Studies on Water Quality Parameters during Ultrafiltration of Kraft Black Liquor

摘要

In this study, a sample of Kraft Black Liquor (KBL) is assessed for different water quality parameters (namely, BOD, COD, turbidity, pH, total solid, oil and grease, etc). Pretreatment methods like centrifugation followed by microfiltration (MF) have been used prior to ultrafiltration (UF) to remove any traces of suspended solids to minimize the chances of membrane fouling. These pretreatment steps proved to be highly efficient in restoring the water flux completely in all the cases of experimentation. The performance of KBL ultrafiltration using batch stirred rotating disk module has been analyzed in this study under different sets of working conditions. The flux enhancement and the reduction of concentration polarization phenomena have been observed with membrane rotation in this shear enhanced dynamic UF module and correlations have been drawn with different operating variables like trans-membrane pressure (TMP), stirrer speed and membrane rotation speed. Asymmetric cellulose triacetate membrane of 5000-molecular weight cut-off has been used for the purpose of experimentation. A very good reduction in each of the aforementioned water quality parameters including nonbiodegradable BOD has been observed and it has been concluded that at one hand, ultrafiltration of KBL with necessary pretreatment can produce good disposable quality water and at other hand, can provide a potent method for recovery of lignin.