Degradation of industrial tannin and lignin from pulp mill effluent by aerobic granular sludge technology

Tannin and lignin from pulp and paper wastewater (PPW) are two compounds that have been proven to cause a variety of toxic effects in several aquatic species. Aerobic granular sludge (AGS) technology has emerged with strong potential to provide the desired treatment. This work presents the first attempt at the microbial degradation of these compounds using AGS technology, with promising results. Granules were cultivated within 9 days of operation of the sequencing batch reactor (SBR), with SVI30 of 51.6 mL/g, achieving steady-state within the first three weeks of operation. On average, COD removal efficiency was 90%. Granules cultivated from the SBR were transferred into a batch system with real pulp mill effluent. Tannin/lignin removal efficiency was 97% at an initial concentration of 50 mg/L, and slowly decreased to about 60% when the influent concentration increased to 100 mg/L. The most prominent species responsible for the degradation of these toxic substances were Pseudomonas, Corynebacteriaceae and Flavobacterium. These key findings demonstrate the capability of AGS to provide adequate treatment for PPW.