2.0. Leachate
Leachate is the liquid that drains or 'leaches' from a landfill; it varies widely in composition regarding the age of the landfill and the type of waste that it contains (Henry and Heinke, 1996). It can usually contain both dissolved and suspended materials.
Leachate is any liquid that is passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed. Leachate is a widely used term in environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful substances which may then enter the environment. It is most commonly used in the context of land-filling of putrescible or industrial waste.
In the narrow environmental context; leachate is therefore any material that drains from land or stockpiled material and contain significantly elevated concentrations of undesirable material derived from the material that it has passed through.
2.2.1. Open Dump
An open dump is an illegal waste disposal site and should not be confused with permanent municipal solid waste landfill or recycling facility. If allowed to remain, open dumps often grow larger, and may attract dumping of solid and hazardous waste. Open dumps pose the following health, safety and environmental threats:
• Fire and explosion,
• Inhalation of toxic gases,
• Injury to children playing on or around the dump site,
• Disease carried by mosquitoes, flies, and rodents,
• Contamination of soil and ground water ,
• Damage to plant and wide life habitats,
• Contamination of drinking water ,
• Decreases in the quality of life to nearby residents and Local Community, etc.
Open dumps create a public nuisance, divert land for more productive uses and depress the value of surrounding land (Illinois EPA's house hold hazardous waste programme).
2.2.2. Open Dump Leachate
Open dump leachate can be defined as liquid that percolates from the dump and enters the environment. This liquid may either exist in the open dump as deposit or it may be created after rain water mixes with chemical waste in the dump. Factors affecting open dump leachate quality include; waste type, waste depth, time, age of dump, weather, rainfall, etc.
2.2.3. Landfill Leachate
A landfill is an area of land where large amounts of waste materials are buried under the earth. Leachate from a landfill varies widely in composition depending on the age of the landfill and the type of waste that it contains. (Henry et al, 1996 Young; 1992). It can usually contain both dissolved and suspended materials.
According to Francis and Dodge, 1970, landfill leachate have been known to contain a wide range of heavy metals, decomposition of the solid waste disposed in a landfill determines the amount of heavy metals in the leachate (Thayer, 1989), and decomposition varies with the source of waste generation, (Campbell, 1976, Alter, 1989) and with the compositing process of landfill, it acidic groundwater quality and around the landfill is mainly affected due to infiltration or disposal of leachates while surface water quality may be affected if untreated.
Landfill leachates run-off into nearby water body (Christensen, 1992), like ground water which is the source of well , springs etc and could percolate through soils.
2.2.4. Composition of Leachate
When water percolates through the waste, it promotes and assist process of decomposition by bacteria and fungi. These processes in turn release by-products of decomposition and rapidly use up any available oxygen creating an anoxic (no oxygen) environment. In actively decomposing waste the temperature rises and the pH falls rapidly and many metal ions which are relatively insoluble at natural pH can become dissolved in the developing leachate. The decomposing processes themselves release further water which adds to the volume of leachate. Leachate also reacts with materials that are not themselves prone to decomposition such as fire ash and cement based building materials changing the chemical composition. In sites with large volume of building waste, especially those containing gypsum plaster, the reaction of leachate with the gypsum can generate large volumes of hydrogen sulphide (H2S) which may be released in the leachate and may also form a large component of the landfill gas (Kjeldsen, et al, 1996).
In a landfill that receives a mixture of municipal, commercial and mixed industrial waste but exclude significant amounts of concentrated specific chemical waste, landfill leachate may be characterized as a water-based solution of four groups of contaminants; dissolved organic matter (alcohols, acids, aldehydes, short chain sugars etc), inorganic macro components (common cations and anions including sulphate, chloride, iron, alluminium, zinc and ammonia), heavy metals (Pb, Ni, Cu, Hg) and xenobiotic organic compounds such halogenated organics (PCBs, dioxins etc) (Kjeldsen et al, 1996).
This composition of leachate is common to all types of leachate.
2.2.5. Other Types of Leachate
Leachate can also be produced from that was contaminated by chemicals or toxic materials used in industrial activities such as factories, mines or storage sites. Compositing sites in high rainfall also produce leachate.
