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

Lee, Siah Lee and Chong, Mei Fong and Robinson, John P. and Binner, Eleanor (2015) Optimisation of extraction and sludge dewatering efficiencies of bio-flocculants extracted from Abelmoschus esculentus (okra). Journal of Environmental Management, 157 . pp. 320-325. ISSN 1095-8630

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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.

Item Type: Article
Keywords: Bio-flocculant; Optimisation; Extraction; Okra; Sludge dewatering
Schools/Departments: University of Nottingham UK Campus > Faculty of Engineering
University of Nottingham, Malaysia Campus > Faculty of Engineering > Department of Chemical and Environmental Engineering
Identification Number: https://doi.org/10.1016/j.jenvman.2015.04.028
Depositing User: Binner, Eleanor
Date Deposited: 01 Mar 2016 08:09
Last Modified: 16 Sep 2016 02:02
URI: http://eprints.nottingham.ac.uk/id/eprint/31936

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