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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 538106
Title Natural flocculants from fresh and saline wastewater : Comparative properties and flocculation performances
Author(s) Ajao, Victor; Bruning, Harry; Rijnaarts, Huub; Temmink, Hardy
Source Chemical Engineering Journal 349 (2018). - ISSN 1385-8947 - p. 622 - 632.
Department(s) Sub-department of Environmental Technology
Publication type Refereed Article in a scientific journal
Publication year 2018
Keyword(s) Bioflocculant - Extracellular polymeric substances - Industrial wastewater - Mixed culture - Natural polyelectrolyte - Resource recovery

Natural flocculants, due to their eco-friendliness, have gained increasing attention for (waste) water treatment and are promising alternatives to oil-based synthetic flocculants. We systematically investigated simultaneous industrial wastewater treatment with the production of microbial extracellular polymeric substances (EPS) as natural flocculants. EPS were produced in two membrane bioreactors, respectively treating fresh and saline synthetic wastewater from biodiesel and (bio)ethanol industries. From each reactor, soluble and bound EPS fractions were extracted, purified and characterised for their functionalities, molecular weights and charge densities using Fourier transform infrared (FTIR), size exclusion chromatography and colloid titration, respectively. High removal of chemical oxygen demand (COD) was achieved in both reactors (93–95%), with 5.8–7.6% of the inlet COD recovered as EPS. FTIR spectroscopy reveals these EPS as a mixture of proteins and polysaccharides, possessing carboxyl, hydroxyl and amine groups. These functional groups, which provided a net anionic charge density (1.5–2.9 meq/g at neutral pH), coupled with EPS mixed molecular weight (MW) distribution: high (>1000 kDa), medium (1000–100 kDa) and low (<100 kDa) MW fractions, make them promising flocculants. Extracted EPS showed good flocculation of non-saline kaolin suspension (74–89% turbidity reduction) and excellent flocculation of saline kaolin suspension (88–97%), performances comparable to anionic polyacrylamide. The results show the possibility for wastewater treatment plants to combine wastewater treatment with the production of valuable flocculants.

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