3rd Global Landfill Mining Conference and Exhibition 2014
17 - 18 November 2014, London, UK
Dr Robert McCaffrey, conference convenor
Delegates from 16 countries assembled in London on 17 - 18 November 2014 for the 3rd Global Landfill Mining Conference.
Tim Lineham of Ricardo AEA started off the event, stating that by 2050, humankind is going to require 300% more resources than it does now. Critical resources from conventional virgin sources are 'running out,' with less than 10 years of indium, less than 30 years worth of silver and less than 40 years worth of zinc. "As resources become scarce and we increasingly recognise the value in the waste that we generate, surely it would be reasonable to consider that there must be value in the waste currently sat in our landfills?" The first documented modern landfill mining project was at the Hiriya landfill in Israel, which was mined for the soil fraction which was reused on citrus groves, with hand-sorting of oversize materials.
Another 60 landfill mining projects have since been undertaken around the world for a number of reasons, including seven in the UK. The Sandford Farm project in the UK is currently ongoing, and is made viable by the value of the land recovered by landfill mining. In terms of technical issues, high leachate or groundwater levels add to complexity and costs; simple excavation, shredding and screening are well-proven; advanced separation techniques are less proven; the nature of the waste means that breakdown, blockage and wear and tear will be high; low contamination is hard to achieve; nonetheless landfill mining is technically feasible. Tim gave the results of a Scottish study which suggested that landfilling mining would be profitable in the best possible circumstances if the energy was reused onsite and the land was then reused. Waste from the 1960s to the mid-1990s is probably best for mining, as in the case of most successful European landfill mining projects, since it contains the highest proportion of valuable components representing a time before pre-landfilling sorting was common. Local markets are critical in determining economic viability and this will change with time and geography. Knowledge of waste composition of landfills is scarce, but is key to understanding viability of any landfill mining project. Tim concluded that from a circular economy point of view, a landfill is just a temporary storage area for future resources.
Reinhard Göschl of IUT GmbH then spoke about business models for landfill mining. Landfill mining is typically undertaken for environmental reasons, for commercial reasons for example to create new space for infrastructure projects, to create new volume for existing landfill and finally to produce recycled resources out of the content of the landfill. Firstly, the landfill must be examined and explored, usually with the use of eyewitness reports, trial pits and remote sensing. The landfill must be aerated, to reduce the hazard of fires and explosions and to avoid odour and to start an aerobic biodegradation of the waste. The landfill must then be excavated and finally the waste must be processed. The landfill composition will always reflect the level of development of the country at the time of filling. In terms of volume, a landfill might be composed of 32% refilling materials such as soils and clays; 6% that could be sent for recycling such as metals and some plastics; potential RDF makes up 47%; and rejects and inerts make up 14% of the volume. For his fictional business case, the cost of the diesel to operate the machinery was a big factor in the overall cost of landfill mining, while the produced RDF was presumed to be saleable at only 50% of the cost of an equivalent coal KJ, or about Euro38/t of RDF.
Reinhard concluded that the least cost of landfill mining was around Euro30/t, depending on economies of scale and the length of time of the mining operation. He suggested that there would be zero revenue from selling either recovered wood or metals. He also said that, depending on the situation of the landfill, that the land cost could be a powerful driver for economic viability of the project. "Landfill mining," he concluded, "is not economic if it is only financed by the sale of RDF, although government incentives can make a project economically feasible even when the land value is not high enough. Many landfill mining projects have already been completed, so that the information to enable successful projects to take place is out there."
Brett DeVries of the University of Texas spoke about site investigation techniques for landfill mining. Brett suggested that to supply the needs of each American requires the mining of around 10 tonnes of new non-fuel minerals each year. He suggested that American landfill operators are obliged to monitor their landfills after closure at a cost of around $1m each year for each landfill: mining the landfill will avoid this ongoing liability. He suggested that it is important to understand both landfill composition and its variation. Brett spoke about the landfill at the city of Denton, close to Dallas, part of which is being mined to allow the installation of a new liner. Two boreholes have been dug to a depth of around 20m using a bucket auger, taking a sample every 3m or so. Newspapers recovered from depth could be read even after 20 years in the landfill. A compositional analysis showed that food waste is eliminated after 10 years in the landfill, while paper composed around 30% of the mass of the waste sampled in the borehole, depending on the depth in the hole. There was quite a high variation in composition between the two boreholes, even at the same level. The influence of water ingress into the landfill was critical, with the presence of water strongly promoting faster organic degradation.
Greg FitzGerald of Terra Recovery next spoke about landfill site remote sensing. Greg suggested that there is 2bn tonnes of untouched waste in landfills in the UK, that there are around 300,000 landfill sites in Europe and another 1.8bn tonnes of new waste which is landfilled each year around the world. Greg suggested that landfill mining needs to go from a situation where a site is considered largely because you already have a relationship with it ('you own it'), to a situation where a large number of landfill sites are considered and then the most lucrative and profitable are selected and characterised in the first place, and only afterwards investigated with more expensive techniques (such as 'putting your spade into the ground'). An elimination from consideration of landfill sites can primarily be based on the age of the operation, its size and volumes and estimations of content, even before remote sensing might be used. Resistivity, ground penetrating radar and a drone carrying remote sensing sensors will be used for landfill characterisation. Satellite measurements can be used for size and volume characterisation fo the landfill and even to quantitatively measure the evolution of the landfill through time, through biological degradation and methane outgassing. Infrared thermography may be used to detect temperature anomalies to indicate biochemical activities.
