Impact of landfill caps on leachate emissions: an Austrian case study - Recycling News (press release)

Brussels -- Municipal solid waste (MSW) landfills, which consist of everyday consumer items, are potential long-term sources of emissions that could threaten the environment and human health if they are not managed carefully after closure. New research has presented a methodology to estimate future emission levels for closed MSW landfills and the impact of different aftercare strategies.

Kommunalunternehmen des Landkreises Bad KissingenGlobally, landfilling is the main method for disposing of solid waste. Highly industrialised countries, such as the US, the UK and Finland, extensively depend on landfilling their waste without any pre-treatment. As MSW landfills are possibly long-term sources of emissions, these sites need to be managed beyond closure. According to the EU Landfill Directive, which took effect in 1999, landfill operators have to continue managing sites after closure as long as the authority considers the landfill not likely to present a hazard to the environment any more.
Cap removed after 20 years

The researchers used an Austrian MSW landfill in Breitenau as a case study to evaluate emission levels from the site and to demonstrate the long-term environmental effects of installing a final cover to prevent emissions. This site was closed in 1989 and was capped with layers of gravel (0.2 metres) and sandy silt (0.9 metres). The temporary cap was removed after 20 years (in 2009) and a composite lining system was installed as the final cover. The study focused on one landfill compartment, which contained around 35,000 tons of MSW.

Leachate emissions decrease very slowly and may have environmental impacts for centuries to come. The approach to evaluate potential future emissions was based on a comprehensive assessment of the state of the landfill and included analysis of monitoring data, investigations of landfilled waste, and an evaluation of containment systems and site-specific factors, such as climate. Future emission levels were modelled and site-specific predictions of leachate emissions were presented.

Increased leachate after flushing

The results suggest that leachate concentrations increased considerably at the site when there was a change in the water flow pattern of the waste during final cover construction. Specifically, the concentrations of leachate pollutants chloride and ammonia-nitrogen increased from 200 to 800 milligrams per litre (mg/l) and 140 to about 500 mg/l, respectively. It is found that a period of intensive flushing after the change of the water flow pattern and before the final cover installation would have reduced the amount of leachable substances within the landfill and substance concentrations in the leachate would decrease to 11 mg/l of chloride and 79 mg/l of ammonia-nitrogen within 50 years.

Different aftercare strategies

A decline in water infiltration due to the installation of an impermeable top cover may lead to high substance concentrations in the leachate for centuries (above 400 mg of chloride per litre and 200 mg ammonia-nitrogen per litre), but with low associated annual emission loads (below 12 kg of chloride and 9 kg of ammonia-nitrogen per year). However, a gradual decrease in the cover?s performance may be expected without cover maintenance and would be associated with higher emission loads of a maximum of 50 kg of chloride and 30 kg of ammonia?nitrogen.

The methodology can be applied to other closed landfill sites to illustrate the effect of different aftercare strategies on the landfill pollution hazard. The researchers caution that emission models should be treated as tools to demonstrate the effect of different landfill conditions and not as deterministic forecasts of the future.

Original source: David Laner, D., Fellner, J. & Brunner, P.H. (2011) Future landfill emissions and the effect of final cover installation ? A case study. Waste Management. 31 (7):1522-1531

Quelle: EU commission

View the original article here

Long-Term Leachate Emissions From Municipal Solid Waste Landfills Are Unknown

The Swiss have invariably been highly environmentally aware, and for a long time have looked after their environment in an exemplary fashion. The 'Guidelines to waste product control in Switzerland ' ( EKA, 1986 ) were set in 1986, well before many states. One mandatory objective of this as a code of sound practise has been that all waste product management procedures need to provide materials which either are reusable or can be dumped in a rubbish heap without any negative or damaging environmental impact for long-term periods. This type of landfilling would be called 'final storage ' and the wastes in the final storage must naturally by inference have 'final storage quality'. Emissions from a last storage quality dump must be a close fit with the quality in the natural environment without any extra treatment. Another imperative objective of the Swiss waste product control policy is that each generation handles its waste to a standing of last storage quality. So that the reactions in a dump to take it to last storage quality have to be quick enough to all be finished inside thirty years, and ideally less.

As an effect of this policy, has each borough's solid waste landfills been proved to be able to get to the last storage quality within about 30 years after disposal? The final storage concept focuses predominantly on the solid waste itself stabilizing so that the new generation won't have to depend instead on the synthesised or natural barriers round the rubbish heap body, and the answer's a powerful no! The dump body has to reach an 'inert ' state so that the emissions from the rubbish heap have compatibility with the environment for long-term periods regardless of the retardation and attenuation capacities of surrounding materials. But this inactive state depends on geochemical properties of the dump site materials. The concern is that compounds in the inactive dump body may become 'mobile ' when the physical and chemical conditions in the rubbish heap change, and this will continue to be damaging even centuries after the dump was filled and revived.

