Domestic Wastewater Treatment and Lipid Accumulation for Biodiesel Production by an Isolated Heterotrophic Microalgae from an Arid Climate Zone

Abstract

The isolation of microalgae that can use carbon-rich pollutant from wastewater and accumulate lipids is of great interest in biodiesel production. The heterotrophic cultivation of microalgae could overcome light dependency, and hence increase the yield of microalgae lipid per unit area. After several microbial screening and acclimation procedures, strains of microalgae were proved to be tolerant of wastewater and to grow heterotrophically. One top-performing strain (AE2) was identified through morphological observation as Chlorella sp and was isolated from an open pond of domestic wastewater. This microalgae is able to grow in raw wastewater at 20°C with no illumination and eliminates 100% of its COD (424 mg/L) in 9 days. The biomass produced in wastewater as growth medium comprises 53% of fats of the dry mass and 68% of fats of the dry mass in BG 11 culture medium supplemented with 5 g of glucose/L. The analysis of fatty acid methyl esters FAME composition was 32.5 % of the total biomass. The extracted microalgae oil was converted to good quality biodiesel. This heterotrophic isolated microalgae is a promising strain in terms of wastewater COD removal and cytoplasmic accumulation of high quality and quantity lipids for prospective biodiesel production. Contribution/Originality:This study is one of the very few studies which have investigated the isolation of microalgae from the southern climate that can grow efficiently in low carbon sources such as wastewater. The isolated microalgae produced biomass with 53% of fats that are favorable in term quantity and quality for biodiesel conversion.

Microalgae-based wastewater treatment: Mechanisms, challenges, recent advances, and future prospects

“…To date, a wide range of microalgae has been reported to treat domestic WW, such as Scenedesmus abundans, Botryococcus sp ., Chlorella variabilis, Chlorella sp ., Scenedesmus sp. , Scenedesmus obliquus, Chlorella vulgaris, and Chlorella sorokiniana , as depicted in Table 1 [ [42] , [43] , [44] , [45] , [46] , [47] , [48] ].…”

“… Microalgae Waste source Biomass production Reference Chlorella variabilis Domestic wastewater 1.72 g L −1 [ 42 ] Scenedesmus abundans Domestic wastewater 3.55 g L −1 [ 43 ] Scenedesmus obliquus Municipal wastewater 0.22 g L −1 d −1 [ 44 ] Chlorella sp. Domestic wastewater 0.73–1.38 mg L −1 d −1 [ 45 ] Scenedesmus sp. Municipal wastewater 1.81 g L −1 [ 46 ] Scenedesmus sp.…”