Chapter 12 - Bioconversion of Agricultural Wastes From the Livestock Industry for Biofuel and Feed Production

Abstract

The bioconversion of sunlight energy into biofuels can be coupled to nutrient recovery from organic wastes using systems that employ microalgae grown symbiotically with heterotrophic microorganisms. Of interest for algae biofuel production is the high amounts of oil (lipid) produced, primarily as triglycerides. A major cost factor for algal biomass production is the provision of water and nutrients. In this chapter, progress made in microalgae-based systems using primary manure effluents with high biological oxygen demand levels that microbes decompose into inorganic nutrients including CO2, ammonium, and phosphate is reviewed. Anaerobic digesters offer an attractive alternative to direct treatment of agricultural wastes with several advantages from a fuel production perspective. During anaerobic digestion, organic matter is mineralized producing methane for fuel and inorganic C, N, and P, nutrients needed for algal growth. In each case, a resource and economic synergy are possible as algae-based bioremediation generates revenue from the treatment service and improves the economics of biofuel production.