Production of a novel bioflocculant and its flocculation performance in aluminum removal

ABSTRACT

A novel bioflocculant CBF with high flocculating activity, produced by mixed culture of Rhizobium radiobacter F2 and Bacillus sphaericus F6 from soil, was investigated with regard to its production and flocculation performance in Al(III) removal. The most preferred carbon source, nitrogen source and C/N ratio (w/w) for strains F2 and F6 to produce CBF were glucose, urea and 20, respectively. The optimal inoculum size for CBF production was 10 % (v/v). The optimal initial pH, culture temperature and shaking speed were 7–8, 30°C and 140 r/min for 24 h, respectively, under which the flocculating activity of the bioflocculant reached 98.52 %. According to literature review, flocculant dosage, coagulant aid dosage, pH, hydraulic condition of coagulation and sedimentation time are considered as influencing parameters for CBF flocculation performance in Al(III) removal by L16(4⁵) orthogonal design. The optimal conditions for Al(III) removal obtained through analysis and verification experiments were as follows: CBF, 28 mg/L; coagulant aid, 1.5 mL/L; initial pH, 8.0; and hydraulic conditions of coagulation: stir speed, 160 r/min; stir time, 40 s; and sedimentation time, 30 min. Under the optimal conditions, the removal efficiency of Al(III) was 92.95 %. Overall, these findings indicate that bioflocculant CBF offers an effective alternative method of decreasing Al(III) during drinking water treatment.

KEYWORDS:

• aluminum removal
• bioflocculant
• flocculating activity
• production

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Acknowledgements

The EssayStar Company for their English language editing and the suggestions from the anonymous reviewers are highly appreciated.

Notes on contributors

The experimental work was conducted by Lixin Li, Fang Ma and Huimin Zuo. The manuscript was written by Lixin Li and Huimin Zuo. Data analysis was performed by Lixin Li and Fang Ma. All authors approved the final version of the article, including the authorship list.

Funding

This work was supported Sponsored by the National Science Foundation of China (Grant No. 51478140 & 51408200), the State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology)(Grant No. 2015DX06), the Natural Science Foundation of Heilongjiang Province (No. E201461), the Special Fund for Science and Technology Innovation Talents of Harbin (Grant No. 2015RQQXJ015) and the Promising Youngsters Training Program of Heilongjiang University of Science and Technology (Grant No. Q20120201).