Microalgae are unicellular photosynthetic microorganisms. They fix almost 50% of global carbon emission and produce about 80% of the oxygen we breathe every day. Microalgae absorb sunlight and fix CO2 in aquatic media to convert photon energy into chemical energy. Besides light and CO2, microalgae need nutrients for growth, such as nitrogen and phosphorus. Both these nutrients are available in excess in drain water.
Fig. Microscopic Pictures of different microalgae species
Microalgae technology is ideal for wastewater treatment in warm temperate climates were warmth and light are in abundance. Algae technology results in higher nutrients assimilation efficiencies than other technologies. Additionally, microalgae photobioreactors are also efficient at removing persistent pharmaceuticals, such as diclofenac and carbamazepine, human pathogens and heavy metals.
To make this technology possible research is needed. The current bottlenecks for using microalgae technology for water treatment are the technology’s footprint, the light intensity needs and the energy intensive separation step of biomass and treated liquid. In this project, the research will focus on these aspects.
We will compare the PBRs performance efficiency of suspended microalgae versus self-sedimenting algal-bacterial community. We will research how native species perform in relation to lab species in terms of nutrient recovery and pollutants removal. By using natural occurring microalgae species and a more oxidizing growing environment in the closed PBR we expect to enhance the degradation of persistent pollutants. We will also evaluate the level of contamination of the algae biomass and its limitations for field application.
Initial algae treatment systems will be able to handle up to 100 litres per day. This initial design will serve as a test case for a 1000 litres per day pilot photo bioreactor system that is efficient in removing nutrients and pollutants while making biomass harvesting affordable.