Toihan designs, implements and maintains automated control logic for pulp, board and paper mill wastewater treatment plants. Our core mission is to enhance process control with modern cloud-based information technologies. We deliver our mission with a concept called Minimum Effluent Strategy.

Minimum Effluent Strategy in modern pulp and paper industry wastewater treatment focuses on achieving significant effluent load reductions to waterways with improved process control.

Key features of Minimum Effluent Strategy:

  • Resource efficient operation
  • Increase of autonomous control
  • Implementation of new metrics for collecting data on process responses


Resource efficient operation means, that mills have an opportunity to decrease chemical and energy consumption without risking the final effluent quality. With improved timing and accuracy of set process adjustments, the gained operational savings costs are often significant.

Process adjustment setting is supported by proactive PAULA-WWTP®control logic, that can be connected to mill automation. The primary targets are:

  1. Reduce final effluent load to environment
  2. Increase automation in process control
  3. Stabilize wastewater treatment process performance
  4. Generate operational cost saving

PAULA-WWTP® utilizes modern cloud-based data architecture between mill process data and Toihan Cloud, where predictive algorithms convert raw data into meaningful insights and adjustment setpoints.

To confirm that control adjustments are effective, biosludge structural development is monitored closely with computer vision application called FLOCMARK®, which is provided to mill users as a standalone application. The control of good biosludge structural quality is in high importance for efficient process performance. Systematic and objective recording of biosludge structural development beyond human capabilities are needed to open opportunities for minimizing operational costs.


The concept is being tested daily, and it is delivering significant improvements for the industry. Reported benefits include:

  1. No major disturbances in wastewater treatment process operation
  2. No exceeding of permit limits
  3. Maximize color removal
  4. Increased process control transparency
  5. Easier to make bigger adjustment changes
  6. Operational cost savings up to 300 k€/a depending on mill size

Improvements in final effluent loads (kg/ADt) after implementation of Toihan concept are demonstrated with three cases shown below (Hannukainen et al. 2021):


  Period (months) COD TSS Phosphorus Nitrogen
MILL A 4 -22% -61% -21% -49%
MILL B 12 -32% -68% -12% -43%
MILL C 12 -9% -48% -29% -51%


Since these early achievements, Toihan has partnered with multiple mills and continue developing the core technologies even further. With a variety of SUPPORT SERVICES we make sure that our customers are on their path towards the era of intelligent wastewater treatment.