Groundwater basins and aquifers in the Central Valley are experiencing rising nitrate and phosphate concentrations due to anthropogenic and agricultural activity. This presents a health hazard and imposes increasing water treatment costs. High levels of nitrate exposure pose serious health risk of methemoglobinemia in infants and colon cancer in some adults. We sought to use surface agricultural waste water as a medium in which to induce algal blooms to consume nitrates and phosphates, diminishing the remaining nutrient content of the water. Algal growth in wastewater reduces nutrient loading to surface and subsurface groundwater aquifers, and presents a mode of biofuel production via algal lipid storage of excess nitrogen and phosphorus for future extraction. Four different algal strains (Chlorella sorokiniana, Chlorella vulgaris, Neochloris oleoabundans, and Scenedesmus dimorphus) were grown in pure culture batch incubations to probe their potential to modulate lipid content with agricultural wastewater as a medium. Cultures reduced nitrate and phosphate concentrations in the medium by &gt;90% and &gt;60%, respectively. Observations of lipid content with boron-dipyrromethene (BODIPY) dye showed increases in cell lipid content, increasing potential for biofuel extraction. Future steps will involve the extraction of the lipid from the harvested algal mass and subjecting it to FAME (Fatty acid methyl ester) analysis to quantify oil content. In addition, flow cytometric analysis with BODIPY will statistically assess cell size against lipid storage capacity via staining over the course of the incubations. Our results from this work will inform current mitigation strategies for wastewater treatment, reuse, and mechanisms to reduce nutrient contamination and infiltration in natural aquifers alongside the use of algae as an alternate energy source.

Sustainable wastewater treatment via algal lipid accumulation

2019 Fall National Meeting

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