Leachate is also associated with stockpiled coal and with waste materials from metal ore mining and other rock extraction processes, especially those in which sulphide containing materials are exposed to air and thus to oxygen generating acidic, sulphur-rich liquors often with elevated concentrations.
In the context of civil engineering (more specifically reinforced concrete design), leachate refers to the effluent of pavement wash-off (that may include melting snow and ice with salt) that permeates through the cement paste onto the surface of the steel reinforcement thereby catalyzing its oxidation and degradation. Leachate can be genotoxic in nature (singh, Chandra, Kumar G, Chauhan, Kumar, R. (2007).
2.2.6. Silage Leachate
According to Graves and vanderstappen, 1973, silage leachate can be generated by several types of farm storage facilities including plastic wrapped or bagged large round bales. Leachate production depends on the type of materials, its moisture and nitrogen content; how it is handled and the ambient condition of the storage environment of this moisture content is the most critical. Silage leachate is 95% water and 5% solids. The solid portion consists of soluble highly digestible nutrients.
Leachate formed from silage process has been the focus of many experiments involving ground water contamination. Research has also been done on plant which got burnt after leachate application.
In the land application recommendation section of silage leachate and water it is stated that "care must be taken to prevent plant die-off and burning of vegetation due to leachate application" (high concentration of it suspected).
When silage leachate is allowed to enter into land, it deplete soil oxygen. With its high oxygen demand, high reducing potential, and low pH, leachate interaction with soil and/or bedrock can cause minerals such as iron (Fe) and manganese (Mn) to become soluble and leach the ground water (NRCS, 1995).
In a study of leachate metabolites and their ability to be reabsorbed by plants, Turkey and Medenburg (1964) found that leached nutrients could be absorbed by both roots and foliage. They also discovered that under some circumstances, foliar absorption may have a greater impact on the plant than root absorption. Plant leachate may provide nutrients for plant up take, but they may also be harmful especially at very high/heavy concentrations.
Leachate is the liquid that drains or 'leaches' from a landfill; it varies widely in composition regarding the age of the landfill and the type of waste that it contains (Henry and Heinke, 1996). It can usually contain both dissolved and suspended materials.
Leachate is any liquid that is passing through matter, extracts solutes, suspended solids or any other component of the material through which it has passed. Leachate is a widely used term in environmental sciences where it has the specific meaning of a liquid that has dissolved or entrained environmentally harmful substances which may then enter the environment. It is most commonly used in the context of land-filling of putrescible or industrial waste.
In the narrow environmental context; leachate is therefore any material that drains from land or stockpiled material and contain significantly elevated concentrations of undesirable material derived from the material that it has passed through.
2.2.1. Open Dump
An open dump is an illegal waste disposal site and should not be confused with permanent municipal solid waste landfill or recycling facility. If allowed to remain, open dumps often grow larger, and may attract dumping of solid and hazardous waste. Open dumps pose the following health, safety and environmental threats:
• Fire and explosion,
• Inhalation of toxic gases,
• Injury to children playing on or around the dump site,
• Disease carried by mosquitoes, flies, and rodents,
• Contamination of soil and ground water ,
• Damage to plant and wide life habitats,
• Contamination of drinking water ,
• Decreases in the quality of life to nearby residents and Local Community, etc.
Open dumps create a public nuisance, divert land for more productive uses and depress the value of surrounding land (Illinois EPA's house hold hazardous waste programme).
2.2.2. Open Dump Leachate
Open dump leachate can be defined as liquid that percolates from the dump and enters the environment. This liquid may either exist in the open dump as deposit or it may be created after rain water mixes with chemical waste in the dump. Factors affecting open dump leachate quality include; waste type, waste depth, time, age of dump, weather, rainfall, etc.
2.2.3. Landfill Leachate
A landfill is an area of land where large amounts of waste materials are buried under the earth. Leachate from a landfill varies widely in composition depending on the age of the landfill and the type of waste that it contains. (Henry et al, 1996 Young; 1992). It can usually contain both dissolved and suspended materials.
