HOW TO RECOVER DUMPED WASTE WITH MECHANICAL SEPARATION
While progress has been made in the past years regarding the management of waste, landfilling will not be eradicated in the near future, for a lot of reasons. Despite enhanced legislation, policy development and regulatory supervision, landfilling is still sought as the simplest solution to get rid of unwanted waste. And unwanted in this case does not mean that it cannot be recovered, all to the contrary…With today’s technology, we can recover materials and energy from landfills, while the land can be used in a smart way, working to the benefit and wealth of the people, and not against them. So, let’s see what the shift is today from old to new mining, or enhanced landfill mining.
What’s going on with landfilling globally and in the EU countries?
According to the World Bank Group report “What a Waste 2.0”, at a global level “2.01 billion tonnes of municipal solid waste is being generated annually, with at least 33% of that not managed in an environmentally safe manner.”
The same report states that in some of the regions such as Sub-Saharan Africa, South Asia, and the Middle East and North Africa more than half of the waste is currently openly dumped impacting the environment and the health of the people. As to the forms of disposal, globally “some 37 percent of waste is disposed of in some form of a landfill, 8 percent of which is disposed of in sanitary landfills with landfill gas collection systems. Open dumping accounts for about 31 percent of waste, 19 percent is recovered through recycling and composting, and 11 percent is incinerated for final disposal.”
If we take a look at the EU states, according to a Eurostat report in 2018, more than a half (54.2%) of the waste was treated in recovery operations, while the remaining 45,8% was either landfilled – a good 38.7%, incinerated without energy recovery (0.7%) or disposed of otherwise (6.3%). Detailed information on the different treatment methods in the EU countries in the figure below:
But some of the waste from landfills can be recovered through the so-called new mining or enhanced new mining whereas different fractions can be claimed and used for further purposes, whilst old landfill mining practices – where the scope of work is that of reducing the volume of the waste mostly through incineration, can be diminished.
The big issues of open dumps or illegal landfills
The problems that an open dump or illegal landfill creates are endless: from causing air, soil and water pollution to poor quality of life for millions of people that live nearby; not to mention the smell they produce and the fact that they take up valuable land that could be used to set-up infrastructure to the benefit of the people.
And it all starts with the lack of segregation of the MSW at source: thus, organic fraction is mixed with all kinds of waste from plastic to aluminum or inerts, such as stone and dust. Then there is a second issue, as often the material is scavenged by informal collectors that try to take out recyclable materials such as glass, plastic, aluminum, or cardboard. So, by the time the waste hits the landfill or even operational plants, the light fraction that could be recovered to produce RDF for example is often contaminated and damaged.
How to get valuable RDF with landfill mining: the challenges
It’s true, there’s no new catch in landfill recycling, it has a history, but there are some critical operational and technological features to consider when it comes to the separation equipment needed to obtain quality fractions to produce mainly RDF nowadays.
First, if we look at an old landfill, the waste has such different dynamics versus fresh MSW: has a different weight, density, moisture, and it’s wet and sticky. Secondly, you need two or three fractions technology to get an accurate separation and thus best results. Third, there is the need to sort the waste in such a precise manner to not shred it, thus maintaining the quality of the materials and, at the same time, avoiding losing some unwanted waste in the fine fraction.
And last, but not least, in some of the countries there are legal boundaries in taking out the waste from open dumps to sorting facilities, so you need technology that can work directly in the landfill. Or, in the case of recycling plants, you need technology to fit into an existing or a new sorting line.
Ecostar’s state of the art technology for new or old landfill treatment: the opportunities
In Ecostar, we have the know-how and experience in landfill mining, with the best results. There are over 150 machines equipped with the dynamic disc screening technology that is working with fresh and old MSW in countries around the world that need RDF to combat the use of fossil fuels. And we are not talking about a technology that fits all, but one that is custom made on the client’s needs: whether the need is the type of material (fresh or old MSW), different fractions, open landfill separation, or inside sorting line – a screener that can work by itself or in line with other technologies.
Whatever the client’s data, the process always ends with the quality of the separation, production efficiency and the quality of the end material. And we have some projects that encompass all these features and advantages, that you can see below:
Taiwan – landfill mining with Hextra mobile screener
This is an open landfill where our DDS mobile screener Hextra 3F is separating the waste into two fractions of 20mm and 200mm, working at a production capacity of 35 t/h.
Thailand – new and old MSW with our stationary screener Hexact in line with other technology.
In this cement plant they are currently building three new lines that are to work 40 t/h per line of fresh and old MSW recovered from landfill, that is treated into obtaining heat and power for the cement production, saving coal buying expenses and at the same time saving the environment.
The layout is different as it starts with an Ecostar Hexact 5000 that works at a 40mm fraction, followed by a wind shifter, and another Hexact 3000 that works at a 120mm fraction. In this case, besides the workflow there is more to underline: the modular structure of the Hexact and the compact size that allowed the client to fit the screeners into the required space, and save up on the structural costs, but not compromising on the productivity needs. And then, there is the low power consumption: Hexact 5000 is equipped with 2 x 7.5 kW engines, while the second screener Hexact 3000 has only one engine of 7.5 kW.
India: old MSW with our stationary screener, Hexact 7000
India wants to put an end to the source of pollution coming from landfills and start clearing the land to develop solid waste facilities. They are using the segregated combustible fractions to convert it into RDF and send it to the cement plants to be used as an alternative fuel to coal.
At the moment, over 20 Hexact machines, different models (4000 – 5000-7000) are working in different plants at a production capacity of 20 to 40 t/h.
The DDS (Dynamic Disc Screening) technology and its advantages in obtaining valuable RDF with landfill mining
In closure, if you are wondering about the advantages of the Ecostar DDS technology in recovering waste to produce RDF here are some of them to consult:
- Ecostar screeners can be equipped with 2 or 3 screening sizes so that the RDF can be refined, removing the small screening sizes of 20 mm such as dust and soil, and the organic fraction as well. Meaning a better separation that does not allow to disperse useful material in the fine fraction. Less inert material also means less wear on the knives of the secondary shredders where necessary.
- The machines are equipped with a self-cleaning and anti-clogging system resulting in lower downtime of the machine and lower maintenance cost.
- The DDS shakes the material that is distributed on the entire screening surface, so it does succeed in separating wet and high-density material from landfills.
- You will benefit from higher production in less space: in general, in the case of MSW, Ecostar machines can work at a capacity from 10 up to 100 t/h, and various screening sizes of 20, 30, 40, 50, 80, 100mm.
- Low power consumption: The DDS needs only 5 to 15 kWh to treat up to 100 tons/h of MSW.
- Zero emissions released during the separation process, thanks to the installed electrical motors.
Segregation at source, municipalities programs and people engagement along with tougher policies and regulatory supervision should be the focus in better controlling and diminishing landfilling but now, recuperating valuable resources from landfills can only be done with the help of innovative separation technology.