Influence of bovine blood with methylation and polymerization on flocculation of kaolin and hematite suspensions

Session: General Poster:  

Flocculants are used in the primary step of industrial wastewater purification to precipitate solids. Bovine blood is a waste product from slaughterhouses, and there is limited evidence in the literature demonstrating that it can be used as a flocculant. The purpose of this study is to more rigorously evaluate bovine blood as a flocculant and to investigate possible modifications to improve its flocculation efficacy. Native bovine blood (NBB) and two types of chemically modified blood (methylated bovine blood (MeBB) and polymerized bovine blood (PolyBB)) were tested against kaolin and hematite suspensions. Flocculation tests and zeta potential measurements were used to study how performance varied with suspension pH and flocculant dosage. NBB and PolyBB performed well with kaolin suspensions only at pH ≤5.5, while MeBB showed high and consistent performance, indicating pH insensitivity in the range from 4.5 to 8.5. pH was set at 5.5 for flocculant dosage tests. A 20 mg/g kaolin dose of MeBB resulted in 98% precipitation in an hour but performance decreased when more than 30 mg/g was added. Since the isoelectric point of MeBB was much higher than pH 5.5, more positive charges of MeBB could attach to the kaolin particles to decrease electrostatic repulsion compared to the BBN. The performance of MeBB with hematite suspensions was poor at all tested doses (2-100 mg/g hematite), whereas a 30 mg/g dose of PolyBB showed 81% precipitation in an hour due to its negative charge and larger molecular size. Based on those results, MeBB was more pH independent and dose effective compared to NBB in the kaolin suspension, and PolyBB was effective in the hematite suspension. Therefore, bovine blood has potential as a high performance, bio-based flocculant for wastewater treatment.