Geochemistry of leachates from selected coal mining and combustion wastes (Contribution / Kansas Water Resources Research Institute)

Sanitary landfills are the most widely utilized method of solid waste disposal around the world. With increased use and public awareness of this method of disposal, there is much concern with respect to the pollution potential of the landfill leachate.

Depending on the composition and extent of decomposition of the refuse and hydrological factors, the leachate may become highly contaminated. As leachate migrates away from a landfill, it may cause serious pollution to the groundwater aquifer as well as adjacent surface waters.

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There is growing concern about surface and groundwater pollution from leachate. Better understanding and prediction of leachate generation, containment, and treatment are needed. This book contains a literature review of various methodologies that have been developed for prediction, generation, characterization, containment, control, and treatment of leachate from sanitary landfills. The contents of this book are divided into nine chapters.

Each chapter contains theory and definition of the important design parameters, literature review, example calculations, and references.

Chapter 1 is devoted to basic facts of solid waste problems current status and future trends towards waste reduction and recycling.

Chapter 2 provides a general overview of municipal solid waste generation, collection, transport, resource recovery and reuse, and disposal options. The current status of sanitary landfill design and operation, problems associated with the landfilling, and future trends are presented in

Chapter 3. Methods of enhanced stabilization, recycling landfill space, methane recovery, and above grade landfilling, and closure and post closure care of completed landfills are also discussed in detail.

Chapter 4 provides a general overview of Subtitle D regulations and its impact upon sanitary landfilling practices.

Chapter 5 is devoted entirely to moisture routing and leachate generation mechanisms. Examples of calculation procedure for determining the leachate quantity produced at a landfill are presented.

Chapter 6 is devoted to chemical characterization of leachate that changes over the life of the fill. Both theoretical and experimental results are provided to estimate the leachate quality.

Chapter 7 provides leachate attenuation processes and mechanisms.

Chapter 8 is devoted to leachate collection systems. Natural soil sealants, admixed materials and synthetic membranes, their effectiveness, and methods of installation and economics are fully discussed.

Chapter 9 provides a detailed review of leachate treatment methodology.

Kinetic coefficients and treatment plant design considerations are summarized for the sole purpose of assisting consultants to design leachate treatment facilities. Leachate treatment case histories and numerous process trains are presented for treating leachate from young landfill. The book also describes how the process train can be changed effectively as leachate quality changes with time.

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Ground-water hydrology and the effects of vertical leakage and leachate migration on ground-water quality near the Shelby County landfill, Memphis, Tennessee (Water-resources investigations report)

Disposing of solids waste to landfill is regarded as one of the most economical means of handling waste though landfills pose pollution threat to both ground and surface water resources. However, landfill liners and good landfill management practices may reduce the impact of water contamination by landfills.

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Chemical analysis of groundwater beneath and near two landfills from New Zealand and Lesotho (in Southern Africa) showed that there are higher concentrations of chemicals such as Chlorides, TDS and COD than average. The water was also found to contain higher amounts of heavy metals.

High concentrations of chemical constituents, such as those found in leachate contaminated water may cause various health complications in humans if consumed.

To minimize possible hazards due to landfill leachate, future landfills must be lined at the base and sides by a combination of clay, geosynthetic clay and high-density polyethylene liners.

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Landfill Leachate is One of the Main Landfill Hazards

Landfill Leachate and landfill gas are the main landfill hazards which waste disposal to land imposes the environment. We will discuss both in this article. Landfill leachate is the name given to water that has passed through solid waste and contains organic and mineral contaminants. Therefore this effluent must be treated before discharge to the environment. Landfill leachate is a major concern for landfill sites located in close proximity to agricultural land, waterways and the public domain. The leachate and runoff from the site is directed to, and stored in, on-site leachate ponds. Landfill leachate is a notoriously complex substance to deal with, primarily because of its ever-changing composition. In recent years, biological treatment in Sequencing Batch Reactors (SBRs), and engineered wetland systems have proven that they can play a valuable role in leachate treatment.

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Landfill leachate is harmful for the environment if it escapes from landfills, and can even be highly toxic due to its high strength of contamination.

Generally, PAC addition after biological treatment and settlement can be used for leachate treatment, and can sometimes have a pronounced effect on organic carbon removal (BOD and COD). PAC alone is not adequate as the ammoniacal nitrogen in leachate is not removed by PAC addition.

