Biodiesel production by microalgal species isolated from water samples in Keffi, Nasarawa state, Nigeria

Abstract

To counter the effects of climate change due to use of fossil fuels, much attention has been placed into the production of biomass-derived fuels. This investigation was aimed at producing biodiesel from microalgae species isolated from water samples in Keffi, Nasarawa state. Standard microbiological methods were used for isolation and identification of the microalgal isolates. The percentage occurrence of the isolates showed that Chlorella vulgaris had a 100% occurrence with Chlorella lewinii and Stigeoclonium tenue having a 50% occurrence each while Cladophora glomerata having a 25% occurrence. The growth curve showed that the micro algal isolates experienced exponential growth under daily sunlight exposure. The effect of temperature on the biomass and lipid extracted showed that Chlorella vulgaris, Chlorella lewinii and Stigeoclonium tenue had the highest biomass yields of 8.01g/l, 12.17 g/l and 15.10 g/l respectively and lipid production of 3.30 µg/l, 3.11 µg/l and 5.11 µg/l respectively at 32 ℃. Further increase in temperature led to decrease in their biomass yields and lipid production. The effects of pH showed that all the microalgal isolates had its highest biomass yields and lipid production in an alkaline pH of 7.5 but when the pH was reduced up to 4.5, the resultant microalgal biomass yields and lipid production of the microalgal isolates decreased. The fatty acid profiles of the biodiesel derived from the microalgal isolates showed that it was composed mainly of palmitic, oleic, Myristic and Stearic acids which made it a viable fuel source.