Cultivation of Chlorella minutissima under a novel phosphate application strategy for biodiesel production: A pilot scale study

Abstract

Microalgal biodiesel is considered as a carbon-neutral and renewable energy source for replacing/blending with petroleum-based diesel fuel. Selection of a microalgal species for its potential to produce biodiesel relies significantly on its acclimatization to grow in outdoor condition with high lipid productivity. The present investigation undertakes outdoor experiments in a raceway pond system involving a local isolate of green microalga, Chlorella minutissima, throughout varied seasonal changes and culture depth. The variations in climatic and cultural parameters were documented; the optimum culture depth of 30 cm was taken for further investigation. A novel cultivation approach incorporating the sequential addition of low-dose phosphate (LDSPA) projected a lipid productivity of 5.88 ton hectare−1 year−1, which was ∼40% higher than its batch culture counterpart, along with a 14-fold reduction in phosphate application. The biodiesel exhibited the dominance of saturated and monounsaturated fatty acid methyl esters, and the fuel qualities were confirmed to be within the stipulated limitations of European, American and Indian biodiesel standards, thus nominating C. minutissima as an attractive feedstock for generating high-quality biodiesel.