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Optimisation of extraction and sludge dewatering efficiencies of bio-flocculants extracted from Abelmoschus esculentus (okra)

Lee, Siah Lee; Chong, Mei Fong; Robinson, John P.; Binner, Eleanor

Authors

Siah Lee Lee

Mei Fong Chong



Abstract

The production of natural biopolymers as flocculants for water treatment is highly desirable due to their inherent low toxicity and low environmental footprint. In this study, bio-flocculants were extracted from Hibiscus/Abelmoschus esculentus (okra) by using a water extraction method, and the extract yield and its performance in sludge dewatering were evaluated. Single factor experimental design was employed to obtain the optimum conditions for extraction temperature (25–90 °C), time (0.25–5 h), solvent loading (0.5–5 w/w) and agitation speed (0–225 rpm). Results showed that extraction yield was affected non-linearly by all experimental variables, whilst the sludge dewatering ability was only influenced by the temperature of the extraction process. The optimum extraction conditions were obtained at 70 °C, 2 h, solvent loading of 2.5 w/w and agitation at 200 rpm. Under the optimal conditions, the extract yield was 2.38%, which is comparable to the extraction of other polysaccharides (0.69–3.66%). The bio-flocculants displayed >98% removal of suspended solids and 68% water recovery during sludge dewatering, and were shown to be comparable with commercial polyacrylamide flocculants. This work shows that bio-flocculants could offer a feasible alternative to synthetic flocculants for water treatment and sludge dewatering applications, and can be extracted using only water as a solvent, minimising the environmental footprint of the extraction process.

Journal Article Type Article
Publication Date Jul 1, 2015
Journal Journal of Environmental Management
Print ISSN 0301-4797
Electronic ISSN 1095-8630
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 157
APA6 Citation Lee, S. L., Chong, M. F., Robinson, J. P., & Binner, E. (2015). Optimisation of extraction and sludge dewatering efficiencies of bio-flocculants extracted from Abelmoschus esculentus (okra). Journal of Environmental Management, 157, https://doi.org/10.1016/j.jenvman.2015.04.028
DOI https://doi.org/10.1016/j.jenvman.2015.04.028
Keywords Bio-flocculant; Optimisation; Extraction; Okra; Sludge dewatering
Publisher URL http://www.sciencedirect.com/science/article/pii/S0301479715300311
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nc-nd/4.0





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