The pulp mill in Uruguay, South America, was designed and built by the Finnish company, the second largest pulp producer in Europe, which operates 5 additional plants in Finland. The pulp mill started its operation in November 2007. It is located 5.2 Km away from the city of Fray Bentos, next to the Uruguay River. The production capacity expressed in air dry ton (ADT) per year is 1.3 million. The pulp mill uses the chemical Kraft process. The pulp mill discharges an average annual of the 25m3/ADT about of 73,000m3/day of liquid effluent. They are generated in different processes of the plant and the main flow is from the bleach plant which is directly sent to the WWTP. The WWTP consisted in a mechanical pre-treatment and/or a chemical precipitation primary treatment followed by a biological activated sludge treatment.

The main objective of the present research is to model the current performance of the whole WWTP (including chemical precipitation process) to carry out a model-based assessment of different operational and configuration alternatives to enhance the plant performance and efficiency.