The anaerobic digestion and composting plant based in Monterotondo Marittimo, in the locality of Carboli, owned by Acea Ambiente uses mainly organic waste from separate collection and sludge generated by wastewater treatment plants. Within the same site, PAL built a fixed compost refining station that was tested in April 2022.To get a better understanding of the plant we interviewed Engr. Andrea Dal Ben, PAL’s General Director, who followed the sale and management of the Project.
The plant consists of a belt with loading hopper that can be fed directly by a wheel loader that allows the loading of material and, thanks to its peculiar shape, doses and feeds the material to a conveyor belt (that can be moved manually to facilitate maintenance) which feeds the rotating screen intended for compost refining.
The screen has a 2.2 m diameter and is 9 m long, and has been intentionally extended compared to the originally planned length so as to cope also with possible peaks of incoming material (guaranteed nominal flow rate is 50 m3/h). The underscreen and the overscreen fractions are unloaded in two areas sectioned off by Lego Block.
Firstly, as mentioned above, we chose to find solutions aimed at guaranteeing the constant flow of the plant without jeopardising screening efficiency, as well as absorbing peaks of incoming material.
For this reason, each machine is fitted with an inverter so as to regulate it in the best possible way. Furthermore, the shape of the infeed belt is such that it promotes the overflowing and dosing of material, a process that is helped by the inverter itself – a fundamental characteristic to achieve good screening – adequately regulating the flow of material and the rotating speed of the screen. It is worth noting that all the structures of the line, as well as the walkways were built in stainless steel AISI 304 to ensure maximum duration over time even in a particularly chemically aggressive environment.
The rotating screen has a centralized greasing system as well as large side doors on the sides that facilitate operator access to control the screening barrel and possible disassembly of the cleaning brushes of the drum itself. In order to guarantee the safety of operators during maintenance, there is an automation and control system that allows the rotation of the drum by only one sixth at a time with consequent locking of the same in position, a standard option in all the rotating screens produced by us.
