measured by means of the spin trapping technique on three kinds of iron containing particulate: two asbestos fibers (chrysotile and crocidolite); an iron-exchanged zeolite and two iron oxides (magnetite and haematite). DMPO (5,5'-dimethyl-1 -pirroline-N-oxide), used as spin trap in aqueous suspensions of the solids, reveals the presence of the hydroxyl and carboxylate radicals giving rise respectively to the two adducts [DMPO-OH] and [DMPO-CO2], each characterized by a well-defined EPR spectrum. Two target molecules have been considered: the formate ion to evidence potential for hydrogen abstraction in any biological compartment and hydrogen peroxide, always present in the phagosome during phagocytosis. The kinetics of decomposition of hydrogen peroxide has also been measured on all solids. Ferrozine and desferrioxamine, specific chelators of Fe(II) and Fe(III) respectively, have been used to remove selectively iron ions. Iron is implicated in free radical release but the amount of iron at the surface is unrelated to the amount of radicals formed. Only few surface ions in a particular redox and coordination state are active. Three different kinds of sites have been evidenced: one acting as H abstractor, the other as a heterogeneous catalyst for hydroxyl radical release, the third one related to catalysis of hydrogen peroxide disproportionation. In both mechanisms of free radical release, the Fe-exchanged zeolite mimics the behaviour of asbestos whereas the two oxides are mostly inert. Conversely magnetite turns out to be an excellent catalyst for hydrogen peroxide disproportionation while haematite is inactive also in this reaction. The results agree with the implication of a radicalic mechanism in the in vitro DNA damage and in the in vivo toxicity of asbestos.     

Dry-thermophilic anaerobic digestion of simulated organic fraction of Municipal Solid Waste: Process modeling

Solid retention time (SRT) is a very important operational variable in continuous and semicontinuous waste treatment processes since the organic matter removal efficiency - expressed in terms of percentage of Dissolved Organic Carbon (% DOC) or Volatile Solids (% VS) removed - and the biogas or methane production are closely related with the SRT imposed. Optimum SRT is depending on the waste characteristics and the microorganisms involved in the process and, hence, it should be determined specifically in each case.In this work a series of experiments were carried out to determine the effect of SRT, from 40 to 8 days, on the performance of the dry (30% Total Solids) thermophilic (55 °C) anaerobic digestion of organic fraction of Municipal Solid Wastes (OFMSW) operating at semicontinuous regime of feeding.The experimental results show than 15 days is the optimum SRT (the best between all proved) for this process. Besides, data of organic matter concentration and methane production versus SRT have been used to obtain the kinetic parameters of the kinetic model of Romero García (1991): the maximum specific growth rate of the microorganisms (μ_max = 0.580 days⁻¹) and the fraction of substrate non-biodegradable (α = 0.268).     

Retention of Metals Leached From Municipal Solid Waste Incineration (MSWI) Bottom Ashes in Soils

Utilization of bottom ash in road construction may lead to a release of contaminants that can affect the soil of the swales constructed along these roads. Column tests were performed to evaluate the retention behavior of Cu, Cr, Zn, and Pb, originating from municipal solid waste incineration (MSWI) bottom ash leachate, in two substrates: peat and mould (a cultural soil). A chemical sequential extraction method was used to predict the risk associated with the release of the retained elements with modifications of environmental conditions. Apart from the dissolution of organic matter (OM), ash leachate properties hindered the metal transport from peat. Mould was efficient only in removing Zn, making it a less favorable substrate for the leachate control along the roads. Readily soluble forms made up a minor fraction of the retained metals in peat, reducing the risk of metal release due to ion exchange and pH drop. Changes in redox potential might be the main cause of Zn desorption from peat as the Fe-Mn oxides were the main scavengers for this metal. Oxidation of OM would be the primary reason of Cu and Cr release, while for Pb both fractions (Fe-Mn oxides and OM) might equally contribute to the metal discharge.     

