Don’t Run-Off – De-oiled, Solvent-free Algae as a Sustainable Biofertilizer

1. R. Connelly, R. Pearsall, M. Montoya, B. Morrison, K. Kaden, K. Murphy, L. Eisenberg, M. Werst, R. Hebner University of Texas at Austin, Center for Electromechanics, Austin, TX OpenAlgae LLC, Austin, TX Oil Recovery Concentration Lysing Source open or closed Harvesting pH floccualtion Lysing electric field Oil Separations membrane Clean Biomass dried Significance of the Study Methods Results Processed Algae Biomass Nutritional Analysis Today, the Haber–Bosch synthetic fertilizer process consumes more than one percent of the energy on Earth and is responsible for feeding roughly one-third of the world’s population. Over time, however, aggressive fertilizer practices have become unsustainable and have led to a number of environmental problems and ironically, diminished crop yields. The use of algae as a sustainable biofertilizer is particularly appealing for many reasons. Large scale growth of algae is accelerating and the University of Texas/OpenAlgae has developed cost-effective technologies to recover algal oils for independent sale, then use the de-oiled, solvent-free biomass as a clean and sustainable biofertilizer. UT conducted a pilot study to evaluate the effects of processed de-oiled algae on the promotion of plant growth and yield. The results showed that the heights and yield of the biomass-conditioned plants were consistent with, or improved, over plants conditioned with a commercial fertilizer applied at the same concentration. These data indicate that de-oiled algal biomass processed using OpenAlgae technologies can be used as an organic alternative to commercial fertilizers. Nutrient Content of Processed Algal Biomass The OpenAlgae Mobile Algae Processing (MAP) unit % N (nitrogen) P (phosphorus) K (potassium) Ca (calcium) Mg (magnesium) Na (sodium) 8.8 5.1 5.1 0.2 0.2 0.1 N:P:K ratio (9:5:5) The nutritional content of processed algae is similar to chemical fertilizers. The N:P:K ratio was determined to be (9:5:5), and also contained trace elements necessary for plant growth. Don’t Run-Off – De-oiled, Solvent-free Algae as a Sustainable Biofertilizer Comparison of AB and CF on Tomato Yield and Height 50 50 Algae Commercial Fertilizer 40 40 The algae were concentrated via a pH-driven flocculation process, then lysed via exposure to an electric field of ~9 kV/cm to liberate algal lipids. The lipids were recovered with the OpenAlgae membrane technology without direct contact with solvents. The de-oiled processed biomass was then dried to a powder consistency and analyzed for nitrogen (N), phosphorus (P), potassium (K), and protein content. 30 30 Number of Fruits Height in Inches 20 20 10 10 0 0 Yield Height Processed Algal Biofertilizer (AB) Greenhouse Study There was no significant difference between algae- and commercial fertilizer- treated plants. Comparison of AB and CF on Basil Yield and Height 60 60 Algae Commercial Fertilizer 50 50 * Hypotheses 40 40 Weight in Grams Height in Inches 30 30 Using OpenAlgae clean processing technologies, de-oiled, solvent-free algal biomass can serve as a sustainable biofertilizer. Plants conditioned with algal biofertilizer (AB) will produce yields comparable to plants conditioned with a commercially available chemical fertilizer. 20 20 10 10 0 0 Yield Height There was no significant difference between algae- and commercial fertilizer- treated plants on plant height, but algae caused significantly more yield (*p < 0.05). Experimental Approach Comparison of AB and CF on Lettuce Yield and Height Tomatoes Basil Lettuce 350 350 Methods Algae Commercial Fertilizer 300 300 250 250 Freshwater algae , including Chlorella sp. and Scenedesmus sp. were processed using the OpenAlgae Mobile Algae Processing (MAP) unit (Figure 1), then dried to a powder. The dried algae were analyzed for N:P:K and other for nutrient content by Texas A & M AgriLife Services. The analyzed dried algae (9:5:5) was applied as a biofertilizer (12.5 kg/acre) to potted vegetables and herbs. The heights and yields of the algal biomass-conditioned plants were monitored and compared to plants conditioned with a commercial fertilizer applied at the same concentration. Weight in Grams Height in Inches 30 30 20 20 10 10 Commercial Fertilizer Processed Algal Biomass Commercial Fertilizer Processed Algal Biomass Commercial Fertilizer Processed Algal Biomass 0 0 Yield Height There was no significant difference between algae- and commercial fertilizer- treated plants The soil used in this study was a commercial topsoil with no added nutrients. In this triplicate greenhouse trial, the effect of AB on tomato, basil, and leaf lettuce growth and yield compared to controls supplemented with the same amount of commercial fertilizer. Plant height and yields (fruits or leaf production) were recorded over the course of 8 weeks. At the conclusion of the study, the bare root plants were weighed. Conclusions The heights and yields promoted by algae were comparable to, or exceeded, those produced by the commercial chemical fertilizer. De-oiled, solvent-free algal biomass can be utilized as a biofertilizer. THE UNIVERSITY OF TEXAS AT AUSTIN