Algae-based bioremediation of air emissions and wastewaters

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Algae can effectively remove contaminants from the environment, including carbon dioxide from power plant flue gas emissions into the atmosphere; and nitrogen and phosphorus from contaminated ground, waste and surface waters.

An example of the bioremediation research projects done in the LARB includes exploring the feasibility of removing nitrate (NO3-) from agriculture runoff using microalgae grown in large-scale photobioreactors. Arizona is among those states that have major problems with NO3-contamination in surface and groundwater. A large portion of this contamination is a result of agricultural activities and concentrated animal feeding operations. Over 800 wells in Arizona contain nitrate levels above the maximum contaminant level (MCL) of 10 mg L-1 of nitrogen as NO3- set by U.S. EPA. High levels of NO3- in drinking water supply sources can pose a serious health risk, especially for infants. NO3- contamination also contributes to eutrophication, an increase in chemical nutrients that can cause excessive plant growth.

Because some microalgae can efficiently take up NO3- and convert it into algal biomass through the photosynthesis and nitrogen assimilation, research has been conducted to determine the feasibility of putting algae to work to clean dairy wastewater. Factors that were explored in this research included:

  • isolation and characterization of high-performance algal species
  • the effect of phosphate on growth and nitrate removal
  • the effect of initial nitrate concentration on algal growth and nitrate uptake
  • the effect of nutrient starvation on nitrate removal
  • the effect of darkness on growth and nitrate removal
  • the algal density for effective nitrate removal

LARB's research in bioremediation has been supported by:

  • Arizona Public Service
  • Arizona Department of Environmental Quality
  • U.S. Bureau of Reclamation
  • U.S. Department of Agriculture
  • U.S. Geological Survey

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