In hot arid climates, the removal of just the organic content from a highly polluted drainage (such as landfill leachate) may not be sufficient for treatment where discharge is made to land or into a watercourse. This is because of the high concentrations of salts and other inorganic pollutants from the leachate into the natural water cycle, even at low concentrations, may lead to bio-accumulation. That is there may not be enough winter rainfall to flush the summer salt build-up away before the next spring. Such a situation would amount to a growing potential of environmental pollution in the resultant ecosystems which receive the discharge of treated leachate.

In many wetter areas however, biological leachate treatment will be perfectly adequate, and is a much lower cost option and generally uses far less energy than the more sophisticated systems used where saline build-up is a concern.

However, extracting leachate from landfills will be essential to control leachate levels and many have experienced difficulties in doing that. The fact is that landfill leachate is pretty tough to pump.". Electric centrifugal pumps continue to manage the liquids at many landfills, and do very well to keep the methane production at peak volume to realize the site's projected energy goals.

However, they do present certain concerns with regard to their design ATEX compliance and the possibility of landfill gas explosions
, and therefore most large landfill operators have moved to pneumatic leachate extraction pumping systems. These can also be very readily fitted within retro-drilled borehole wells, as combined leachate extraction and gas extraction wells.

The main landfill design standards are discussed at length and detail see also the top landfill leachate web site.

Waste Degradation and the Idea of Acceptable Release Rate

Every landfill is an engineering project with an engineered leachate management system. Any landfill liner is part of the system. The system should be designed to accommodate a range of seepage rates from very low (the best containment that can be achieved) to high (a controlled form of dilute and attenuate) depending on the degree of environmental protection needed at that site.

Many guidance documents or statutory assessment methods use absolute terms such as "total containment", "prevention of leachate and landfill gas migration", or "impermeable". These terms can lead to the erroneous belief that such concepts are achievable, and that failure to do so is indicative of poor materials or workmanship.

Landfill Problems - A Landfill Site Anatomy - kewego
http://landfill-site.com/html/landfills__environmental_probl.php Landfill problems. Landfill lining requirements, capping and landfill restoration described. Protect the environment and groundwater.

Keywords: landfill landfills trash problems groundwater pollution waste management

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Consideration of material properties demonstrates that, as all materials have a finite permeability, some finite seepage is inevitable.

For example, the frequently quoted requirements for one metre of clay with a maximum permeability of 10-9 m/s and a maximum leachate head of 1 metre implies, using Darcy's Law, a seepage rate of 1.7 m^/d/ha, and yet it is commonly referred to as the provision of "total containment".

Actual flow rates are affected by a range of ameliorating and aggregating factors. Calculation of actual seepage rates is complex, and should be carried out using risk assessment methodology carried out to a recognized methodology.

For gases, viscosity and diffusion characteristics must be taken into account. In general, mineral liners on their own are not usually effective barriers against gas migration, though they can be useful components of a multi-barrier system.

Measurements of hydraulic conductivity are of little relevance in respect to gas, as gas is able to pass through a barrier at a rate several orders of magnitude greater than that which may be measured for water.

All materials will allow the passage of liquids to an extent determined by their permeability. Risk assessment methodology will quantify the probability distribution for a derived seepage rate for a given liner/landfill situation.

This should be used either to assess the probable impact on the receiving source, or to determine the performance specification for the liner and landfill operational methods. In this way, an appropriate liner specification can be derived, incorporating a suitable safety margin.

Excessive over-engineering should be avoided, as this can itself may be considered to contravene the principles of sustainable development.

The statement we have made regarding the fact that flow through landfill containment systems will never be absolutely zero and will be a quantifiable small amount, cannot be refuted. It is a rigorously scientific approach to adopt this principle.

However, the concept of the fact that a seepage through a liner is acceptable has been resisted by some, and in particular can appear to be in conflict with the EC Groundwater Directive.

However, in certain circumstances, the discharge into the unsaturated zone of leachates containing List II substances (as defined by the EC Groundwater Directive) is permissible, provided that prior investigation has shown that this will be satisfactory and not significantly impact upon the environment.

Around the globe the primary concern will be to ensure the protection of groundwater, so for example in the EU landfill acceptability is classified by type within zones of travel time to a water source, and within resource protection areas.

Landfills are accepted as suitable for development when subject to adequate risk assessed engineered containment and operational safeguards.

Author Steve Evans has been writing about landfill daily cover and many other aspects of practical waste and secondary resource management since 2006. As you have been reading this article, there is a fair chance that you may enjoy his blog. We recommend a visit now!

Why Buy Organic - Sustainable Products?