According to Francis and Dodge, 1970, landfill leachate have been known to contain a wide range of heavy metals, decomposition of the solid waste disposed in a landfill determines the amount of heavy metals in the leachate (Thayer, 1989), and decomposition varies with the source of waste generation, (Campbell, 1976, Alter, 1989) and with the compositing process of landfill, it acidic groundwater quality and around the landfill is mainly affected due to infiltration or disposal of leachates while surface water quality may be affected if untreated.
Landfill leachates run-off into nearby water body (Christensen, 1992), like ground water which is the source of well , springs etc and could percolate through soils.
2.2.4. Composition of Leachate
When water percolates through the waste, it promotes and assist process of decomposition by bacteria and fungi. These processes in turn release by-products of decomposition and rapidly use up any available oxygen creating an anoxic (no oxygen) environment. In actively decomposing waste the temperature rises and the pH falls rapidly and many metal ions which are relatively insoluble at natural pH can become dissolved in the developing leachate. The decomposing processes themselves release further water which adds to the volume of leachate. Leachate also reacts with materials that are not themselves prone to decomposition such as fire ash and cement based building materials changing the chemical composition. In sites with large volume of building waste, especially those containing gypsum plaster, the reaction of leachate with the gypsum can generate large volumes of hydrogen sulphide (H2S) which may be released in the leachate and may also form a large component of the landfill gas (Kjeldsen, et al, 1996).
In a landfill that receives a mixture of municipal, commercial and mixed industrial waste but exclude significant amounts of concentrated specific chemical waste, landfill leachate may be characterized as a water-based solution of four groups of contaminants; dissolved organic matter (alcohols, acids, aldehydes, short chain sugars etc), inorganic macro components (common cations and anions including sulphate, chloride, iron, alluminium, zinc and ammonia), heavy metals (Pb, Ni, Cu, Hg) and xenobiotic organic compounds such halogenated organics (PCBs, dioxins etc) (Kjeldsen et al, 1996).
This composition of leachate is common to all types of leachate.
2.2.5. Other Types of Leachate
Leachate can also be produced from that was contaminated by chemicals or toxic materials used in industrial activities such as factories, mines or storage sites. Compositing sites in high rainfall also produce leachate.
Leachate is also associated with stockpiled coal and with waste materials from metal ore mining and other rock extraction processes, especially those in which sulphide containing materials are exposed to air and thus to oxygen generating acidic, sulphur-rich liquors often with elevated concentrations.
In the context of civil engineering (more specifically reinforced concrete design), leachate refers to the effluent of pavement wash-off (that may include melting snow and ice with salt) that permeates through the cement paste onto the surface of the steel reinforcement thereby catalyzing its oxidation and degradation. Leachate can be genotoxic in nature (singh, Chandra, Kumar G, Chauhan, Kumar, R. (2007).
2.2.6. Silage Leachate
According to Graves and vanderstappen, 1973, silage leachate can be generated by several types of farm storage facilities including plastic wrapped or bagged large round bales. Leachate production depends on the type of materials, its moisture and nitrogen content; how it is handled and the ambient condition of the storage environment of this moisture content is the most critical. Silage leachate is 95% water and 5% solids. The solid portion consists of soluble highly digestible nutrients.
Leachate formed from silage process has been the focus of many experiments involving ground water contamination. Research has also been done on plant which got burnt after leachate application.
In the land application recommendation section of silage leachate and water it is stated that "care must be taken to prevent plant die-off and burning of vegetation due to leachate application" (high concentration of it suspected).
When silage leachate is allowed to enter into land, it deplete soil oxygen. With its high oxygen demand, high reducing potential, and low pH, leachate interaction with soil and/or bedrock can cause minerals such as iron (Fe) and manganese (Mn) to become soluble and leach the ground water (NRCS, 1995).
In a study of leachate metabolites and their ability to be reabsorbed by plants, Turkey and Medenburg (1964) found that leached nutrients could be absorbed by both roots and foliage. They also discovered that under some circumstances, foliar absorption may have a greater impact on the plant than root absorption. Plant leachate may provide nutrients for plant up take, but they may also be harmful especially at very high/heavy concentrations.
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