Shaping Sustainable Bioplastics: Illuminating Chlorella sp. Growth with Light Variations and NPK Levels

Abstract

This study delved into the exploration of a biodegradable alternative to synthetic plastics through the production of biodegradable bioplastics derived from microalgae. The investigation suggests that utilizing Chlorella sp. as a viable source for sustainable biomass in bioplastic creation holds promise due to the convenience of microalgae cultivation and its rapid growth rate. However, the large-scale cultivation of microalgae requires a considerable amount of nutrients, posing challenges to its economic viability. To address this hurdle, it becomes imperative to prioritize the enhancement of growth parameters for microalgae development. This study endeavors to identify the optimal NPK (nitrogen, phosphorus, and potassium) concentration and light spectrum for Chlorella sp. using a cost-effective NPK fertilizer medium. Various combinations of light spectra and NPK levels were examined to optimize growth conditions. Cultures of Chlorella sp. were subjected to red (660 nm), blue (460 nm), and white light (380 ~ 760 nm) which acted as experimental control over a span of 10 days. Among these, blue light yielded the highest optical density at 0.687, while red light exhibited the lowest optical density at 0.349. The findings underscore that the quantity of NPK fertilizer employed as a growth medium correlate directly with the observed cellular growth in Chlorella sp. cultures. The study also encompassed tensile strength and biodegradability assessments to characterize the resulting bioplastics. Tensile tests disclosed that bioplastics synthesized with sorbitol displayed a lower tensile strength of 0.106 MPa, in contrast to bioplastics containing both sorbitol and chitosan, which demonstrated a tensile strength of 0.167 MPa. In conclusion, both the appropriate light wavelengths and NPK nutrients emerge as pivotal factors influencing photosynthesis and the growth of photoautotrophic microalgae. The overarching objective of this research was achieved by successfully producing bioplastics using microalgae biomass residue cultivated under optimized parameters.