Did you know that roughly 57 percent of all trash winds up in the over 7500 US landfills yearly according to the US EPA? Do you realize that trash production has nearly tripled since 1960? We certainly do live in a society that has adopted a disposable mentality! How many times have you heard somebody say, "Just go buy a new one?" When what they have could be repaired or reconditioned.

The danger to everyone on planet earth with this disposable mentality of ours is that all of our landfills emit harmful leachate gases that can become comingled with our water supply. Many older landfills do not have liners, leachate collection systems or groundwater monitoring systems. These dangerous gases are created when weather, humidity and non organic materials (plastics, phytochemicals) are compressed and aged together. (www.ejnet.org/rachel/rhwn231.htm) Also landfill land is not easily reclaimable for other uses due to the overcontamination of pollutants. If we keep needing to create more landfills for our trash, then soon we will be struggling for good natural land to build on or use for open spaces.

How can you help to change this dangerous and concerning consumer course? You can purchase organic, sustainable and renewable consumer goods. Goods made from organic or sustainable materials are easily recyclable or composted and does not go "toxic" when breaking down. A good example is 100% organic cotton clothing. It makes good logic that since the clothing is made from only naturally occurring plants that the cloth will easily return to the earth in a positive manner. Each stage of this product's life cycle is sustainable and minimizes negative impact on the earth and environment.

What assurance do you have that a product is "green", "organic" or "earth friendly"? Luckily there are standards in place and certain labeling that you can look for. Here is website that explains each type of labeling now available http://mts.sustainableproducts.com/standards.htm . Remember, each time you buy something you vote with your purchase! If we all choose to buy more sustainable products we can reduce pollution, the landfill problem and create a healthier, more productive living environment!

Khrom Chen Virtual Mall is a unique online shopping center that carries a variety of green, organic, sustainable, earth friendly and eco friendly products. We also carry a variety of products that support a healthy lifestyle, and personal enrichment products.

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What is Leachate? The Secret Story of Leachate

Leachate can be any water that once it has drained through a medium takes up chemicals and solid materials during its passage. The term leachate is most often used in connection with landfills. Landfill leachate is contaminated 'dirty' water that is produced when rainwater comes into contact with waste materials on the area of the landfill. It contains a large number of different contaminants, probably the most significant of which is ammonia.

The second most common type of leachate encountered is the black odorous run-off from manure heaps and from some composting facilities.

If leachate is allowed to leak from a landfill it will usually cause pollution both locally around the waste, and it may form a plume of contamination within groundwaters it enters and a plume of groundwater pollution may move away from the landfill over time to contaminate wells and any drinking water taken from them.

Leachate forms from both the combination of liquids that are dumped in a tip or landfill, and liquids that form through decomposition of wastes, as precipitation filters through the wastes. It is a liquid which is mostly organically contaminated but which will also contain low levels of most of the liquids disposed of in the landfill from which it emanates.

Sometimes leachate can be produced by a landfill, which is sealed by a low permeability capping layer. That is normally the result of a rise in pressure on the landfill when additional loads are placed on the landfill forcing compression of the structure or the presence of excess water.

Leachate is produced by the percolation of precipitation through a landfill (from rainfall and snowmelt) once it penetrates the landfill's daily, intermediate, or final cover. However, the quantity that penetrates a well vegetated cover is lower than many expect, due to the evaporation from the surface, which will include the transpiration from the leaves of he foliage on he surface.

As the water passes vertically downward through the waste mass, it comes into contact with the waste, picking up chemical contaminants and biological impurities as it goes, and the deeper the waste he stronger it gets. It also gets stronger if it stands from a long while in the waste which is not highly surprising.

There are two main types of leachate produced in landfills which contain biological municipal solid waste (MSW). These are known as acetogenic leachate and methanogenic leachate. The methanogenic type is often black in color always smelly and may smell of bad eggs. Methanogenic only has only a slight smell and is brown or golden colored.

Acetogenic leachate is the young leachate which is produced in a landfill first. It has a very high Chemical Oxygen Demand (COD) which can be as high as hundreds of thousands of milligrams per litre for short periods, soon after the cells of he organic waste break open or "lyse" and the complex compounds which make up live cell tissue drain out of the cells.

The demand for oxygen in a modern quite rapidly filled landfill, is so intense that within a few months of deposition a new cell of waste will lack oxygen within the airspaces. Oxygen will be present in the waste which is then said to be in an anoxic condition.

