Study on the effect of nutrient on microalgae growth profile and extracellular polymeric substance excretion
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Date
2019-06
Authors
Siti Najeeha Binti Sheikh Abdullah
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Abstract
Microalgae shows a great potential in biological wastewater treatment as well as biofuel production. This is due to microalgae’s capability in consuming excess nutrients and production of lipid from the biomass. Despite many advancements in this era, many challenges restrain the commercialisation of microalgae for biofuel production. This is due to the technology in harvesting and separation of microalgae is costly. In this study, the effect of nutrient availability on the growth profile and extracellular polymeric substance (EPS) excretion by microalgae were investigated. Two reactors were set up for investigations in which Reactor 1 (R1) (control reactor) and Reactor 2 (R2) (nitrogen starved), samples from both reactors were collected at prefixed interval for mixed liquor suspended solid (MLSS), mixed liquor volatile suspended solid (MLVSS), nutrient analysis and EPS content analysis. In this investigations, microalgae in R1 and R2 exhibit lag phase, exponential phase and stationary phase. Although, R2 were subjected with starvation period, the maximum concentration of its microalgae and the growth profile shows similar trend as R1. The EPS production in both reactors increases over time. However, the EPS content during nitrogen shortage in R2 was found decreases. This might be explained by the directly proportional correlations of EPS excretion to the nutrient availability. Composition of EPS such as protein and carbohydrate was analysed for further understanding and correlation. Protein was found as the major component of EPS in both reactors. Carbohydrate content of EPS was found low in both reactors and it might be consumed by microalgae as energy source.