Effect of operating conditions on Chlorococcum sp. growth and lipid production

Abstract

Microalgal cultivation has attracted global attention in recent years. It is a worldwide rapidly growing business sector due to the numerous applications of microalgae biomass and the valuable natural by-products. Some of these products are used in pharmaceutical, biomedical, cosmetic, and food industries, and recently in biofuel production. The cost reduction of microalgal biomass production is an essential factor, and many studies have been focused on microalgae cultivation in wastewater. The selection of microalgae for biomass and lipid production is a very crucial factor. Chlorococcum sp. are common microalgae, found in wastewater. The aim of this study was to investigate the effect of initial biomass concentration, air supply, and type and duration of light exposure of Chlorococcum sp. cultures in a high nutrient concentration synthetic wastewater. Experiments were conducted under controlled environmental conditions in order to investigate the removal of nutrients from wastewater, the biomass growth rates, and lipids accumulation in microalgae. The results of this study demonstrated that high initial biomass concentration is more efficient for lipid production. Specifically, higher lipids content (27.7%) was observed with high initial microalgae concentration, even though the phosphorus concentration was almost zero. Biomass production was increased faster at the higher air flow rate (6L/min), without need for addition of carbon dioxide (CO2). Τhe growth rate of Chlorococcum sp. was greater under artificial light compared to sunlight exposure, as well as the CO2 biofixation, since it is directly related to the algal biomass.