Over time the original oxygen in the waste and in the leachate becomes depleted as biological fermentation proceeds, and at some point ancient bacteria which have always been present in airless bogs and swamps and lie dormant in our environment multiply and take over the reaction within he waste.
These are known as methanogenic bacteria. Why are they called that? Well, it is simple really! They produce the gas known as methane!

All that brings me around to the point where I can now define methanogenic leachate. Yes. You have guessed it. Methanogenic leachate is the leachate that is produce by a methane producing anaerobic landfill. By the time it has become methanogenic however, the process of decomposition by fermentation has reduced the COD to quite possibly 1/100 th of its maximum value, or even 1/1000 th.

However, the leachate is hardly any less toxic to aquatic life, because the ammonia present in dissolved and gaseous forms remains high, and thus as we stated earlier is one of the most important contaminants in leachate.

That is the story of leachate from young (acetogenic) to old (methanogenic).

 

Visit Steve Last's web site for Part 2 of this article at The Leachate Web Site. he is an expert on leachate treatment and has been designing and building leachate treatment plants for more than 20 years.

What is Leachate? And Garbage Juice Explained

Leachate is the liquid produced when water percolates through any permeable material. Silage leachate is a form of leachate which is a serious environmental problem, however, when people refer to leachate they are usually talking about the contaminated water that is produced by water percolating through waste.

Leachate is produced when water filters downward through a landfill, and as it does so it picks up dissolved materials from the decomposing wastes. Depending on characteristics of the landfill and the wastes it contains, the leachate may vary from being relatively harmless or extremely toxic.

Landfills with low permeability daily cover, in wet and high rainfall climates with high slopes (less than 20 to 1) are particularly susceptible. Leachate seeps also are possible if operators use recirculation to return concentrates from, for example, RO systems and we have known seeps to be particularly persistent where systems are inadvertently placed over well-compacted, former haul roads.

Landfill leachate can also be defined as liquid that leaks from a landfill and enters the environment. This liquid may either exist in the landfill as deposited, or it may be created after rainwater mixes with the chemical waste in in a landfill.

Landfill leachate quality varies as a function of many factors including waste type, waste depth, time, weather, and landfill operations.

Designed to hold our garbage and to prevent it from contaminating our soil and our drinking water, the modern landfill has become a highly technical and complex structure. Contrary to what many might think, a landfill is not just a pile of garbage. Because these landfills are designed not to let the leachate escape and pollute the surrounding ground the landfills hold the leachate for a long while before it can descend through the waste and be removed from the bottom. This means that the modern landfill produces some of the strongest and most contaminated leachate waters ever produced anywhere.

Treatment of this polluted water is a complex task due to its nature. A typical leachate is highly contaminated with ammonia, organic contaminants, halogenated hydrocarbons and some heavy metals (although this can be overstated in leachate from modern well controlled landfills). Also, leachates commonly hold high concentrations of inorganic salts.

Treatment lagoons and leachate ponds are a method of leachate management, but they are usually ineffective fall all but the freshest and weakest landfill leachates.

In dry climates and arid areas, removal of the organic content from a highly polluted drainage (such as landfill leachate) is not sufficient. This is because of introducing the salts and other inorganic pollutants from the leachate into the natural water cycle, even at minimal concentrations, can lead to bio-accumulation (a growing potential of environmental pollution) in the resultant ecosystems which receive the discharge of treated leachate.

Additionally, although the biodegradability of leachate organic compounds declines with time, complex organic compounds, such as humic substances and manufactured chemical compounds, remain in solution.

Biological treatment is the most favourable procedure that should be used for leachate treatment, and biological treatment should also be used in those cases when chemical/physical treatment is also required. Biological leachate treatment is a relatively low cost process in which organics are degraded mainly to carbon dioxide, water, and biomass.

All those substances that are been eliminated using a pre-treatment of biological degradation no longer have to be treated by means of the much higher cost chemical/physical procedures available.

As the landfill age increases the treatment of the leachate it produces will mainly focus on the nitrification of ammonia. Biological denitrification can then be achieved subsequently when an external organic substrate is added to the leachate.

It is important to stress that the design criteria for sewage treatment plants cannot be used for this polluted water. For the design and operation of biological leachate treatment plants specific points have to be respected and a leachate treatment process expert is essential. For many adopting the advice of sewage treatment experts for leachate-treatment has resulted in inappropriate process designs, and wasted money, time and effort.

For leading world class expertise in leachate treatment visit the top leachate web site. These guys have built the biggest and most complex biological leachate
treatment plants in the world to treat the strongest and most difficult to treat leachates found anywhere.