Metal Contaminants in Leachate from Sanitary Landfills

The uncontrolled disposal of solid wastes poses an immediate threat to public health and a long term threat to the environmental well being of future generations. Solid waste is waste resulting from human activities that is solid and unwanted (Peavy et al., 1985). If unmanaged, dumped solid wastes generate liquid and gaseous emissions that are detrimental to the environment. This can lead to a serious form of contamination known as metal contamination, which poses a risk to human health and ecosystems. For example, some heavy metals (cadmium, chromium compounds, and nickel tetracarbonyl) are known to be highly toxic, and are aggressive at elevated concentrations. Iron, copper, and manganese can cause staining, and aluminium causes depositions and discolorations. In addition, calcium and magnesium cause hardness in water causing scale deposition and scum formation. Though not a metal but a metalloid, arsenic is poisonous at relatively high concentrations and when diluted at low concentrations causes skin cancer. Normally, metal contaminants are found in a dissolved form in the liquid percolating through landfills. Because average metal concentrations from full-scale landfills, test cells, and laboratory studies have tended to be generally low, metal contamination originating from landfills is not generally considered a major concern (Kjeldsen et al., 2002; Christensen et al., 1999). However, a number of factors make it necessary to take a closer look at metal contaminants from landfills. One of these factors relates to variability. Landfill leachate can have different qualities depending on the weather and operating conditions. Therefore, at one moment in time, metal contaminant concentrations may be quite low, but at a later time these concentrations could be quite high. Also, these conditions relate to the amount of leachate that is being generated. Another factor is biodiversity. It cannot be assumed that a particular metal contaminant is harmless to flora and fauna (including micro organisms) just because it is harmless to human health. This has significant implications for ecosystems and the environment. Finally, there is the moral factor. Because uncertainty surrounds the potential effects of metal contamination, it is appropriate to take precautions to prevent it from taking place. Consequently, it is necessary to have good scientific knowledge (empirically supported) to adequately understand the extent of the problem and improve the way waste is being disposed of

Centrifuge modelling and dynamic testing of municipal solid waste (MSW) landfills

An investigation into the seismic behaviour of municipal solid waste (MSW) landfills by dynamic centrifuge testing was undertaken. This paper presents physical modelling of MSW landfills for dynamic centrifuge testing, with regard to the following research areas: 1. amplification characteristics of municipal solid waste; 2. tension induced in geomembranes placed on landfill slopes due to earthquake loading; 3. damage to landfill liners due to liquefaction of foundation soil. A model waste, that has engineering properties similar to MSW, is presented. A model geomembrane that can be used in centrifuge tests is also presented. Results of dynamic centrifuge tests with the model geomembrane showed that an earthquake loading induces additional permanent tension (∼25%) in the geomembrane. © 2006 Taylor & Francis Group.

Centrifuge modelling and dynamic testing of municipal solid waste (MSW) landfills

An investigation into the seismic behaviour of municipal solidwaste (MSW) landfills by dynamic centrifuge testing was undertaken. This paper presents physical modelling of MSW landfills for dynamic centrifuge testing, with regard to the following research areas: 1. amplification characteristics of municipal solid waste; 2. tension induced in geomembranes placed on landfill slopes due to earthquake loading; 3. damage to landfill liners due to liquefaction of foundation soil. A model waste, that has engineering properties similar to MSW, is presented. A model geomembrane that can be used in centrifuge tests is also presented. Results of dynamic centrifuge tests with the model geomembrane showed that an earthquake loading induces additional permanent tension (∼25%) in the geomembrane. © 2006 Taylor & Francis Group, London.

Waste collection routing-limited multiple landfills and heterogeneous fleet

This article deals with a real-life waste collection routing problem. To efficiently plan waste collection, large municipalities may be partitioned into convenient sectors and only then can routing problems be solved in each sector. Three diverse situations are described, resulting in three different new models. In the first situation, there is a single point of waste disposal from where the vehicles depart and to where they return. The vehicle fleet comprises three types of collection vehicles. In the second, the garage does not match any of the points of disposal. The vehicle is unique and the points of disposal (landfills or transfer stations) may have limitations in terms of the number of visits per day. In the third situation, disposal points are multiple (they do not coincide with the garage), they are limited in the number of visits, and the fleet is composed of two types of vehicles. Computational results based not only on instances adapted from the literature but also on real cases are presented and analyzed. In particular, the results also show the effectiveness of combining sectorization and routing to solve waste collection problems.

