Putzmeister and Tratolixo: generating energy and composting through urban waste

The waste treatment plant that Tratolixo operates in Abrunheira , near Lisbon, has been managing the waste of nearly one million residents in the western part of the city since 2012, specifically from the municipalities of Cascais, Oeiras, Mafra, and Sintra. This plant is the largest in Portugal, with a processing capacity of 75,000 tons per year , producing electricity and compost through anaerobic digestion.

How does the process work?
The plant receives municipal solid waste, which is added via a conveyor belt to Putzmeister feed hoppers specially designed for the client. Directly below are THS 2052 MX mixing screw conveyors and KOS 1480 twin-piston pumps that pump the waste into three digesters, each with a capacity of 35,000 tons per year, where the fermentation process takes place, generating methane gas.

At the same time, some of the fermented residue in the digester is recirculated by other Putzmeister KOS 1070 piston pumps to mix with more residue and return to the digester . The methane gas generated in the process is stored in a gasometer at the same plant or converted into electricity that is fed directly into the grid.

Everything is used at Tratolixo; the waste from the digesters is analyzed every day, and when it is considered that it no longer meets the properties to produce gas, it is transformed into compost for agriculture.

Likewise, wastewater is taken to a treatment plant before being reintroduced into the plant, as it is not suitable for human consumption.

Putzmeister technology and Maquinter service, keys to success.
In this type of project where biomass, biological waste and food waste are pumped, it is vital to have leak-proof and fault-free pumps and feed lines, since anything that disturbs the transport flow can lead to obstructions or blockages.

Putzmeister has extensive experience in biomass transport since the late 1980s. Tratolixo already relied on Putzmeister technology in two other lines at this same plant since its inception in 2012, and now in 2024, due to increased production, it is expanding to a third line.

Specifically, at Tratolixo's Abrunheira plant, three KOS 1480 P piston pumps operate in the feeding section and three 1070 model pumps in the recirculation section . The KOS models consist of a robust hopper for material feeding, two reinforced delivery cylinders with one piston each, and the so-called S transfer tube, which performs the transfer using two powerful piston cylinders. Therefore, pumping foreign objects and dry or viscous material presents no problem.

For its operation, Tratolixo has three HA 55 E open-circuit, electrically driven hydraulic units and an SEP 55 P control panel . In addition, the lines also have three material receiving hoppers designed by Putzmeister according to the needs of this plant and three pieces of equipment.

Putzmeister THS 2052 MX kneads the initial mixture intensively using auger screws so that the pumps can assimilate the residue more easily.

Although Putzmeister equipment is designed for minimal wear, some wear is inevitable, and Tratolixo relies on Maquinter, Putzmeister's distributor in Portugal, for maintenance and spare parts. This is undoubtedly a decisive factor in their continued trust in Putzmeister technology.

Every year, Maquinter's team of technicians travels to the Abrunheira plant to carry out thorough preventative maintenance, crucial for the system's longevity. Furthermore, Maquinter played a vital role in the entire technical advisory process for the system's commissioning, providing its expertise to the engineers who designed the project.