Microalgae has long been a widely commercialized. Microalgae are known for their role in generating energy such as biofuels and biodiesel. Microalgae also play a role in animal and fish food supplements. Besides having good nutritional value, microalgae are a natural source of pigments, antioxidants, and other bioactive compounds with functional properties. So do not be surprised if the metabolites or the metabolism of microalgae are sought after as high-value products.
These microorganisms also have faster growth rates, produce more biochemical compounds, and have significant results in bioremediation to reduce the amount of pollutants in wastewater.
Waste water treatment with microalgae offers several advantages, such as lower cost and the environmentally friendly process of removing nutrients in waste and the production of biomass. Because of this, many researchers are looking for ways to influence the ability of metabolism, tolerance, and survival of microalgae in the environment.
Several studies have shown that the effect of acidity (pH) and light intensity or photoperiod is very high on algal growth and production. This factor also has an impact on algal protein and carbohydrate levels.
A follow-up study was conducted to determine the utilization of the Scenedesmus sp. in identifying growth rates and biomass productivity. Also, to determine the optimal bioremediation conditions that might be carried out in the future when these microalgae are exposed to wastewater and biomass production.
In this study, microalgae Scenedesmus sp. were taken and isolated from freshwater pools in Endau Rompin National Park, Johor, Malaysia. Subcultures were performed on microalgae cells isolated in Bold Basal Media (BBM). The isolated microalgae cells are transferred to BBM. Then, BBM is placed in the sun as a source of light for 12 days before the experiment is carried out. In this experiment, microalgae cell culture was conditioned with different pH and light intensity.
This study showed that microalgae were sensitive to pH changes and influenced pH condition greatly. Scenedesmus sp. known to be more productive at pH 7 and pH 8 with the highest biomass productivity at pH 7.5.
Microalgae can still grow well in pH 9 environments that tend to be alkaline. As mentioned earlier, microalgae are sensitive to changes in pH and growth tends to increase in environments with high pH. This is due to the ability of microalgae to process inorganic carbon.
However, the pH range of 7 and 8 is very crucial so that Scenedesmus sp. can grow effectively and have a big impact on algal growth rates and biomass production.
Photoperiod also contributes to the growth of Scenedesmus sp. In this study, there are five photoperiod conditions, namely 24 hours of light: 0 hours of darkness, 16 hours of light: 8 hours of darkness, 12 hours of light: 12 hours of darkness, 6 hours of light: 18 hours of darkness, and 0 hours of light: 24 hours of darkness.
The highest microalgae growth was obtained when microalgae were exposed to photoperiod 18: 6, which produced the highest biomass production of 73.9 × 10 4 cells / mL / day and a growth rate of 0.75 days -1 .
However, photoperiod 12: 2 and 24: 0 can also be considered efficient because the growth rate of microalgae is in line with the growth of microalgae exposed to photoperiode 18: 6. This is caused by the important role of light in photosynthesis for cell growth. So in the light phase, microalgae photosynthesize and produce and change energy, while in the dark phase, there is no photosynthetic reaction. Photoperiods also affect the algal cell nitration value and chemical composition.
From this study, it can be concluded that there is an increase in growth and productivity of Scenedesmus sp. at different pH and photoperiods. The best pH for microalgae growth and biomass production is alkaline, more precisely the pH range 7-8. Meanwhile, the best photoperiods are 18: 6 and 12: 2.
It also proved that Scenedesmus sp. can be used for wastewater treatment in natural conditions and it can increase biomass production by conditioning the pH and photoperiod. (*)
Details of this research available at