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Evaluation of microalgae as bioremediation agent of olive mill wastewater
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1  Chemistry Center - Vila Real, CQVR, Chemistry Department, University of Trás-os-Montes and Alto Douro, Quinta de Prados 5000-801, Vila Real, Portugal
Academic Editor: Simeone Chianese


Olive oil industry is an important sector within the agro-food industries in the Mediterranean countries but constitutes a major environmental problem regarding the disposal of its wastewaters. Olive mill wastewater (OMW) is a turbid, dark colored, foul-smelling and acidic effluent. It presents a low biodegradability due to its antibacterial activity, given by the phenolic content1. Bioremediation through microalgae is an interesting option, since it is an environmentally friendly process, as wastewaters can be used as cheap nutrient sources for microalgal biomass production that could be a source of stored chemical bond energy, especially into lipids, carbohydrates and proteins2. The main objective of this work was to evaluate the potential for bioremediation of two OMW with different origin - olives washing (OW-OMW) and olive oil extraction (OMW) - by microalgae. It were used three species of green microalgae, Chlorella vulgaris, Chlorella protothecoides and Scenedesmus obliquus and the cyanobacterium Arthrospira maxima. Due to the complexity of the effluents, it was necessary a dilution of media: 5% for OMW and 50% for OW-OMW. The best removals of chemical oxygen demand (COD) removal were 61.6% for OMW and 67.9% for OW-OMW in cultures of C. protothecoides and C. vulgaris, respectively. Significant removals of phosphorus (P-PO4) were only verified with Arthrospira (67.0% for OMW and 36.0% for washing wastewater). Regarding nitrates (N-NO3), very satisfactory removal rates were obtained with all microalgae (around 80 %). Due to difficult biological degradation, the removal of polyphenols did not exceed 40 % for both OMWs. Although microalgae can grow in these OMWs and show potential for its bioremediation, further studies will not be feasible if this effluent is not subjected to a primary treatment, since its toxicity causes cellular death after 4 days.


Authors acknowledge the OBTain project (NORTE-01-0145-FEDER-000084), co-financed by the European Regional Development Fund (ERDF) through NORTE 2020, and FCT for the financial support to CQVR (UIDB/00616/2020).


  1. Amor, C., Marchão, L., Lucas, M. S. & Peres, J. A. Application of Advanced Oxidation Processes for the Treatment of Recalcitrant Agro-Industrial Wastewater: A Review. Water 11, 205 (2019).
  2. Marchão, L. et al. Microalgae and immobilized TiO2/UV-A LEDs as a sustainable alternative for winery wastewater treatment. Water Res. 203, 117464 (2021).
Keywords: Arthrospira maxima, Bioremediation, Chlorella vulgaris, Chlorella protothecoides, Scenedesmus obliquus, Olive mill wastewater.
Comments on this paper
Nuno Filipe Alves Jorge
Excellent paper.

Congratulations :)