Phototrophic Biofuel Production From Agricultural Waste

EPA Grant Number: FP917361
Title: Phototrophic Biofuel Production From Agricultural Waste
Investigators: Prior, Maxine L
Institution: University of Idaho
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2011 through August 31, 2013
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2011) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Science & Technology for Sustainability: Green Energy/Natural Resources Production & Use


Agricultural waste streams are rich in carbon, nitrogen, phosphorus and other unutilized micronutrients that often require significant costs for disposal. However, these nutrients can be readily taken up by algae through photosynthetic activity, producing a lipid product that can be converted into advanced biofuel (i.e., biodiesel or jet fuel). By combining the cultivation of high lipid producing algae with agricultural wastewater remediation, algal-based biofuel can be produced with a net positive environmental impact, reducing anthropogenic effects on surrounding waterways and ecosystems. The purpose of this research is to provide a model for expected algal species performance in specific agricultural waste streams for use in real life applications. The primary hypothesis is that an encapsulated algal system can provide a more densely populated biomass environment for maximum nutrient uptake and allow for biomass retention and easy lipid extraction without the need for costly downstream processing equipment.


Although algae can utilize a variety of waste streams for growth, this research will focus on dairy anaerobic digester (AD) centrate. The first phase of this work will investigate several promising algal species to determine their growth rates, lipid production and nutrient removal potential for the purpose of determining a model for algal species performance. Different algal species produce a variety of cellular lipids, including triterpenes and triglycerides; therefore, lipid yield will be assessed in the context of the applicability for biofuel production. The ability of single or multispecies mixtures to sequester nutrients in this application will be evaluated alongside lipid production rates to determine which algae species or consortium of species will be selected for further research. The second phase of research involves maximizing algal biomass retention and lipid extraction through encapsulation and simultaneous in situ lipid extraction. In this phase, the study will explore different encapsulation matrices, such as calcium alginate and/or silica-based substrates as a means of retaining a biomass while allowing diffusion of essential nutrients to the cell surface.

Expected Results:

A quantitative model for algal growth, lipid production and nutrient uptake is expected to vary with each algal species based on characteristics displayed in the dairy waste stream; these are expected to be affected by turbidity, ammonia concentration and many other variables. The results will provide a quantitative model that may be used for future applications with predicted results. These parameters also will be used as inputs to a life cycle analysis model to evaluate the economic and greenhouse gas mitigation benefits of a secondary algae-based treatment system for agricultural waste from dairy farms.

Potential to Further Environmental / Human Health Protection

Disposal of dairy waste is an environmental and financial strain for most dairy farms. This research is expected to showcase a feasible and environmentally positive biofuel and waste treatment model with expected beneficial economic implications for dairy farm operators. Reduction of dairy waste discharge can result in significant reduction of adjacent and downstream waterway eutrophication, resulting in an improved environmental impact.

Supplemental Keywords:

biofuel, algae, dairy waste

Progress and Final Reports:

  • 2012
  • Final