A synergic approach for nutrient recovery and biodiesel production by the cultivation of microalga species in the fertilizer plant wastewater

Indu Ambat,Sabina Bec,Mika Sillanpää,Varsha Srivastava,Anne Ojala,Elina Peltomaa

doi:10.1038/s41598-019-55748-w

Indu Ambat, Sabina Bec + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-55748-w

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Abstract

The combination of wastewater treatment and biodiesel production using algal cultivation was studied in the present work. The two main goals of the work were achieved by the cultivation of freshwater microalgae such as Chlamydomonas sp., Scenedesmus ecornis, and Scenedesmus communis in two different dilutions of fertilizer plant wastewater (FWWD1 and FWWD2) collected from Yara Suomi Oy, Finland. The growth pattern of different algal species in FWWD1 and FWWD2 was observed. The effect of pH on biomass concentration, lipid content, biomass productivity, and lipid productivity by all three algal species in FWWD1 and FWWD2 were monitored. The maximum biomass concentration and productivity were observed in FWWD1 at pH7.5 for Chlamydomonas sp. and at pH 8.5 for S. ecornis and S. communis. The maximum lipid content was detected in Chlamydomonas sp at pH5.5, followed by S. ecornis and then S. communis at pH 7.5 in FWWD2 obtained after co-solvent extraction method. The most significant removal percentage of COD by all algal species were observed in FWWD1, whereas the highest removal percentage of TN and TP were detected in FWWD2, respectively. The fatty acid methyl ester (FAME) characterization of each algal species in FWWD1 and FWWD2 at their optimum pH was investigated to determine the quality of obtained biodiesel.

Highlights

The combination of wastewater treatment and biodiesel production using algal cultivation was studied in the present work
The total phosphorus (TP), chemical oxygen demand (COD), total nitrogen (TN), and pH of wastewater samples were monitored before algal cultivation
The results indicated that there were significant (P < 0.05) differences between the dilutions (FWWD1 and FWWD2) and pH used for cultivation for different algal species

Summary

Introduction

The combination of wastewater treatment and biodiesel production using algal cultivation was studied in the present work. The maximum lipid content was detected in Chlamydomonas sp at pH5.5, followed by S. ecornis and S. communis at pH 7.5 in FWWD2 obtained after co-solvent extraction method. The scarcity of conventional fuels and pollution of water resources have been a global issue with the population growth[1,2] It leads to the need for sustainable alternative fuels and reusing of wastewater using different treatment technologies[2,3]. Biodiesel derived from algal biomass grown in wastewater medium serves as a promising sustainable, eco-friendly, and cost-efficient source of energy[2,12,14,16,19,20,21]. In 2010 methanol was stated as right choice as polar covalent molecules (PCM) for lipid extraction by Young et al and in 2014, 1-ethyl-3-methyl imidazolium diethyl phosphate, [Emim] DEP reported as a best ionic liquid by Choi et al.[21,25]

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