Increasing lipid content from biomass of microalgae to produce biofuels with optimization of nitrogen source

Universitas Trisakti, Environmental Engineering Departement, Faculty of Landscape Architecture and Environmental Technology, Jakarta, Indonesia

^* Corresponding author: melati@trisakti.ac.id

Abstract

The aim of this research is to analyze the effect of urea fertilizer as a nitrogen source to lipid productivity of mixed culture of green microalgae consisting of Monoraphidium sp., Chlorella sorokiniana, and Scenedesmus obliquus as lipid sources. In research, cultures were cultivated in a 1.5 L glass photobioreactor with batch culture system. The operational conditions of this research were carried out at pH 6.0, 27 °C, aeration with air flow 150 mL/sec, and 2400 lux with vary amount of urea as a source of nitrogen as much (grams) 0.0; 0.5; 1.0. The Bligh and Dyer extraction is performed to produce biofuels after harvesting process and to analyze lipid content. Analysis of fatty acids using Gas Chromatography Mass Spectrometry (GCMS) Method, analysis of dry weight using Gravimetric Method, and analysis of cell density using Spectrofotometry Method. This research concludes that with 0.5 grams of urea fertilizer can produce dry weight and total lipid content optimally that were 0.26% (w/w) and 36,35% (w/w). This research concludes that increasing amount of nitrogen source could be increasing green microalgae biomass but is not for increased lipid content. The high lipid content can be produced by decreasing 50% nitrogen source.