Many challenges affect the system of solid waste management (SWM) in Africa and the Middle East, starting from the source of waste generation. First, the general perception of households in the Region towards waste is that of indifference, apathy, or powerlessness, citizens thinking that waste sorting at home would not make any difference, as everything will end up in landfills or in the streets.
Second, low incentives or inefficient cost recovery mechanism makes the SWM in the Region ineffective and creates again skepticism of the population towards waste sorted collection.
In contrast, Mena Region countries set up ambitious targets to cope with tremendous waste accumulation, estimated to double in 2050 (Kaza, Yao, Bhada-Tata, & Van Woerden, 2018).
Household waste sorting and the separate collection seem a long way to go in the Region, but recycling businesses could make a difference in the recycling process by using high-performance waste screening technology, a fundamental tool to set up efficient recycling plants and fight landfill accumulation.
And aiming for environmental preservation does not exclude seeking wealth out of the waste. Cost-effective solutions shall support waste management operators in increasing their margins.
So, how can waste management businesses increase their efficiency and have a higher impact on reaching recycling targets?
High Performance – Dynamic Disc Screen Ecostar
"In a recycling line, operators may bring together various technologies. And among these technologies, the screening machine has a key role in a recycling plant, as it’s responsible for the separation of the materials, thus having an impact on both the quality of the material that enters the next phases of the recycling process, as well on the economic return of the business."
The Dynamic Disc Screen (DDS) is a top of the edge technology developed and patented by Ecostar, offering an outstanding screening performance. It uses a series of rotating shafts with hexagonal or octagonal discs with a flat profile, that shake well the material and prepare it for the separation. The material slides on the screen through the up and down motion of the discs. The material below the screening size (E.g. diameter of 50 mm) passes through the spaces between the discs, while the larger fraction advances towards the end of the equipment.
The motion of the discs optimises the screening quality as the waste is bounced on the entire surface of the screen, preventing long fibrous, stones, and the sticky organic fraction to obstruct the sieving. The result is a separated and clean fraction ready for the recycling process, even in the presence of wet waste.
Moreover, the DDS (Dynamic disc screening) system guarantees not only high quality but high productivity as well, of up to 200 t/h, as the technology separates the material faster (1m/sec) comparing to traditional technologies.
Practically, higher screening performance in quality and volume means fewer resources dumped in the landfill and more tons of materials sold in the market.
For many of our customers, “Dynamic” stands for the flexibility of our screen. Once installed, thanks to the adjustable speed of the axles, it is possible to tune (-/+ 30%) the screening size according to the waste composition and refine the screening performance. If the waste is particularly wet, the speed of the screen can be slow down to ensure that the organic fraction will fall in the space between the discs.
The screening quality can be furtherly increased, identifying the suitable shape of the disc (hexagonal or octagonal) for each material, and the inclination of the equipment, once installed.
For example, the presence of stones is a common challenge for waste management operators that can be managed resorting to an octagonal disc (so the profile of the disc will be sharper) and slightly inclining in the equipment. Consequentially, the stone will do a small “hop” on the disc, and it will not fall in the under-screen or get stuck in the equipment.
Moreover, a single DDS can be equipped with more than one screening size and therefore sort out different fractions simultaneously. A waste management operator dealing with municipal solid waste (MSW), can use the screen to separate the fine fraction (below 10-20 mm) mainly composed by inert, the organic matter (below 50-80 mm), and other bigger recyclables or combustible materials.
The wide range of screening sizes, from 10mm to 350 mm, makes the DDS suitable for many different kinds of waste: MSW, organic fraction for composting or anaerobic digestion, Refuse-derived Fuel (RDF), construction and demolition waste (C&D), metals, cardboard and paper, plastic (separation low density/PET), tires, biomass, waste wood, incineration ashes and inert.
Easy Maintenance and Safe Operations
The DDS technology has an anti-wrapping and self-cleaning system, as the drive shafts are coated with loose sleeves where the rotating disc is mounted. Therefore, the manifolds are free to turn, independent of the shafts, reducing the friction and preventing that the long fibrous material gets wrapped on the shafts. Moreover, in case any material would accidentally get clogged, it can be easily removed by simply inverting the shaft rotation.
Furthermore, to accelerate and improve the separation of materials which are difficult do manage, Ecostar has developed the Hyper DDS (Dynamic Disc Screening) technology. The HDDS technology was especially designed for the treatment of difficult waste containing long and filamentous materials, such as plastic bags or packaging wraps, which can become twisted around the shafts, or plastic bottles that can clog the system and stop the separation process. Thanks to the special flap, Hyper DDS makes it possible to pick up any materials like bags or filamentous materials that are wrapped around the shafts and convey them towards the over screen.
High-performance, low consumption
The DDS is synonymous with higher performance coupled with cost reduction. The efficiency of the DDS technology permits the use of 7,5 kW electric every 4 meters of screening length, and that makes the technology very cost effective in terms of power consumption, saving up to 70% when compared to traditional screening system.
The technological solutions to reach the recycling targets, while helping the recycling industry in staying profitable, do exist. Combined with recycling programmes, and people engagement, it could all lead to a better waste management process in the Region.