Applied Microbiology and Biotechnology

, Volume 100, Issue 12, pp 5653–5660 | Cite as

Synergistic effect and mechanisms of compound bioflocculant and AlCl3 salts on enhancing Chlorella regularis harvesting

  • Chaofan Zhang
  • Xiansheng Wang
  • Yao Wang
  • Yunbao Li
  • Dandan ZhouEmail author
  • Yanwu Jia
Bioenergy and biofuels


The high energy input required for harvesting microalgae means that commercial production of microalgal biodiesel is economically unfeasible. In this study, we investigated the flocculation efficiency and synergistic mechanisms of novel coupled flocculants, AlCl3 and compound bioflocculants (CBF), to overcome this difficulty. AlCl3 flocculation was found to be very sensitive to pH, and flocculation efficiency increased from 55 to 95 % when pH increased from 4 to 10. CBF was environmental friendly, less reliant on pH, but had a relatively low flocculation of 75 % in optimum conditions. The harvesting efficiency of Chlorella regularis can achieve a satisfactory level of 96.77 % even in neutral conditions, with a CBF dosage of 0.26 g/L, AlCl3 dosage of 0.18 g/L, and coagulant aid (CaCl2) dosage of 0.12 g/L. Interestingly, compared with the use of single flocculant, the dosage of CBF, AlCl3, and coagulant aid (CaCl2) were reduced by about 52, 49, and 66 %, respectively. Besides, the aluminum (Al) ion content of the supernatant decreased significantly to a residue of only 0.03 mg/L, therefore meeting the downstream process needs easily. Patching and bridging played key roles in coupled flocculant flocculation, in which AlCl3 mainly carried out the electrical neutralization. This work provides new insight into an efficient, economical, and environmentally friendly protocol for microalgae harvesting.


Microalgae Coupled flocculants Flocculation efficiency Mechanisms Chlorella regularis 



The authors are grateful for the financial support from the National Natural Science Foundation of China (NSFC NO. 51578117), the Development Plan Project of Science and Technology of Jilin Province (20140101006JC) and the Fundamental Research Funds for the Central Universities (2412016KJ011). Moreover, we appreciate the Rhizobium radiobacter (F2) and Bacillus sphaeicus (F6) strain supplied by the Heilongjiang Environmental Biotechnology Key Laboratory of China.

Compliance with ethical standards


This study was funded by the National Natural Science Foundation of China (No. 51,578,117), the Development Plan Project of Science and Technology of Jilin Province (20140101006JC) and the Fundamental Research Funds for the Central Universities (2412016KJ011).

Conflict of interest

The authors declare that they have no competing interests.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Informed consent

Informed consent was obtained from all individual participants included in the study.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Chaofan Zhang
    • 1
  • Xiansheng Wang
    • 1
  • Yao Wang
    • 1
  • Yunbao Li
    • 1
  • Dandan Zhou
    • 2
    Email author
  • Yanwu Jia
    • 3
  1. 1.Key Laboratory of Groundwater Resources and Environment, Ministry of EducationJilin UniversityChangchunChina
  2. 2.School of EnvironmentNortheast Normal UniversityChangchunChina
  3. 3.Norendar International LTD.ShijiazhuangChina

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