Abstract

The waste crisis has become a global issue, forcing many industries to reconsider their disposal methods and environmental practices. When examining the brewery industry, it produces a significant amount of sludge with a high water content. To avoid landfilling, this waste can be thickened to recover valuable materials. This process typically involves the addition of metal based coagulants. In this case, the desired outcome of the brewery sludge would be to produce animal feed. The use of biopolymers like chitosan which act as a coagulant can safely thicken the sludge without leaving toxic residuals. Chitosan is a by-product from the shellfish processing industry and therefore reduces its environmental imprint by using the waste from one industry to treat the waste from another. The objective of this research is to study the effect of using chitosan with coagulation-flocculation on brewery sludge, specifically its mechanisms relating to settling, turbidity and solids removal while applying different dosages and molecular weight biopolymers. It was found that the bridging and charge neutralization mechanisms allowed the high molecular weight chitosan to remove 97% of turbidity within 30 minutes of sedimentation with a dosage of 420mg/L. Its solids classification also produced an overall greater solids removal. The low molecular weight chitosan yielded lower contaminant removal, but settled faster. These results are linked to the Sludge Volume Index as increasing the molecular weight of the chitosan results in a higher index. Overall, the use of chitosan could be a safe and effective way to thicken the brewery sludge.