南海冷泉区深海沉积物中细菌的分离培养及多样性分析

为了认识南海深海冷泉区沉积物中可培养微生物的多样性,本文以冷泉区与非冷泉区两个站点的深海沉积物为样品,通过两种培养基(R2A海水培养基和2216E培养基)直接涂布或富集后平板分离纯化,从9个样品中共得到395株菌株,并通过16SrRNA基因鉴定,分属10个属。发现产芽胞细菌分布最广、丰度最大,包括3个属、15个种。其中芽胞杆菌(Bacillus)无论是在数量还是在种类上都分布最多。并且,随着水深和沉积物深度的增加,分离到的可培养微生物丰富度降低。本研究表明,即使在冷泉区,南海深海沉积物中产芽胞细菌也比较丰富。     

Effect of Temperature Variations on Vermicomposting of Household Solid Waste and Fecundity of Eisenia fetida

Experiments were conducted in winter (October to January) and summer (May to August) seasons to study the effect of seasonal temperature variations on the vermicomposting of household waste using Eisenia fetida earthworms. The prevailing temperatures during experiments were in the range of ?2.7°C to 35.0°C during winter season and 18.0°C to 44.4°C during summer season. Organic matter degradation was higher during winter than summer season. The electrical conductivity (EC) of vermicomposts was increased in the range of 2.3–7.8% in winter season; however, the increase in EC was 0.9–1.8% during summer season for different waste mixtures. There was about 56.2–80% increase in total Kjeldahl nitrogen (TKN) content during winter season, whereas the TKN increase was 23.9–44% during summers. The C:N ratio also decreased remarkably in all the waste mixtures during vermicomposting in both the seasons. However, the C:N ratio reduction was more significant during winter (47–60%) than in summer (31–44%). After the observation period, the net worm biomass achieved was higher during winter than summer season. The temperature variations during winter supported the life activities of earthworms more favourably than in summer. The results indicated that growth and reproductive potential of the earthworms were affected not only by the quality and quantity of the feed but also by ambient temperature.     

Generation of Domestic Solid Waste in Rural Areas: Case Study of Remote Communities in the Brazilian Amazon

The Brazilian rural population is estimated to be around 30 million people and many rural areas do not have universal access to basic infrastructure services, including those related to solid waste. There are very few scientific studies on rural domestic solid waste and more investigative work is needed to provide information for appropriate solid waste management policies. This paper aims to characterize rural domestic solid waste in terms of quantity and quality. Amazonian rural communities were chosen for our case study. The issue of domestic solid waste was characterized both by means of interviews, at household level, and by a study of industrialized products traded in the communities located along the banks of the Juruá River, in the Brazilian Amazon. Quantitative results have shown that generation of solid waste in these rural communities reaches 0.5 kg/person/day. Organic matter represents 90 % of domestic solid waste generation and is mainly reused to feed animals and/or is composted using a method called paú. Inorganic solid waste (10 %) is either reused, burned or inadequately dumped in open sites. Based on these data, the annual production of solid waste is 437 tons per year in these communities. Since infrastructure services are virtually non-existent in this rural context, even this amount of solid waste may have a serious environmental impact, with negative effects on the population’s health, particularly in terms of hazardous waste. Even though solid waste management solutions for rural populations might not always be based on economic efficiency, decision makers responsible for development and planning should present solutions that are socially, technologically, environmentally and economically suitable for this context.     

Anaerobic Immobilized Yeast Cell Fermentation and Anaerobic Remediation in Hybrid Reactor for Mineralization of Dicarboxylic Acid Solid Waste

Summary The solid resinous product (SRP) containing unsaturated/saturated dicarboxylic acid residues, phthalic acid and maleic acid is discharged as a solid waste during cracking of benzene over vanadium at temperatures above 500°C in the dicarboxylic acid manufacturing industry. In the present study the solid waste was diluted with water to a concentration of 0.5% w/v for microbial degradation. The waste was fermented in a reactor containing mesoporous activated carbon on which was immobilized Saccharomyces cerevisiae at an optimum residence time of 24 h at pH 6.5. The immobilized-yeast-treated samples were further treated in an upflow anaerobic reactor at an hydraulic retention time (HRT) of 0.1038 days at a hydraulic flow rate of 7.34 × 10⁻³ m³/day and chemical oxygen demand (COD) loading rate of 2.19 kg/m³/day. The pathway followed in the degradation of dicarboxylic acid into end products by anaerobic metabolism in the yeast cell fermentor and in the upflow anaerobic reactor was confirmed through HPLC, Fourier transform infra red spectroscopy and proton and ¹³C NMR spectroscopy.     

