TY - JOUR
T1 - Microalgae biomass harvesting by bioflocculation-interpretation by classical DLVO theory
AU - Ndikubwimana, Theoneste
AU - Zeng, Xianhai
AU - He, Ning
AU - Xiao, Zongyuan
AU - Xie, Youping
AU - Chang, Jo Shu
AU - Lin, Lu
AU - Lu, Yinghua
N1 - Funding Information:
This research project was financially supported by the Special Fund for Fujian Ocean High-Tech Industry Development (No. 2013015 ), China and Natural Science Foundation of China (No. 21406185 ). The authors are grateful to Dr. Ching-Nen Nathan Chen in the Institute of Marine Biology, National Sun Yat-sen University (Taiwan, ROC) for providing the microalgae strain. Theoneste Ndikubwimana gratefully acknowledges the Xiamen University, China Scholarship Council and the Government of Rwanda through Rwanda Education Board (REB) for the support. The authors are grateful to Prof. Nanfeng Zheng’s Group in the Department of Chemistry, Xiamen University for the Zeta potential assessment.
PY - 2015/9/5
Y1 - 2015/9/5
N2 - Poly-γ-glutamic acid (γ-PGA) broth was found to be a good bioflocculant of microalgae. However, the mechanism governing this bioflocculation process is not fully understood. In this study, Zeta potential measurement, microscopy examination and classical DLVO theory (named after Derjaguin, Landau, Verwey and Overbeek) analysis were used to explore the flocculability of microalgae induced by bacterial γ-PGA broth bioflocculant. Microalgae flocculation could be significantly improved by modifying ionic strength of the microalgae suspension, lowering pH value and bioflocculant addition due to the stronger attraction interactions between microalgal cells. In the present study, both the pH reduction with the bioflocculant induced better the flocculation process compared to the modification of ionic strength of the microalgae suspension in the presence of the bioflocculant. The DLVO theory indicated that when the bioflocculant was introduced, the total interaction energy decreased sharply, resulting in higher flocculation efficiency (>96 %) at a separation distance of 5. nm and shorter settling time (from 2. h to 10. min) compared with that obtained only by reducing the initial pH. The microalgae interaction energy was found to be dependent on the Zeta potential. This study provided a detailed interpretation of conceivable mechanism of microalgae bioflocculation by γ-PGA broth.
AB - Poly-γ-glutamic acid (γ-PGA) broth was found to be a good bioflocculant of microalgae. However, the mechanism governing this bioflocculation process is not fully understood. In this study, Zeta potential measurement, microscopy examination and classical DLVO theory (named after Derjaguin, Landau, Verwey and Overbeek) analysis were used to explore the flocculability of microalgae induced by bacterial γ-PGA broth bioflocculant. Microalgae flocculation could be significantly improved by modifying ionic strength of the microalgae suspension, lowering pH value and bioflocculant addition due to the stronger attraction interactions between microalgal cells. In the present study, both the pH reduction with the bioflocculant induced better the flocculation process compared to the modification of ionic strength of the microalgae suspension in the presence of the bioflocculant. The DLVO theory indicated that when the bioflocculant was introduced, the total interaction energy decreased sharply, resulting in higher flocculation efficiency (>96 %) at a separation distance of 5. nm and shorter settling time (from 2. h to 10. min) compared with that obtained only by reducing the initial pH. The microalgae interaction energy was found to be dependent on the Zeta potential. This study provided a detailed interpretation of conceivable mechanism of microalgae bioflocculation by γ-PGA broth.
UR - http://www.scopus.com/inward/record.url?scp=84930941180&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84930941180&partnerID=8YFLogxK
U2 - 10.1016/j.bej.2015.05.010
DO - 10.1016/j.bej.2015.05.010
M3 - Article
AN - SCOPUS:84930941180
SN - 1369-703X
VL - 101
SP - 160
EP - 167
JO - Biochemical Engineering Journal
JF - Biochemical Engineering Journal
ER -