University of Antwerp
Production of polyhydroxyalkanoates from industrial phenolic effluent
Focus area / active in:
- Bioprocesses & technologies
- phenolic effluents
- waste stream valorisation
Phenolic compounds are pollutants with high toxicity, even in very low concentrations. The toxicity ranges between 9 and 25 mg/L for both humans and aquatic life. Phenolic effluents stem from different branches of the industry, i.e. biorefineries, wood pulp industry, oil refineries, and chemical industry. Current physicochemical removal techniques require high amounts of chemicals or energy. Biological treatment is much more environmentally friendly, although the streams might have to be diluted first . Polyhydroxyalkanoates (PHAs) are very promising biodegradable bioplastics that are produced by microorganisms. The use of a single, specialised strain that degrades phenolic compounds and accumulates PHAs is expected to allow high yields, good process control, and high product purity. Using phenolic effluents will provide a cheap carbon source for the production of PHAs, whose cost is over 50% determined by the raw material. At the same time, the toxic phenolics will be removed from the wastewater. The sensitivity of a specialised PHA-producing and phenolic degrading microorganism, Pseudomonas putida KT2440, to the selected individual phenolic compounds was evaluated. The growth was unaffected until a concentration of 0.5 g/L phenol, o-cresol and m-cresol, of 0.25 g/L p-cresol, and, at least, 3.5 g/L furfural, 0.100 g/L 2-chlorophenol and 2,4,6-trichlorophenol and 0.27 g/L 2-nitrophenol (higher concentrations were not evaluated). Based on the literature, these values were higher than expected . In all experiments, PHA was accumulated and was measured qualitatively. Out of the evaluated components, furfural led to the highest PHA accumulation. Within 48 h, all phenolic compounds were, at least partially, removed from the wastewater, with the degradation percentages being dependent on the phenol concentration. The results show great potential for the valorisation of phenolic effluents to PHA, at the same time detoxifying highly toxic effluents. This process fits perfectly in the ever more important concept of a circular economy. In the industry of the future, every compound has value.
 S. J. Kulkarni and J. P. Kaware, Review on research for removal of phenol from wastewater, International Journal of Scientific and Research Publications, 3(4), 1-5, 2013.
 C. Liu, D. Yong, D. Yu, and S. Dong, Cell-based biosensor for measurement of phenol and nitrophenols toxicity, Talanta, 84(3), 766-70, 2011.
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