Investigation of Microorganisms in Bentonite Deposits

Microbiological characteristics of bentonite deposits were investigated as a natural analogue of microbial behavior in the buffer material for geological disposal of radioactive waste. Distributions of microorganisms in bentonite were examined at four sites in two different bentonite deposits in Japan. The sites included pond bottom, wetland, and wet mine gallery environments where bentonite layers have been left undisturbed for 2 to 30 years. Excavation was performed without using drilling water and the center parts of the cores were used for microbial examination. Plate counts with R2A medium of aerobic and anaerobic bacteria at the drilling mouth ranged from 10⁵ to 10⁷/g DW (dry weight) and from 10³ to 10⁶/g DW, respectively. The CFDA-AM (Carboxyfluorescein diacetate acetoxymethyl ester) cell counts ranged from 10⁶ to 10⁹/g DW. Bacterial numbers in the bentonite layers declined with distance from the drilling mouth; both aerobes and anaerobes were less than 10²/g DW and CFDA-AM cell counts less than 10⁶/g DW for core samples taken from approximately 1 m depth, except at the pond bottom. These results suggest that microbial activity in natural bentonite is lower than in typical soils and aquatic sediments and does not spread easily.     

Speciation and Environmental Fate of Chromium in Rivers Contaminated with Tannery Effluents

Redox and size speciation of chromium in rivers contaminated with tannery wastewater was carried out to provide insight into its transport and removal mechanisms. Total chromium was determined with Inductively Coupled Plasma‐Mass Spectrometry and Cr (VI) with Catalytic Adsorption Stripping Voltammetry. For the size speciation, particles were retained with a cartridge filter (cut‐off 1.2 μm) and the total filterable fraction was further fractionated with Tangential Flow Filtration to determine the concentrations of chromium associated with the High Molecular Weight Colloidal (HMWC), Low Molecular Weight Colloidal (LMWC) and Truly Dissolved (TD) fractions. Two fluvial systems of similar sizes, but located in contrasting climatic zones, were selected for comparison: the Sebou‐Fez system in Morocco and Dunajec River‐Czorsztyn Reservoir system in Poland. Particulate Cr dominated in the Sebou‐Fez system (about 90 %); while in the Dunajec‐Czorsztyn system, it represented only 17–53 % of the total chromium in raw water. Still, the partition coefficients [K_d] were of the same magnitude. Chromium (III) was the only form detected in Sebou‐Fez, whereas in Dunajec‐Czorsztyn Cr (VI) was also present with its proportion increasing downstream from the input of tannery wastewater due to the preferential removal of Cr (III). In the filtered water in Morocco a large fraction of Cr occurred in the HMWC fraction (50–70 %) at the two most contaminated sites, while the LMWC and TD forms prevailed at the non‐contaminated sites in the Sebou River. At a very high concentration, in the water in the proximity of tanneries (well above the theoretical saturation level) Cr precipitated as polynuclear Cr‐hydroxide. In Dunajec‐Czorsztyn, the partition of Cr (III) was approximately equal between the HMWC, LMWC and TD fractions, in contrast to Cr (VI) which occurred almost exclusively in the TD fraction. In both systems, Cr (III) was rapidly removed from the water to the sediments. The confluence of the Sebou with the Fez and the Czorsztyn reservoir trapped efficiently Cr (III) preventing its spreading over long distances. Cr (VI) showed conservative behavior and bypassed the Czorsztyn Reservoir. This study provides a first set of data on the partitioning of Cr (III) and Cr (VI) between the particulate, the colloidal and truly dissolved fractions in fluvial systems contaminated with tannery effluents. It also suggests that, in these systems, truly dissolved Cr (III) can be adequately modeled from the total filterable concentrations.