>95%
of process
water recycled
Road Sweeping
Excavation and demolition aggregates
Swiss
Amrein AG
Integrated dual-line water and sludge treatment plant
A complete plant developed in response to new regulatory restrictions
6.2 m³/cycle
of pressed sludge produced
(Line A – aggregates)
1.5 m³/cycle
of pressed sludge produced
(Line B – drilling sludge)
Founded in 1959, Amrein AG is a third-generation family business that has grown from building forest roads to managing the complete materials cycle. Today the company operates in three well-defined areas: Construction (road works and civil engineering), Waste Management (operating an inert-waste landfill) and Recycling (recovering materials from demolition and excavation for reuse). Amrein chose to move from traditional resource management to a more sustainable, circular operating model, in line with Swiss environmental regulations and the growing environmental awareness of the Swiss market.
The project challenges
Swiss regulations
Between 2016 and 2018, regulatory changes in Switzerland restricted the traditional disposal of sludge in settling ponds, requiring the adoption of closed-loop treatment systems.
Company landfill
The company’s own landfill was approaching its capacity limit; without a substantial reduction in sludge volumes, the available landfill capacity would have constrained future operations.
Wastewater management
There was a need to treat both the demolition and excavation aggregates (Line A) and pumpable liquid sludge (slurry) with a high concentration of fines, bentonite and clay from geothermal and drilling activities (Line B).
Tecnoidea’s process-engineering approach
Two integrated lines
Under the engineering direction of metcam, Tecnoidea supplied a plant divided into two independent lines (one for aggregates and one for geothermal sludge), with recovered water exchanged between the two lines through storage tanks to maintain the overall water balance.
Dedicated filter presses and lime dosing
Line A uses an overhead-beam filter press; Line B uses a sidebar filter press configured for liquid drilling sludge. Both lines are equipped with a milk-of-lime dosing system to condition the sludge and improve its filterability, particularly for complex mineral materials such as bentonite and natural clays.
Tertiary treatment and automation
The water undergoes tertiary treatment for pH correction (through neutralisation with CO₂) and sand filtration and activated-carbon filtration; the entire process is managed by an automation system with real-time remote monitoring and control.
Results
Water recovery
The plant consistently recycles over 95% of the water and even integrates rainwater collected from the shed roofs into the closed loop (e.g. over 70 m³ in a single night).
Spadeable sludge
The two Tecnoidea filter presses dewater the sludge into solid, easily handled filter cakes, reducing sludge volume and extending the operating life of the company’s landfill.
Best Available Technologies
By eliminating routine discharge to the sewer, the plant reduces water consumption and wastewater disposal requirements, and it is built on best available technology (BAT) recognised at European level.
Automation and training
Despite the engineering complexity, the automation system simplified plant operation and supported operator training from the initial commissioning phase. The proximity of metcam AG’s spare-parts warehouse in Perlen, 15 km from the site, also supports rapid service response.
“From the outset, I was clear that the most critical part would not be the washing or classification of the aggregates, but the water treatment. That is where the real challenge lies. That is why I wanted someone with deep experience: Tecnoidea was the right choice.”
Beat Amrein, third-generation owner.