Intertemporal and Spatial Depletion of Landfills

This paper generalizes Hotelling's (1931) theory of nonrenewable resources to situations where resource pools and their users are distributed spacially. Extraction and transport costs are assumed to be linear in the rate of extraction, but utilization of each deposit may require a setup cost.

Recycling potential of urban solid waste destined for sanitary landfills: the case of Indaiatuba, SP, Brazil

The urban solid waste of the city of Indaiatuba (pop. 175 000), located in the state of São Paulo, was characterized, focusing on the recycling potential. For this purpose, collected waste was subdivided into 27 items, classified by mass and volume. About 90% of this waste was found to be potentially recyclable and only 10% requiring landfilling. The compostable organic matter, in the form of food and garden waste, both with high moisture content (51 and 41%, respectively), represents 54% in mass and 21% in volume. The most common type of plastic in this waste is high density polyethylene, whose estimated disposal is about 5000 kg day(-1). A socio-economic analysis of the waste generation indicates that low-income neighbourhoods discard relatively less packaging and more food waste, shoes and construction debris than middle and high income ones, which may be due to low purchasing power and schooling. Our findings indicate that more aluminium and uncoloured polyethylene terephthalate is discarded in the warmest months of the year, probably due to a greater consumption of canned and bottled drinks.

Landfills as risk factors for respiratory disease in children

Objective: To investigate the relationship between exposure to a landfill site closed 6 years previously and respiratory symptoms in children aged up to 13 years.Method: This was a cross-sectional study conducted in Varzea Paulista, in the state of São Paulo, Brazil. One adult in every household in a neighborhood close to the landfill and from a randomized sample of households in another neighborhood with similar socioeconomic characteristics but no landfill were interviewed and asked about respiratory symptoms and other variables relating to children aged up to 13. A logistic regression model was used to study this relationship.Results: The likelihood of a child having respiratory symptoms was a function of -2.36 + 0.43 if the child was less than 2 years old; + 0.24 if the child lived in the landfill area; -0.67 if there was a computer at home; + 0.54 if firewood was burnt in the home in the last year; + 0.94 if the child was diagnosed with asthma; + 0.87 if the child visited a health service in the previous 30 days.Conclusion: The authors conclude that living near to a landfill closed 6 years previously may be a risk factor for respiratory disease in children.

Small-scale landfills: impacts on groundwater and soil

In Brazil, the large quantities of solid waste produced are out of step with public policies, technological developments, and government budgets for the division. In small municipalities, the common lack of technological knowledge and financial conditions for suitable waste disposal has resulted in a large number of illegal dumps. Therefore, small sanitary landfill facilities are working with simplified operations focusing on cost reduction and meeting the economic and technological standards of the city without endangering the environment or public health. Currently, this activity is regulated at a federal level although there is some uncertainty regarding the risk of soil and aquifer contamination as theses facilities do not employ liners. Thus, this work evaluates a small landfill to identify changes in soil and groundwater using geotechnical parameters, monitoring wells, and geophysical tests performed by electrical profiling. It is verified that based on current conditions, no contaminants have migrated via underground water aquifers, and overall no significant changes have occurred in the soil. It is concluded that, despite its simplicity, the method investigated is a viable alternative for the final disposal of municipal solid waste from small cities, especially in developing countries.

Small-scale landfills: impacts on groundwater and soil

In Brazil, the large quantities of solid waste produced are out of step with public policies, technological developments, and government budgets for the division. In small municipalities, the common lack of technological knowledge and financial conditions for suitable waste disposal has resulted in a large number of illegal dumps. Therefore, small sanitary landfill facilities are working with simplified operations focusing on cost reduction and meeting the economic and technological standards of the city without endangering the environment or public health. Currently, this activity is regulated at a federal level although there is some uncertainty regarding the risk of soil and aquifer contamination as theses facilities do not employ liners. Thus, this work evaluates a small landfill to identify changes in soil and groundwater using geotechnical parameters, monitoring wells, and geophysical tests performed by electrical profiling. It is verified that based on current conditions, no contaminants have migrated via underground water aquifers, and overall no significant changes have occurred in the soil. It is concluded that, despite its simplicity, the method investigated is a viable alternative for the final disposal of municipal solid waste from small cities, especially in developing countries.

A study of vegetation problems associated with refuse landfills /

Mode of access: Internet.

Recovery, processing, and utilization of gas from sanitary landfills /

Mode of access: Internet.

Design and construction of covers for solid waste landfills /

Mode of access: Internet.