Abstract

Biofuel serves as an alternative energy to the common fossil fuels currently in use globally and are drawing increasing attention worldwide as substitutes for petroleum-derived transportation fuels to help address challenges associated with petroleum derived fuels. Third generation biofuels, also termed advanced biofuels, are produced from fast growing microalgae and are potential replacements for conventional fuels. The growth and biomass production of these microalgae is dependent on the conditions they are cultivated such as pH and Salinity. Cassava waste mixtures were cultivated on Chlorella vulgaris stock culture at different concentration ratio at ambient temperature, natural light and dark conditions at 670nm absorbance for 14 days. Optimum growth was obtained at 160:40 for cassava peel water to cassava waste water CP:CW. pH variations 6.0, 6.5, 7.0, 7.5, 8.0, 8.5 and 9.0 were checked to determine the optimum pH for the growth and biomass production of Chlorella vulgaris on the optimum cassava waste mixture concentration. It revealed that at pH 6.5, optimal growth and biomass production was achieved, minimal growth was observed at pH 8.0 while minimal biomass was produced at pH 9.0. Salinity variations of 5, 10, 15, 20, 25, 30, 35 and 40 mg/l were used to determine the growth response and biomass production of Chlorella vulgaris. It revealed that salinity variation at 10ppm will be necessary for highest growth on the cassava waste as well as in biomass production. The use of optimal pH and salinity can significantly increase biomass production thus enhancing biofuel production.

Highlights

  • Nigeria is the largest producer of cassava roots being responsible for about 20% of the total cassava product contributing its quota to the expansion of world cassava production from 200 million in 2004 to 240 million in 2009 (1)

  • The pH and salinity variation on the growth and biomass production of Chlorella vulgaris on cassava waste are shown on fig. 1-8

  • The results showed that pH and salinity variations significantly affected the growth and biomass production of the microalgae

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Summary

Introduction

Nigeria is the largest producer of cassava roots being responsible for about 20% of the total cassava product contributing its quota to the expansion of world cassava production from 200 million in 2004 to 240 million in 2009 (1). Microalgae represent one-third (1/3) of the world’s plant biomass and its renewable energy potential can be more environmentally sustainable, cost effective and more profitable if combined with processes such as waste management and utilization (4). These microalgae in turn are used to produce various beneficial biochemicals used in food, aquaculture, poultry and pharmaceutical industries (5). With the increase of pH, CO2 in water is converted to HCO3-which is the mainly existing formation of carbon in weak alkaline and is majorly utilized by microalgae Salinity is another important factor that alters the biochemical composition of algal cells (salinity refers primarily to sodium chloride concentration unless otherwise specified). Microalgae have its own system to adjust salinity range and studies have shown that microalgae have its own optimal growth salinity, salinity levels which are higher or lower than the optimal level will be harmful to algal growing rate

Sample collection
Sample preparation
Experimental studies
Optical Density
Results and discussion
Conclusion
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