Algae and bacteria together can treat wastewater efficiently! 

Are you looking for a method to overcome the main problems of conventional wastewater treatment systems? We are looking for a solution by studying algal cells!

Background for research

Increasing population and demand for more freshwater, urbanization, and decreasing natural water resources are the main reasons for water recycling and wastewater treatment these days.

Conventional method for wastewater treatment

Bacteria membrane bioreactors (MBRs) have been gained considerable interest as a major technology for wastewater treatment, due to their advantages in transforming wastewater to high-quality effluent, small footprint, and high sludge concentration. However, high aeration energy consumption and membrane fouling which limited its wide applicability, still are of concern.

Algae and bacteria

In recent years, algae/bacteria systems have drawn tremendous attention due to the high nutrient reduction efficiencies, biofuel production, and low-intensity aeration. In these systems, bacteria utilize the O2 that is produced by the algal photosynthesis process to remove nutrients whilst, in return, they release the CO2 to complete the cycle of photosynthesis, which provides a cheaper alternative to the aeration process. Also, simple mixers with much lower energy consumption could be replaced by mechanical aerations systems for mixing if algal cells could provide O2 that bacteria cells need. Moreover, Finnish environment institute (SYKE) provides a report annually about the risk of algae blooms for the Baltic Sea, a major part of the Archipelago Sea and in the southern part of the Gulf of Finland. Therefore, gathering algal blooms from Finland’s sea and using them for wastewater treatment, nutrient recovery could be a novel idea to solve the problems simultaneously.
However, no reports in detail of this approach are available. More studies should be done to understand the effects of adding Finnish local algae cells to C-MBR systems on treatment process, membrane fouling, biofilm characterization, microbial community dynamic variation and energy costs inside MMPBR systems. Moreover, the effects of using algal cells in reducing atmospheric CO2 due to photosynthesis cycle could be studied.

Aims and outcomes of the project:
1. Improvement of the performance of the membrane-based biological reactors for wastewater treatment and nutrients recovery (Done by now!)
2. Finding suitable inoculation ratio for algae and bacteria in the microalgae membrane photo bioreactors (Done by now!)
3. Reducing the energy costs of the MBR systems by replacing algal produced O2 with mechanical aeriation (Done by now!)
4. Find out which types of Finnish local algae cells are more suitable for membrane bioreactors? (I am working on this)
5. Understand how much atmospheric CO2 could be reduced by using algal cells inside the MBR systems due to photosynthesize cycle? (I will work on this)

Shahla Radmehr is a junior researcher in LUT University. She received an encouragement grant from the Foundation in 2021.