A correct lining and a correct geological environment are basic absolute must-haves for last storages. They're compulsory for containment, for monitoring and, last although not least, for environmental security reasons.

Ditched in a dump, community solid waste ( MSW ) will at last come into contact water, which enters the rubbish heap continuously thru rain, even after capping as the seal can't ever be perfect over a period of time. As a result of this contact, many chemical and microbiological reactions occur. Natural compounds can be modified to other natural chemicals or inorganic compounds. Inorganic compounds can experience many chemical reactions and can be changed to other inorganic compounds.

The products of these reactions and parts of non-reacted MSW can, and at last will, be transported by leachate and by gas into the encompassing area. In addition, many physical processes, like adsorption, dissolution, rain, etc, can occur simultaneously. a MSW rubbish heap can be accepted as a 'partly continued chemical and microbiological fixed bed reactor'. Now that isn't a great thing to have in communication with groundwater which should regularly later be used as drinking water. It is also regarded as therapy facility where the target it is to get it to self-treat to a rubbish heap body of last storage quality. Major research and monitoring of landfills is a new development, controlled landfills having existed for 20 years or so already.

The present controlled landfills so are still in the exhaustive reactor phase in which radical microbiological decompositions occur.

The behavior of landfills in this period can be considered roughly properly using current models. But no experience exists regarding the long term behavior ( over even 30 years ) of MSW landfills. Thanks to the highly difficult nature of the systems, a specific prediction of long-term behavior of MSW landfills is almost impossible. So it's no exaggeration to claim that long-term leachate emissions from city solid waste landfills are unknown, and yet all across the globe each day, new and larger landfills are being built and stuffed with waste. It's all a big experiment and science hasn't determined the result. Even the Swiss, who are possibly some the most responsible guardians of the environment in the world have fallen far short of their 1986 ideals.

How can we be so complacent? Shouldn't we all be worried?

Article is based upon the paper "Long-Term Leachate Emissions from Municipal Solid Waste Landfills, Hasan Belevi and Peter Baccini, Switzerland, presented at the International Symposia on Sanitary Landfills held in Sardinia (Italy)"

Many people find this fact to be of great concern. Is all of landfilling just a huge experiment which might cause huge problems in the future? Part 2 of this article is available were we further discuss landfill final storage quality. Go there now to read more!

Avoiding Relying Too Much on the HELP Model for Forecasting Leachate Generation Rates from Landfill Sites

Uncontrolled Leachate Ponding

There is a method for estimating leachate generation rates. It has been produced by the American authorities to assist in the estimation of leachate production rates for a wide variety of MSW Landfills, and Hazardous Waste Landfills. In itself it represents a good exercise in rationalising the highly complex set of climatic and physical interactions which take place when rainfall incident on a real life landfill becomes leachate.

The problem is that just like any computer model, it produces results by mathematical processes which the average user will never be able to understand fully. To anyone other than academics who have studied the programming of the Model, and then furthermore have verified the calculations which they have produced by using it, against real-life data for existing closely landfills in similar climates, it should be thought of as a “black box”.

Even if the data these users put into the model is good, and that is by necessity rare as landfills are difficult to quantify in the terms that the model requires inputs, and the site operator actually then complies with the “plan” in detail. Also, the average HELP Model user does not get the chance to validate the results for the site in question. So, the results should be considered of doubtful accuracy, and yet leachate management plans are commonly based upon HELP models alone.

The result has been a tendency for leachate management systems designers underestimate landfill leachate generation that starts sooner than expected and is of higher volumes than predicted.

They would do better if landfill engineers would ensure that only HELP Model experienced hydrologists were engaged to do the modelling work, as well.

Unfortunately, there is no easy fix to this problem, and although the experienced hydrologist will know more clearly where his skills end in using the programme, and uncertainties remain, no magic wand can be waived without good verification data available when the HELP Model is run, and a close match can be shown.

The science of leachate volume prediction is not simple, and the methods to predict it need further research. However, landfill designers would do well to appreciate more fully the limits to the tools available for leachate flow prediction, and pass this knowledge on to landfill operators. By making the uncertainty inherent within the predictions clearer, such that more flexibility is provided within leachate management plans, and in forward planning, everyone would be better served.

