Enhancement of landfill leachate treatment using extracellular polymeric substances as bio-flocculants

Fermentation of Klebsiella pneumoniae was conducted using crude glycerol fortified with secondary paper mill sludge as a carbon source in 5 L fermenter. After 96 hours of fermentation, the fermented broth contained mostly microbial cells surrounded by extracellular polymeric substances (EPS) and other particulate residues from paper mill sludge and glycerol. When this fermented broth is used as it is, it is called broth EPS (B-EPS). When the fermented broth is centrifuged, the supernatant solution is separated from the rest of the microbial cells and from sludge residues. This supernatant is called Slime-EPS (S-EPS). Both types of EPS were used for treatment of landfill leachate. S-EPS showed better flocculation activity (85%) than B-EPS (70%). EPS was also used in combination of Al-2(SO4)(3) or FeSO4. The removal efficiency of COD with use of S-EPS combined with FeSO4 (more than 80% of COD removal) was higher than with S-EPS alone (48% of COD removal). Better results were recorded when S-EPS (0.015 g/L) was combined with FeSO4 (2 g/L) at pH 8. A remarkable reduction of the following parameters was recorded: COD (82%), total nitrogen (44%), phosphorus (50%) and removal of metals such as Ca (64.3%) and Mg (62.4%).

Automated summary

Fermentation of Klebsiella pneumoniae using crude glycerol fortified with secondary paper mill sludge resulted in the production of two types of EPS, B-EPS and S-EPS, which were used for treatment of landfill leachate. S-EPS showed better flocculation activity and COD removal efficiency compared to B-EPS when combined with FeSO4.