SBIR Phase I: A Novel Photobiological Water Treatment Process for More Efficient Water Recovery in Advanced Water Reclamation and Brackish Groundwater Desalination Facilities

The broader impact/commercial potential of this Small Business Innovation Research Phase I project is the potential to impact water scarcity in arid and semi-arid geographies within the US and beyond. The proposed photobiological water treatment process utilizes the natural power of photosynthetic microorganisms (diatoms) and sunlight without the use of hazardous chemicals or non-renewable energy to remove contaminants such as silica, calcium, iron, manganese, phosphorus and nitrogen from the concentrated waste streams (brines) from advanced water reclamation and brackish groundwater desalination facilities. Additional clean, (re)usable water can be obtained from the treated brine quite cost-effectively, while reducing the volume of brine by >50% and producing algal biomass as a marketable by-product. This technology will reduce the environmental impact and also potentially improve the efficiency of water treatment. This Phase I project will have broader impacts on the advancement of science and technology related to environmental microbiology, water reuse and water resource management. The experimental data to be generated in this project could reveal many characteristics and fundamental chemistry and biology of brackish water diatoms that have not been studied in detail, as compared with those found in the freshwater and marine environment. The technical objectives in this Phase I research project are to investigate the feasibility of a diatom-based photobiological process for scalant and nutrient removal to recover more fresh water from reverse osmosis concentrate; to characterize the byproducts of this process including organic matter and algal biomass; and to investigate the scale-up challenges. The challenges and opportunities include: (1) the optimization of the biomass growth and constituent removal, including diatom strain screening, (2) impacts of toxic elements, chlorine residuals, salinity, pH, temperature, light sources, intensity, and duration, (3) formation and characterization of byproducts, (4) removal of synthetic organic compounds, such as pharmaceuticals and personal care products, (5) photobiological reactor configuration and hydraulics, and (6) possible uses and economic values of algal biomass. Among them, the major challenges are the possible soluble organic byproduct formation and the relatively modest silica uptake rate. Bench- and pilot-scale experiments will be conducted to optimize the photobiological process to enable a full-scale application with a reasonable footprint. Careful diatom strain/species selection and more detailed chemical and biochemical analyses will also facilitate further process optimization and understanding of the fate of byproducts, their impacts on subsequent desalination, and possible control strategies.