Development of a Methodology for Sizing Activated Sludge Reactor Volumes for Treating Wastewater from the Recycled Paper Industry

Although the activated sludge system has been in use since the last decade, many industrial typologies still lack a precisely adjusted equation for sizing the optimal volume of these reactors. In response to the need for obtaining size parameters for activated sludge reactors used for treating effluents from the recycled paper industry, a new procedure, in batch mode, reactors were tested at 20°C under different hydraulic retention times (HRT) and 3 ranges of mixed liquor volatile suspended solids (MLVSS) concentrations. Kinetic equations for removing BOD5 and COD were obtained, along with a model equation for calculating the volume of activated sludge reactors. Removals above 90% for BOD5 and COD were achieved with 72 hours of aeration and MLVSS concentrations above 4 g L-1. This new method with standardized equations specific to recycled paper industry wastewater can be considered validated and ready for use by users such as undergraduates and graduates, as well as wastewater treatment plant designers. Finally, it is advisable to use aerobic biological sludge from textile mills for inoculation of activated sludge systems in the paper industry.