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Water 2018, 10(8), 977; https://doi.org/10.3390/w10080977

Evaluation of Pre-Chlorinated Wastewater Effluent for Microalgal Cultivation and Biodiesel Production

1
Discipline of Microbiology, School of Life Sciences, College of Agriculture, Engineering and Science, University of KwaZulu-Natal (Westville Campus), Private Bag X54001, Durban 4041, South Africa
2
Centre for Algal Biotechnology, Department of Nature Conservation, Mangosuthu University of Technology, P.O. Box 12363, Jacobs, Durban 4026, South Africa
3
Laboratory of Biosystems Engineering, Institute of Biotechnology, Jiangsu Academy of Agricultural Sciences, Nanjing 210014, China
*
Author to whom correspondence should be addressed.
Received: 4 June 2018 / Revised: 2 July 2018 / Accepted: 7 July 2018 / Published: 25 July 2018
(This article belongs to the Section Water–Food–Energy Nexus)
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Abstract

Microalgae are promising feedstock to produce biodiesel and other value added products. However, the water footprint for producing microalgal biodiesel is enormous and would put a strain on the water resources of water stressed countries like South Africa if freshwater is used without recycling. This study evaluates the utilization of pre-chlorinated wastewater as a cheap growth media for microalgal biomass propagation with the aim of producing biodiesel whilst simultaneously remediating the wastewater. Wastewater was collected from two wastewater treatment plants (WWTPs) in Durban, inoculated with Neochloris aquatica and Asterarcys quadricellulare and the growth kinetics monitored for a period of 8 days. The physicochemical parameters; including chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were determined before microalgal cultivation and after harvesting. Total lipids were quantified gravimetrically after extraction by hexane/isopropanol (3:2 v/v). Biodiesel was produced by transesterification and characterised by gas chromatography. The total carbohydrate was extracted by acid hydrolysis and quantified by spectrophotometric method based on aldehyde functional group derivatization. Asterarcys quadricellulare utilized the wastewater for growth and reduced the COD of the wastewater effluent from the Umbilo WWTP by 12.4%. Total nitrogen (TN) and phosphorus (TP) were reduced by 48% and 50% respectively by Asterarcys quadricellulare cultivated in sterile wastewater while, Neochloris reduced the TP by 37% and TN by 29%. Although the highest biomass yield (460 mg dry weight) was obtained for Asterarcys, the highest amount of lipid (14.85 ± 1.63 mg L−1) and carbohydrate (14.84 ± 0.1 mg L−1) content were recorded in Neochloris aquatica. The dominant fatty acids in the microalgae were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). The biodiesel produced was determined to be of good quality with high oxidation stability and low viscosity, and conformed to the American society for testing and materials (ASTM) guidelines. View Full-Text
Keywords: wastewater; wastewater treatment plant; microalgae; biodiesel; effluent wastewater; wastewater treatment plant; microalgae; biodiesel; effluent
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Odjadjare, E.C.; Mutanda, T.; Chen, Y.-F.; Olaniran, A.O. Evaluation of Pre-Chlorinated Wastewater Effluent for Microalgal Cultivation and Biodiesel Production. Water 2018, 10, 977.

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