Molecular weight distribution in a membrane bioreactor for dairy effluent treatment

The membrane bioreactor (MBR) is one of the most promising processes for the treatment of high organic load wastewaters, as dairy effluent, providing the generation of an effluent with high quality, which could be reuse directly or after tertiary treatment. The aim of this study was to evaluate a MBR to treat effluent from the dairy industry and to use molecular weight distribution of the feed, permeate and the soluble fraction of the sludge as a tool for investigating the mechanisms of pollutants removal in the system. The MBR has proven to be a viable system for the treatment of the effluent in question, with removal efficiencies of chemical oxidation demand (COD) and color of 98 and 99% respectively. Through the molar weight distribution it was possible to observe the high biodegradation capacity and stability provided by the MBR, as even in situations of constant change in feed characteristics, the mixed liquid always showed low concentrations of pollutants. It is also highlighted the importance of the membrane in the system, which, besides allowing the complete retention of biomass and operation with high solids retention time and suspended solids concentration, it can provide the retention of compounds which were not biodegraded, contributing to the generation a treated effluent with high quality.