After all, the lack of availability of an adequate method for controlling leachate can in some cases, over a period of only weeks allow leachate spillages into watercourses and aquifers which may take years to remedy. This may threaten the health and livelihoods of many people and the negative publicity from such incidences will only hasten the demise of the landfill in the long term. If the industry cannot avoid such instances of pollution, it probably should.

This article is supported by a more detailed discussion of this subject, which quotes papers and authors who have written on this subject in the past. Read the full article and if you wish, follow up on this with its sources, at: HELP Model at http://leachate.co.uk/main/

What Is Leachate?

So you want to understand what leachate is? You would be surprised how many people ask that question by seeking the answer from the world wide web. This is why we've created this article to clarify what family or friends might feel you ignorant of, and even stupid for wondering about what they might think was obviously a foolish issue.

An advantage of the world wide web is that you can ask these questions on virtually any topic, and on every occasion without worrying that your buddies think about what you ought to know already about what you are discovering.

So, I want to now get on with giving an answer to your issue about what leachate really is.

First, leachate can be defined as: the liquid (mostly water) which having passed through a mostly solid substance or mixture of substances picks up on its way substances which can be both liquid and solid particles, and runs out at the bottom.

To make that more clear, here is a listing of where leachate may appear, as follows:

- landfill leachate (also known as tip leachate and dump water)
- compost leachate (sometimes called compost tea)
- manure heap leachate.

This really is a bad smelling list, so let's make an effort to de-stress he issues. It may be labeled into the following kinds of leachate,as follows:

- Fresh and smelly leachate is "acetogenic" leachate
- Older leachate from landfills which are a number of years old and is call "methanogenic" leachate, as it comes from methane gas producing landfills which produce landfill gas

The key of such are:

- in the age and the degree of odour which is much worse in the new leachates.

The unique attribute is the fact that leachate is a highly organically contaminated liquid which even in small quantities can harm streams and rivers and make groundwater undrinkable if leachate contaminated water is present in a well.

The important matter, is to recollect about leachate is that it is best to take measures to make sure that making it is avoided, because once a lot of it has been produced it is expensive to dispose of without damaging the environment.

Since you have checked this article out, and have read it to the end, you clearly needed to understand a lot more about leachate, which we hope we will, have aided, you with. As a result of this research you may quite prudently have applied the services of the world wide web wisely to answer a very specific query that it is vital that you at this time resolve. Now, it is possible for you to compliment yourself for what you have learned. By training ourselves, every one of us can obtain greater results in life, and now we undoubtedly desire that you'll do well, as well.

Realize easy methods to minimise, and then if necessary treat, landfill leachate by going to our landfill leachate web site at leachate.co.uk/main.

3 Symptons Which Could Be Caused By Leachate Pollution And Are Worth Looking Out For

It is almost always the case that a problem like leachate pollution can easily be diagnosed and solved by matching the symptoms that you see, to a known problem. In fact that's what a medical doctor spends his time doing every time he interviews a patient. However, the technique isn't just limited to the practise of medicine, it works for all sorts of problems. That is why we have written this article to help you understand what the symptoms of leachate pollution are.

So, before we go any further, here are the three symptoms often experienced when quite severe leachate pollution occurs in a river or stream occurs as the river or stream passes a landfill. 

Sympton No. 1 is the disappearance of the normal water-life. The first to be lost will be fish which can no longer live due to a depletion of oxygen in the water.

Sympton No. 2, which is often seen in such circumstanes is that if flow is quite slow the surface of the water may have a sheen of colour which looks almost like the rainbow colours of oil floating on water. However, if leachate is the cause instead of a flexible coating, this colourful surface layer can be cracked and dispersed by agitating it.

This most often occurs when a high concentration of dissolved iron is leaking into the watercourse, in the leachate.

Sympton No. 3: The final symptom in these cases is that if a water quality sample is taken and the concentration of ammonia is analysed the ammonia will have risen, alongside other contaminants as well, during the passage of the stream or river past the landfill.

This happens when the rain which fell on the landfill decomposes in the landfil, producing high concentrations of ammonia which are very damaging to wildlife if it gets into watercourses.

If you have seen these symptoms of leachate pollution you are lucky, as you now know the diagnosis of the problem of leachate pollution, and knowing the problem is the first, and often the most difficult part of identifying and successfully applying a solution.

Congratulations, you have now found out what is causing these symptoms and the cause of the  problem. Don't stop now. There are many ways in which you can now find the solution to this problem. One method which is used, is to use the internet and continue by using a search engine to identify a website with the solution to this problem, but there are many other solutions such as asking an expert you know, or visiting a library.

Whichever method you use, we wish you a successful search for the solution you seek.

Discover tips on how to prevent leachate pollution at the leachate management site at leachate.co.uk.