Many authors have studied ultrafiltration as the primary treatment method to remove dissolved and colloidal substances (DCS) concentrated during unbiologically treated white water recovery. The results show that DCS is considered to be the main membrane contaminant in pulp and paper mill wastewater (white water).
However, when UF filtration is used as a tertiary treatment after biological treatment in paper mills, the analysis of membrane contamination processes has not been extensively studied. Therefore, this paper focuses on the analysis of UF pollution after biological treatment, because it can change the organic matter present in white water, and in addition, it can generate new organic matter from biological sludge. Therefore, a full understanding of the properties of substances present in these waters may be helpful in helping to minimize membrane contamination, aiming to obtain high-quality water from UF filtration, thereby reducing freshwater use. Furthermore, in the literature, studies on pollutant properties have received little attention compared to studies focused on membrane properties and water quality. In this work, the problem of membrane contamination, substances retained on membrane surfaces or in membrane pores, and the analysis of DCS in biological wastewater are presented.