*Corresponding author’s e-mail: nazlinayasin@ukm.edu.my ASM Sc. J., 17, 2022 https://doi.org/10.32802/asmscj.2022.930 Growth Kinetics Determination Using Different Mathematical Models for Microalgae Characium sp. UKM1, Chlorella sp. UKM2 and Coelastrella sp. UKM4 Mohamad Faisal Ni Aznan 1 , Nazlina Haiza Mohd Yasin 1* , Norzila Mohd 2,3 and Mohd Sobri Takriff 3,4 1 School of Bioscience and Biotechnology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia ²School of Chemical Engineering, College of Engineering, Universiti Teknologi MARA, Terengganu Campus, Bukit Besi Brunch, 23200 Dungun, Terengganu 3 Department of Chemical and Process Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43000 UKM Bangi, Selangor, Malaysia 4 Chemical and Water Desalination Program, College of Engineering, University of Sharjah, Sharjah, United Arab Emirates Microalgae are extensively used in industry due to their potential in producing high-value metabolites. The good microalgae growth kinetics performance is essential owing to excellent microalgae biomass harvesting efficiency. Therefore, the best mathematical model for the growth kinetics of microalgae is required to predict the correct growth kinetics value and helps in the elucidation of downstream processes. This study embarks on the objective to determine the best mathematical models for three local microalgae which are Characium sp. UKM1, Chlorella sp. UKM2 and Coelastrella sp. UKM4 cultured in Bold Basal Media (BBM). The four mathematical models are used to evaluate the growth kinetics of microalgae which include logistic model (Lm), modified logistic model (MLm), modified Gompertz model (MGm) and Baranyi-Roberts model (BRm). The experimental data were compared to the predicted data through the residual plot. The comparison shows that BRm is the best model to fit UKM1, UKM2 and UKM4 due to the experimental data which is close to the x-axis of the residual plot indicating the data were fitted the best to the BRm. The statistical analysis confirmed that all microalgae growth patterns exhibited that the BRm is the best model owing to the lowest percentage of standard error prediction indicating the lowest error compared to the other models. In addition, accuracy and bias factors are near to one which assess the precision of these models. In conclusion, the growth of UKM1, UKM2 and UKM4 grown in BBM is best fitted to the Baranyi-Roberts model. Keywords: Microalgae; Characium sp. UKM1; Chlorella sp. UKM2; Coelastrella sp. UKM4; mathematical model I. INTRODUCTION Microalgae are widely used in wastewater treatment, CO₂ sequestration and the metabolites produced in microalgae are often used to produce third-generation biofuel. Microalgae can grow in a robust condition with faster growth rates compared to terrestrial plants. Nevertheless, high-value microalgae-based products are interesting insights for commercialisation (Japar, Takriff & Mohd Yasin, 2021). In order to enhance the product accumulation in microalgae biomass, the growth of microalgae is an