Coupling wastewater treatment, biomass, lipids, and biodiesel production of some green microalgae

Abstract

This study demonstrates the combination of wastewater treatment and green microalgae cultivation for the low-cost production of lipids as a feedstock for biodiesel production. Three green microalgal species were used: Chlamydomonas reinhardtii, Monoraphidium braunii, and Scenedesmus obliquus. Nutrient, heavy metals and minerals removal, biomass productivity, carbohydrate, protein, proline, lipid, and fatty acids methyl ester (FAMEs) contents besides biodiesel properties were evaluated. The results showed that all algal species were highly efficient and had the potential to reduce nitrate, ammonia, phosphate, sulfate, heavy metals (Zn2+, Cu2+, Mn2+, and Fe2+), calcium, magnesium, sodium, and potassium after 10 days of algal treatment compared to initial concentrations. The removal efficiency of these parameters ranged from 12 to 100%. The growth rates of M. braunii and S. obliquus cultivated in wastewater were significantly decreased compared to the control (synthetic medium). In contrast, C. reinhardtii showed the highest growth rate when cultivated in sewage water. Wastewater could decrease the soluble carbohydrates and protein content in all tested algae and increase the proline content in M. braunii and S. obliquus. In wastewater culture, M. braunii had the highest lipid productivity of 5.26 mg L−1 day−1. The fatty acid profiles of two studied species (C. reinhardtii and M. braunii) revealed their suitability as a feedstock for biodiesel production due to their high content of saturated fatty acids, representing 80.91% and 68.62% of the total fatty acid content, respectively, when cultivated in wastewater. This study indicated that wastewater could be used to modify biomass productivity, lipid productivity, and the quantity of individual fatty acids in some algae that affect biodiesel quality to achieve international biodiesel standards.

Bibliometric analysis of wastewater treatment with microalgae in the period 1985–2023

“…In this regard, Atif et al (2023) pointed out that microalgae use various biochemical processes to remove chemicals and nutrients such as nitrogen and phosphorus from the W to produce biomass. El-Sheekh et al (2023) pointed out that microalgae bioengineering should be aimed at increasing lipid production and fatty acid accumulation, in order to meet energy demand through the use of microalgae as feedstock in the production of third-generation biofuels. On the other hand, Atif et al (2023) mentioned that future research would be directed to the study of parameters such as temperature, biomass production, osmotic capacity, pH and O 2 levels in the efficiency of WTwM to determine optimal culture conditions on a large scale and within an industrial environment.…”

Simultaneous Phycoremediation and Lipid Production by Microalgae Grown in Non-Sterilized and Sterilized Anaerobically Digested Brewery Effluent

“…In particular, the use of food by-products and wastes such as brewery by-products and spent osmotic solutions as growth mediums can reduce operational costs by an average of 35% compared to standard cultivation methods [17]. Therefore, the use of anaerobically digested effluent as a production medium can be used to purify wastewater and produce biomass, which is rich in lipids, carbohydrates, proteins, and pigments that are used for different applications, including biofuel production [18,19].…”