Peter Elliott, who is the technical lead on landfills for the Environment Agency (EA), next spoke about the process that a prospective landfill miner would have to go through before starting a project in England. The environmental risks will vary from site to site, but may include emissions of landfill gas, potential emissions to groundwater or to surface water, odours, dust and particulates, litter, fire, vermin, noise and vibration, waste stability and potentially other hazardous materials. Peter suggested that there are two basic landfill cases: those with a permit (1400 in England) or those 20,000 sites without a permit. A permitted site will have many measures in place to control environmental impacts and this could be revised or varied to allow landfill mining - although the treatment of any waste may need a new permit to allow it to take place. The unpermitted sites do not need a permit to allow digging, but in fact almost every aspect of a landfill mining operation on unpermitted land would be covered by planning laws, contaminated land legislation and local council controls. If there is on-site treatment, then the EA would need to be consulted and a permit issued (or not). There is a question mark over the point at which the waste ceases to be waste - in which case the waste might not be re-landfillable, leading to potential problems. The EA has received requests to recover secondary aggregates, to recover foundry sand from a permitted landfill for use in concrete manufacture; and for excavation and redeposit of co-disposal waste from a permitted landfill to make space for an energy-from-waste facility. Requests are currently considered on a case-by-case basis.
Gintaras Denefas from the Kaunas University of Technology in Lithuania next spoke about some of the challenges facing landfill mining in his country. The prevention of contaminants in the Baltic Sea from landfills and dump site in Lithuania has been emphasised in recent legislation and several research projects have been undertaken to try to promote landfill mining, not just in Lithuania but also in other countries bordering the Baltic. A landfill mining project was undertaken at the Kudjape landfill in Lithuania, with manual sorting used to increase recovery of valuable metal fractions, although future research is required for automation of this process. Concrete waste has been profitably recycled from landfills. Gintaras pointed out that under EU funding rules, a closed and 'rehabilitated' landfill cannot be touched for at least five years, although this is within the period of most potent methane genesis, which can be captured and used for energy production.
Tom Behets of OVAM, the Flemish public waste agency, spoke about the government agency's approach to landfill mining. Flanders, in the northern part of Belgium, is highly industrialised and is densely populated, with 472 inhabitants/km2. "The whole country is effectively a suburb of Brussels," according to Tom. A series of policy changes has led to the active promotion of landfill mining in Flanders. The process will be driven by the need to create or to reclaim land for development. At the moment less than 1% of waste is landfilled. Tom suggested that we will soon start to mine the deposits of the Anthropocene, which is the geological horizon of humankind, rich in valuable resources. All 2059 landfill sites in Flanders have been located and mapped, showing that they have a total surface area of 80km2. Tom said that variations in the quality of the mapping data can lead to problems with inter-site comparisons. A decision-support system can be used to rank the landfills in terms of their attractiveness for landfill mining. Tom baldly stated that seismic methods are ineffective for landfill characterisation, but that other geophysical methods (electromagnetic induction, electrical resistivity, ground penetrating radar) are of more use. The vision of Eurelco, the European Enhanced Landfill Mining Consortium, is that by 2020 landfill mining will be implemented Europe-wide as a key component of a resource-efficient, circular and low-carbon economy. Tom stated that the presence of asbestos or glass in the waste can bring problems to processing. A Flemish Brownfield Act that was passed in 2007 including tax advantages for land remediation has led to 800ha of land being redeveloped. Interestingly, one gypsum stockpile (now known as the Terranova solar park) was converted to a solar farm, with an output of 15MW/year, by fitting 55,000 solar panels covering 20Ha to the sides of the phosphogypsum stockpile.
Adelbert Regeling of Keith Walking Floor Europe finished the first day with a presentation on the use of walking floor trailer technology for the transport and unloading of various abrasive materials from landfill mining. Adelbert demonstrated the effectiveness of the technology with the benefit of a number of videos and animations, showing that the system can handle incoming MSW, as well as biomass, RDF, scrapped tyres and even fluff.
A convivial and international dinner took place in the evening with much landfill mining discussion.
Second day
Tom Behets returned on the second day of the conference to give more details of a pilot project for landfill mining in Flanders. Seven criteria were used to determine the attractiveness of a landfill site for mining: the type, period of landfilling, volume, current land use, distance from roads, waterways or railways, proximity of other landfills and the need to remediate the land. Tom said that the need to remediate is a strong criteria for landfill mining, and this can be influenced by the proximity of the landfill to residential, agricultural, industrial, recreational or ecologically vulnerable land, as well as the proximity to surface water, water wells or flood-prone areas. Prior to selection, a prospective landfill mining site must also be considered in relation to its effects on groundwater, and in Flanders every aspect of the landfill mining project must be considered in terms of its risk, not just for humans but also in terms of ecotoxicity. Projects are currently controlled under the comprehensive regional soil remediation legislation. At the Zuiekirke landfill mining project half of the site was mined and fully remediated, while a quarter of the site was mined and allowed for reuse with minor limitations. The final quarter of the landfill was used to stockpile the separated soil fraction which was strongly enriched in heavy metals and which then could not be used without a further (ongoing) phytoremediation process: Crops such as elephant grass are used to selectively uptake elements from the site and the crops are then processed off site and the offending elements captured. Other means for deriving money from landfills include their use for methane extraction, as wind energy parks, for the growth of energy crops, for golf course or other recreational areas, for forestry or other agricultural use.
