Frantschach Swiecie S.A., the largest Pulp & Paper producer in Poland and one of the larger in Europe, chose to upgrade the existing WWTP with a new floating biological bed equipped with an advanced steering system. The discharge from the WWTP will be one of the lowest in Europe, 4 kg COD/tonne produced pulp, and is already below the future goals for the European Union. The new demands have been reached with an advanced steering system controlling three selective biological reactors operating in series and/or parallel. Each biological reactor is operating at specific conditions to decrease selected organic compounds. The new floating biological bed, FlooBed®, is an upgraded activated sludge system with floating carriers covered with a thin biological film. The FlooBed® reactor is a progress from fluidised beds and modified activated sludge plants.
The activated sludge plant as such has not been rebuilt. The improvement of the activated sludge process is that the wastewater now is saturated with oxygen and new micro-organisms are created before the entry to the existing activated sludge plant.
The FlooBed® reactors are installed in a volume that is 50 % of the former activated sludge plant volume and the reduction of COD has increased from 51 to 90 %. The operational costs for the FlooBed® are 17 EUR/tonne reduced COD where 7 EUR is electricity and the remaining part is added chemicals.