Wastewater recovery for board manufacturing

The fibreboard industry is confronted with rising environmental requirements, increasing water and energy costs, and the need for stable, high-efficiency production processes.

Large volumes of wastewater are generated during chip washing, screw press de-watering, refiner preparation, and wet electrostatic precipitation systems. At the same time, fibreboard production depends heavily on steam, traditionally produced using large quantities of fresh water.

A new system from Schrader Verfahrenstechnik GmbH addresses these challenges through an integrated, industrial-scale evaporation and energy recovery concept that enables full wastewater re-use and significantly reduces operating costs.

The system is engineered as a turnkey solution and is customized to plant-specific conditions such as wastewater composition, capacity and energy integration. Its modular design allows smooth integration into existing fibreboards lines while ensuring continuous operation and high availability.

By converting wastewater streams into reusable process steam, the Schrader system transforms a cost-intensive by product into a valuable resource.

System benefits

Wastewater first undergoes mechanical pre-treatment to protect downstream thermal components and ensure stable operation. Coarse solids are removed via curved screens, followed by fine solid separation in high-performance decanters. These solids are de-watered and transported directly to the energy plant, where they are used as fuel.

A large buffer tank equalizes load variations caused by production changes, ensuring constant feed conditions for the evaporation stages, and preventing fouling, scaling, and frequent start-stop cycles.

Thermal treatment is carried out using a falling film evaporator with an integrated steam separator. Mechanical or thermal vapour re-compression increases the vapour temperature by approximately 6 K, allowing the recovered vapour to be reused as heating steam within the system.

This significantly reduces live steam demand and improves overall energy efficiency. The pre-concentrated wastewater is then further treated in a final concentrator, where it reaches a dry matter content of approximately 20-25%.

Energy integration

The concentrated wastewater and separated solids are fed into the energy plant, where their calorific value is fully utilized. Condensate from the evaporation process is routed to a natural circulation evaporator, which generates high-quality process steam using thermal oil or live steam.

This steam is returned directly to the refiner and fibreboard production process. The condensation energy of the energy plant’s live steam is recovered through heat exchangers, and 100% of the condensate is returned to the energy plant. This closed-loop configuration eliminates the need for fresh water in steam generation.

The Schrader system is highly automated and equipped with pre-programmed cleaning-in-place cycles that minimize downtime and chemical consumption. Remote monitoring via Schrader Supervision provides real-time data, supports predictive maintenance, and enables fast fault diagnosis by experienced engineers.

The result is a zero-liquid-discharge solution that delivers maximum resource efficiency, long-term operational stability, and compliance with stringent environmental regulations. That makes it a technically advanced and economically sustainable choice for the fibreboard industry.

 

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