Flocculation of Coal Waste Slurry Using Bioflocculant Produced byAzotobacter chroococcum

Abstract

The flocculation technique is the most common sedimentation method for the dewatering of coal waste slurry, which is fine grained and has high ash content. Bioflocculants are flocculants which are vital to accelerating the settling of coal waste slurry via the flocculation technique. In this work, the bioflocculation of coal waste slurry was studied using a biofloccuant produced by Azotobacter chroococcum. Quartz and clay minerals were used for comparison. Flocculation tests showed that the bioflocculant effectively flocculated coal waste slurry. Approximately 83% of the flocculation rate was achieved at a bioflocculant dosage of 80 mg/L when the coal waste slurry concentration was 30 g/L. The maximum flocculation of coal waste slurry occurred around pH 2. The flocculation of clay minerals and quartz under the same conditions indicated that the bioflocculant flocculated clay minerals effectively and efficiently, but quartz was scarcely flocculated. ζ-Potential measurements showed that the surface charges of demineralized coal, clay minerals, and quartz became more negative after interaction with the bioflocculant. Adsorption tests and FTIR analysis results suggested that the bioflocculant shows a higher affinity to the demineralized coal, kaolinite, and illite than to quartz. Quartz had a negative impact on coal waste slurry flocculation with the bioflocculant.

A bioflocculant from Corynebacterium glutamicum and its application in acid mine wastewater treatment

“…Moreover, the maximum flocculating activity of the bioflocculant observed at pH 2.0 was similar to that of the bioflocculants produced by Bacillus sp. F19 (Zheng et al, 2008), Bacillus aryabhattai PSK1 (Abd El-Salam et al, 2017) and Azotobacter chroococcum (Yang et al, 2017). Kaolin clay particles form an electrical double layer at the solid-water interfaces and the negative charge on the surface of the particles enables them to suspend well in the solution.…”

Preparation, Performances, and Mechanisms of Microbial Flocculants for Wastewater Treatment

“…Coal waste slurry Azotobacter chroococcum [44] Coal slurry Rhodopseudomonas spheroides [45] Coal-water slurry…”

Evaluation conditions to treat slime water with coagulant-bioflocculant by orthogonal design

“…However, it faces large dosage and secondary pollution problems, so the research and development dosage is small, and the flocculant without secondary pollution is incredibly concerning. Among them, microbial flocculants are interesting because of their excellent flocculation effect, and they are biodegradable and non-toxic, and harmless to the human body and environment (Yang, Wang, & Liu, 2017;Nguyen, Klai, Nguyen, & Tyagi, 2016;Singh et al, 2017) microorganisms during active metabolism and cell lysis. These molecules can flocculate suspended solids (SS), cells, and colloid materials (Lian et al, 2008).…”