ABSTRACT
Aims@#Microalgae were very small in size (a few μm) and have a low concentration in the medium. Due to their size, harvesting of microalgae from their growth medium remain a major obstacle in downstream processing. Efficient harvesting method must be applied to ensure it is cost effective, preserves quality and improves the culture process which is important for commercial algal production. Common harvesting methods use to harvest microalgae from their growth medium are centrifugation, filtration, flotation, sedimentation, and flocculation. Flocculation is a common method use to harvest microalgae due to low cost, save time and highly efficient method for algae biomass recovery. The purpose of this study was to investigate the effects chitosan and eggshell on flocculation of microalga Spirulina platensis. Chitosan and eggshell were chosen as flocculant due to their biodegradability, non-toxicity and safe to handle. @*Methodology and results@#The efficiencies of flocculation process were examined by conducting experiments over a range of culture pH, flocculant concentrations and flocculation time using chitosan and eggshell as flocculant agent. Under optimized flocculation conditions of 50 mg/L chitosan at pH 8 culture media for 90 min of flocculation time and 4 mg/mL eggshell at pH 4 culture media for 8 min of flocculation time, the maximum flocculation efficiency obtained was 79.98±1.65% and 97.17±1.38%, respectively. @*Conclusion, significance and impact of study@#Therefore, it can be concluded that chitosan and eggshell could be used as flocculants for harvesting large scale microalgal biomass production. Nevertheless, eggshell is more economical and more efficient compared to chitosan in harvesting microalgae biomass.
ABSTRACT
@#Aims:In this study, ten indigenous microalgae samples from freshwater and marine waters from Malaysia, cultured and analysed on proximate and biochemical analysis. The proximate and biochemical analysis consists of starch, carbohydrates, lipid, protein, ash and moisture contents. This study was more focused on screening of starch accumulation in marine and freshwater microalgae cultures. Methodology and results:Based on screening, the results showed that Chlorella salinacontents highest starch of 4.92±0.33%, followed by Spirulinasp. 2.58±1.18%, Isochrysis maritime 0.99±0.33%, and lastly for Nitzschiapanduriformisand Naviculadistanscontents similar percentage of starch (0.44±0.10 and 0.40±0.07%, respectively). Besides starch analysis, proximate analyses(ash, moisture, lipid, protein, and carbohydrates) have been conducted. The results obtained indicated that all the cultures contain more than 4.50% of carbohydrates in average, followed by lipid and protein <1%. The results demonstrate that further optimization and various harvesting stages (early of exponential phase, early of stationary phaseand late stationary phase) may increase lipid, carbohydrates, starch, and protein accumulation. Chlorella salinaand Spirulinasp. will be used to further study on optimization of physical and chemical factors for high starch accumulation. Conclusion, significance and impact of study:In conclusion, this experiment focused more on preliminary screening for further application of starch uses in food and food packaging indust