Compliance with discharge requirements
Tunnelling & Drilling
Mobility
Flexible on-site solutions
Water and sludge treatment plants for tunnelling, drilling and ground consolidation
From excavation-sludge management to compliant environmental discharge, Tecnoidea designs and builds open-loop water and sludge treatment plants for tunnelling sites. Solutions developed to manage drilling mud, remove suspended solids and neutralise the high pH caused by cement use, supporting compliance with environmental regulations.
Open-loop water treatment in tunnelling: the challenge of compliant discharge
Tunnelling and ground-consolidation operations generate large volumes of wastewater and drilling mud. Because these sites operate mainly on an open loop — discharging directly to the environment or to the sewer — water treatment and discharge compliance become critical operational issues. Continuous contact with cement and shotcrete used for tunnel lining alters the water chemistry, raising the pH to strongly alkaline levels.
In this context, clarification alone is not enough. Additional treatment stages are therefore typically required for pH correction and suspended-solids removal before discharge.
Tunnelling water treatment must not only separate the sludge but also comply with applicable discharge limits, adapting to limited space and the temporary nature of the site.
The Tecnoidea solution
From clariflocculation to tertiary treatment for compliant environmental discharge
Clariflocculation
The excavation water or bentonite slurry is collected and pumped to the static clarifier, where coagulants and flocculants are dosed to destabilise suspended particles and promote floc formation. The sludge settles into the lower cone, while the clarified water overflows at the surface. On open-loop sites, however, this effluent may not yet meet the discharge requirements and needs further conditioning.
Dewatering scaled to the site
The dewatering system is selected according to the scale and sludge output of the site: for large infrastructure works — large TBM (tunnel boring machine) projects — we integrate homogenisation tanks and filter presses to handle high sludge volumes; for small consolidation sites, where a filter press may not be economically justified, we propose the use of dewatering bags (big bags), in which the sludge dewaters passively and the bag also serves as temporary storage prior to disposal.
Tertiary treatment
The water leaving the clarifier may have an elevated pH due to contact with cementitious materials used on site. It is therefore directed to a dedicated neutralisation tank, where either an acidic solution or carbon dioxide (CO₂) is dosed. As it dissolves in the water, the CO₂ forms carbonic acid, which lowers the pH towards neutral conditions.
Tertiary filtration for environmental discharge
Discharge to surface water bodies is subject to limits on residual suspended solids that may not be achieved by settling alone. The neutralised water therefore passes through a tertiary filtration section — using sand filters or rotary drum filters — able to capture the residual fine suspended solids, supporting compliance with discharge requirements.
Products, plants and technologies for the Tunnelling & Drilling sector
From the complete containerised plant to passive dewatering for small consolidation sites.
Centralina di flocculazione monocamerale
Compattezza e funzionalità per le piccole portate. La centralina monocamerale è la soluzione Tecnoidea per la preparazione e il dosaggio...
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Centralina di flocculazione tricamerale
La centralina di flocculazione tricamerale è la soluzione Tecnoidea per la preparazione e il dosaggio del flocculante in impianti con...
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Impianto di neutralizzazione pH
L’impianto di neutralizzazione interviene come trattamento terziario dell’acqua chiarificata quando questa presenta un pH troppo elevato. Attraverso il dosaggio di...
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Flocculazione
La flocculazione è il processo chimico-fisico essenziale per garantire l’efficienza del trattamento delle acque e, in particolare, la separazione solido-liquido....
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Processi terziari e sistemi accessori
Il completamento di un ciclo idrico chiuso e la massima resa di un impianto dipendono anche dall’efficienza dei processi terziari...
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Vertical static clarifier
The vertical static clarifier is Tecnoidea’s preferred technology for separating suspended solids from wash water. Based on the principle of...
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Sidebar filter press
Designed for the mechanical dewatering of sludge in standard and medium-output applications (with a capacity of up to around 3.3...
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Overhead-beam filter press
The Tecnoidea overhead-beam filter press is designed for mechanical sludge dewatering in high-output applications. It separates the water from the...
Discover the productpH neutralisation plant
The pH neutralisation plant is used as a tertiary treatment stage when clarified water has an excessively high pH. By...
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Palletised chemical dosing unit (CPDC series)
The Tecnoidea palletised dosing unit automates the preparation and injection of liquid chemical reagents such as coagulants, antifoam agents and...
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Contact usWhy choose Tecnoidea’s solutions for water and sludge treatment in tunnelling and drilling
Specialist expertise
Since 1981 we have designed water and sludge treatment plants. In the tunnelling sector, we specialise in managing excavation water with altered pH and high-density bentonite sludge. We manage the entire physicochemical cycle — from primary conditioning to dewatering — adapting the treatment process to variations in ground conditions.
On-site engineering and modularity
Tunnelling projects require mobile and relocatable plant solutions. Space is often limited and the plant must be able to be dismantled and moved once the work is complete. We do not just supply plants; we engineer the complete plant integration: containerised solutions, modular structures and an adaptable range from large clarifiers to simple dewatering bags for smaller sites.
Operational continuity and service
In tunnelling, a stoppage in the water and sludge treatment system can interrupt site operations. Our service is structured to support rapid intervention: we have our own warehouse with spare parts in stock and provide remote support. Our technicians can connect to the PLC to adjust dosing or restore plant operation without having to travel to the site.
45
Years of experiencein process water and sludge treatment
370
Water and sludge treatment plantsfor tunnelling and drilling installed in Europe and worldwide
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