Evaluation of banana peel hydrolysate as alternate and cheaper growth medium for growth of microalgae Chlorella sorokiniana

Continuously escalating energy demand and depletion of conventional fossil fuels has challenged and urged our globe to search for alternative resources which are economically viable, renewable and sustainable. Microalgae has emerged as an excellent resource in this regard but the excessive cost of nutrients is a vital restriction for producing economically viable algal fuels. In this study, waste banana peels were used as the feedstock for cultivation medium for microalgae after proper pre-treatment and hydrolysis. Various pre-treatment techniques were executed and the best conditions (40 min, autoclaving) furnishing the higher glucose concentration were chosen for further investigation. Rationale for the enzyme hydrolysis of the pre-treated peels was created through central composite design (CCD) using response surface methodology (RSM) to attain higher concentration of glucose to optimize the hydrolysis parameters. Temperature (degrees C), time (h) and the rotation frequency or agitation speed (revolutions per min, RPM) of the incubator were the three chosen parameters. 29.84 +/- 0.57 g L-1 glucose was obtained from the banana peels. The peel extract after hydrolysis was used as the medium for microalgal growth, and the growth kinetics of the two microalgal isolates (Chlorella sorokiniana KMBM_I and Chlorella sorokiniana KMBM_K) cultivated in the waste peel hydrolysate were evaluated. Chlorella sorokiniana KMBM_K and Chlorella sorokiniana KMBM_I displayed a biomass yield of respectively 1.72 and 1.53 g L-1 with a lipid content of 22.83% and 22.17% respectively. This study demonstrated that this organic peel waste can act as an effective, eco-friendly, efficient and natural substrate for cost effective microalgal cultivation.