BATCH AND REACTOR STUDY ON BIOREMEDIATION OF LIGNIN RICH PULP AND PAPER MILL EFFLUENT WITH BACILLUS CEREUS BACTERIAL ISOLATE

Paper mills generate colored effluents that are rich in lignin and its derivatives. In the present study, an indigenous ligninolytic bacterium, RJH-50, was isolated from paper mill sludge and identified as Bacillus cereus using 16S rRNA sequencing. The bioremediation efficiency of the bacterial isolate was evaluated in terms of lignin degradation, chemical oxygen demand (COD) reduction and color removal using the shake flask method in batch mode and in reactors under semi-continuous mode at different retention times (RT). In batch mode, the bacterial isolate reduced COD, color, and lignin by 57%, 51% and 48%, respectively, after 72 h. In semi-continuous mode, the same parameters were reduced by 58%, 49% and 46%, respectively at a RT of 48 h. The bacterium was able to effectively treat lignin-rich effluent using cost-effective ammonium sulphate as N and phosphoric acid as P source at a relatively low retention time. Thus, it could be considered a promising candidate for treating paper mill effluents.