Treatability studies of black liquor by upflow anaerobic sludge blanket reactor

Abstract

Treatment of recalcitrant organics through cometabolism is well precedented in the literature. The present work deals with the feasibility studies of anerobically treating black liquor (BL) along with the readily degradable synthetic wastewater (SWW) in a bench-scale upflow anaerobic sludge blanket reactor (UASBR). Treatment has been carried out in four phases of operation. In the first phase, 100% of SWW prepared from molasses was used. In the other phases of operation, 10%, 20%, and 30% of the SWW chemical oxygen demand (COD) was replaced by BL COD successively. In each of the operation phases, the composition of the feed was not changed until COD reduction and gas production were stabilized. The entire operation took 509 d. The results indicate that (i) the COD removal efficiency exhibited a decreasing trend with increase in the percentage of BL and (ii) apparently, UASB cannot be used as a treatment option for SWW containing more than 20% BL.Key words: black liquor, upflow anaerobic sludge blanket reactor (UASBR), synthetic wastewater, loading rate, anaerobic wastewater treatment.