Claus Warming of Metso Denmark spoke about his company's technology for shredding the difficult waste materials that are derived from landfill mining. Typical landfill waste may contain 'surprises,' such as concrete blocks, railway sleepers, carpets and mattresses, hazardous waste, paint and solvents. Claus suggested that a pre-shredding step should be used to break or crush all voluminous items, which at the same time loosens all mingled materials and shakes off all soil, sand, stone and metal components, in order to make the materials screenable in the downstream equipment. The shredding equipment must be extremely robust, with big and aggressive knives to improved capacity and longer equipment lifetimes. Each of the two shredding shafts in Metso's most popular shredding machine weighs around 5t, and a variety of different knife shapes can be used, depending on the predominant waste types expected. The shredder shafts rotate relatively slowly in both directions, freeing up any blockages and also distributing wear evenly on both sides of the symmetrical knives. The company has installed over 700 shredders on all sorts of projects around the world over the years.
Travis Benn of Accounting for Energy Ltd gave the final presentation at the conference, on revenue audits for landfill mining projects. Travis acts on behalf of landfill operators, to try to maximise the amount of revenue that is derived from renewable energy projects. This may include reviews of contractual agreements, validation of source data, a review of historical receipts versus expectations and the quantification of any underpayments. Carelessness, inaccuracies or fraud may lead to underreported energy production and hence lower than expected payments. He pointed out that landfill gas-based electricity generation is the fourth largest renewable energy sector in the UK, with over 400 sites licensed. The sector is set to expand yet further as the government attempts to increase its renewable energy sector to 20% of the overall total by 2020. Warning signs that not all is well within a project might include that income is late or received only erratically, difficulty in reaching staff and high staff turnover and an inability to receive explanations or supporting evidence for outcomes. When working on a landfill mining project, particularly one with on-site energy generation, revenue audits will be required in order to make sure that the project's finances are kept in order.
Farewells
At the Farewell luncheon, Reinhard Göschl of IuT GmbH was awarded the best presentation prize for his paper on the economics of landfill mining. Delegates then had the opportunity to visit the Thurrock Thameside Nature Park at Mucking, which is a 30m-deep landfill that has been capped and rehabilitated and which is now a popular nature reserve, bird-watching and ship-watching spot on the muddy north bank of the Thames Estuary.
Delegates comments
- My favourite thing was the high level of representatives that spoke and attended.
- Thanks for the conference: the level is always high - congratulations!
- Small but nice mix of attendees.
- Good spread of presentations.
- Overall a good conference.
Discussion and conclusions
After the presentations, delegates were involved in a wide-ranging discussion on whether landfill mining is likely to be a growing trend or if it is forever destined to be a niche activity. As had become clear through the conference, the technical issues with landfill mining have been solved. However, landfills vary enormously, and while some landfills may be mined profitably in the future (mostly the larger, better characterised, well-located projects that had strong controls on what had been put into them in the first place), many other landfill mining projects are literally 'non-starters.' Commodity prices are still too low to pay for the costs of landfill mining on their own. However, governments can give strong impetus to landfill mining by allowing project operators to reclaim the tax that they paid when putting waste into a landfill, when they take that waste back out again - a sort of 'tax mining.' Delegates suggested that the longer-term environmental impact of the vast majority of landfills was much lower than had previously been expected, especially if effective controls were in place to management drainage, meaning that the likelihood is low that landfill mining will be dictated by environmental impact abatement. It was pointed out again and again that the reuse of the land (possibly using it again for landfilling) or resale and redevelopment was by far the most lucrative driver for landfill mining. In countries where land is scarce (or where landfilling is tightly regulated and taxed), this is a strong driver for landfill mining: In countries where landfilling is not strongly regulated, is untaxed or where there is plenty of land (for example the US), then the economic and regulatory drivers for landfill mining are absent or much weaker. A final situation was pointed out though: where local politicians want a landfill to be removed (for aesthetic, infrastructure or just for kudos), it will be done, no matter what the cost. The terminus of a new high-speed railway line in China currently offers passengers a splendid view of a 4,500,000m3 landfill when the doors on the train open: Local politicians have decreed that the landfill shall be removed and have budgeted over US$200m to make it disappear within two years.
If the situation changes, we will be back with another Global Landfill Mining Conference... but until then, adios!
The conference proceedings (presentations and pdf version of the conference book) are available on CD, price £295. Please contact Sonal Patel at This email address is being protected from spambots. You need JavaScript enabled to view it.for ordering details.