MSW (Municipal Solid Waste) and biomass screening

This article uses real information from a municipal solid waste treatment and compost pretreatment plant where a traditional 8-meter disc screen was replaced with an Ecostar dynamic disc screen in the same size, an Hexact 8000 model, equipped with DDS – Dynamic Disc Screening technology.

With Hexact at work, treating MSW (Municipal Solid Waste) and biomass, the client got greater satisfaction in terms of performance, solving some of the old issues encountered with the previous screening machine. Thus, let’s see how Hexact 8000 performed in this specific treatment line, taking a look at four indicators:

DISC WEAR

The traditional discs screen previously installed suffered from rapid wear due to abrasion caused by the material being processed. Whereas the discs used on the Ecostar screens are made from Hardox, the top-of-the-range in wear-resistant steel, meaning higher endurance.

BLOCKAGES AND TWISTING

The existing disc screen had to stop frequently due to the incoming material containing branches, sticks, stones, packaging reels, and tapes, which were getting stuck between the shafts or twisted around the discs. And this meant frequent downtime of the machine, leading to longer time spent in maintenance and, consequently, higher maintenance costs.

By using an Hexact 8000 with both Ecostar technologies installed – DDS (Dynamic Disc Screening) and HDDS (Hyper Dynamic Disc Screening), specially developed to minimize any twisting and clogging issues, the client got – 90% of maintenance costs/year. The difference is coming from a reduction of the maintenance hours; while the Ecostar screen required 60 hours/ Y of maintenance, the previously installed traditional discs screen needed 600 hours.

HIGH ENERGY CONSUMPTION

As a result of frequent twisting and blockages, the traditional disc screen installed required high power to move the materials along the screening surface. In this specific case, our customer’s disc screen had a power consumption of 40.5 kW/h.

With the Hexact dynamic disc screen, the client managed to have -63% of energy consumption, as the DDS technology reduces the traction force needed to screen the material, thus allowing us to use, on all Hexact screens just one 7,5 kW electric motor for every 4 meters in length. In this specific case, the installed Hexact 8000 uses just two electric motors for a total power output of 15 kW/h.

SCREENING

When screening the pre-treatment waste from the composting plant, the customer found there was excessive moist material in the overscreen. On the other hand, regarding the municipal solid waste, the fine fraction was contaminated with plastics, such as film, straps, and plastic bags.

With the Ecostar screen, the customer can now better separate bags in the organic waste from any organic waste residues and deliver material that is typically drier to the secondary shredders, thus increasing their capacity and decreasing wear. In addition, the percentage of contaminants in the usable fine fraction decreased by 15%, therefore increasing actual production.